TI1 LM15851 Ultra-wideband rf sampling subsystem Datasheet

Sample &
Buy
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
LM15851 Ultra-Wideband RF Sampling Subsystem
1 Features
2 Applications
•
•
•
•
•
1
•
•
•
•
•
•
•
•
•
Excellent Noise and Linearity up to and beyond
FIN = 3 GHz
Configurable DDC
Decimation Factors from 4 to 32 (Complex
Baseband Out)
Usable Output Bandwidth of 800 MHz at
4x Decimation and 4000 MSPS
Usable Output Bandwidth of 100 MHz at
32x Decimation and 4000 MSPS
Low Pin-Count JESD204B Subclass 1 Interface
Automatically Optimized Output Lane Count
Embedded Low Latency Signal Range Indication
Low Power Consumption
Key Specifications
– Max Sampling Rate: 4000 MSPS
– Min Sampling Rate: 1000 MSPS
– DDC Output Word Size: 15-Bit Complex (30
bits total)
– IMD3: −64 dBc (FIN = 2140 MHz ± 30 MHz at
−13 dBFS)
– FPBW (–3 dB): 3.2 GHz
– Supply Voltages: 1.9 V and 1.2 V
– Power Consumption
– Decimate by 10 (4000 MSPS): 2 W
– Power Down Mode: <50 mW
Wireless Infrastructure
RF-Sampling Software Defined Radio
Wideband Microwave Backhaul
DOCSIS / Cable Infrastructure
3 Description
The LM15851 device is a wideband sampling and
digital tuning device. Texas Instruments' giga-sample
analog-to-digital converter (ADC) technology enables
a large block of frequency spectrum to be sampled
directly at RF. An integrated DDC (Digital Down
Converter) provides digital filtering and downconversion. The selected frequency block is made
available on a JESD204B serial interface. Data is
output as baseband 15-bit complex information for
ease of downstream processing. Based on the digital
down-converter (DDC) decimation and link output
rate settings, this data is output on 1 to 5 lanes of the
serial interface.
The LM15851 device is available in a 68-pin VQFN
package. The device operates over the Industrial
(–40°C ≤ TA ≤ 85°C) ambient temperature range.
Device Information(1)
PART NUMBER
LM15851
PACKAGE
BODY SIZE (NOM)
VQFN (68)
10.00 mm × 10.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Decimate by 16 — Spectral Response
ƒS = 4 GHz, FIN = 1897 MHz at –1 dBFS, ƒ(NCO_x) = 1827 MHz
0
-10
-20
Amplitude (dBFS)
-30
-40
-50
-60
-70
-80
-90
-100
0
20
40
60
80
100
120
Frequency (MHz)
C002
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
7
1
1
1
2
3
8
Absolute Maximum Ratings ...................................... 8
ESD Ratings.............................................................. 9
Recommended Operating Conditions....................... 9
Thermal Information .................................................. 9
Electrical Characteristics........................................... 9
Timing Requirements .............................................. 13
Internal Characteristics ........................................... 15
Switching Characteristics ........................................ 16
Typical Characteristics ............................................ 18
Detailed Description ............................................ 23
7.1
7.2
7.3
7.4
7.5
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
23
23
24
42
45
7.6 Register Map........................................................... 47
8
Application and Implementation ........................ 72
8.1
8.2
8.3
8.4
9
Application Information............................................
Typical Application .................................................
Initialization Set-Up .................................................
Dos and Don'ts........................................................
72
72
74
74
Power Supply Recommendations...................... 75
9.1 Supply Voltage ........................................................ 75
10 Layout................................................................... 76
10.1 Layout Guidelines ................................................. 76
10.2 Layout Example .................................................... 76
10.3 Thermal Management ........................................... 79
11 Device and Documentation Support ................. 79
11.1
11.2
11.3
11.4
11.5
11.6
Device Support......................................................
Documentation Support ........................................
Community Resource............................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
79
81
81
81
81
81
12 Mechanical, Packaging, and Orderable
Information ........................................................... 81
4 Revision History
Changes from Revision C (September 2014) to Revision D
Page
•
Deleted references to time stamp including pin names (TMST+, TMST–). .......................................................................... 6
•
Added additional voltage difference parameters to the Absolute Maximum Ratings table .................................................... 8
•
Added junction temperature to the Absolute Maximum Ratings table ................................................................................... 8
•
Added common mode voltage parameter to the Recommended Operating Conditions table. Changed CLK to
SYSREF, and ~SYNC ........................................................................................................................................................... 9
•
Deleted the Differential Analog Input Connection image in The Analog Inputs section ...................................................... 24
•
Added note about offset adjust in Background Calibration Mode to the Offset Adjust section and I/O offset register
tables .................................................................................................................................................................................... 28
•
Added the Calibration Cycle Timing for Different Calibration Modes and Options table in the Timing Calibration
Mode section ........................................................................................................................................................................ 43
•
Changed 0x004-0x005 to RESERVED in the Standard SPI-3.0 Registers summary table................................................. 50
•
Changed the name of bit 0 in the Clock Generator Control 0 Register from DC_LVPECL_TS_EN to
DC_LVPECL_SYNC_en ...................................................................................................................................................... 55
Changes from Revision B (February 2014) to Revision C
•
2
Page
Changed the device status from Product Preview to Production Data .................................................................................. 1
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
5 Pin Configuration and Functions
VBG
DNC
RSV
VA12
Tdiode+
Tdiode±
VA19
RSV2
VA19
SCSb
SCLK
SDI
SDO
VD12
NCO_2b
NCO_2a
VD12
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
NKE Package
68-Pin VQFN With Thermal Pad
Top View
RBIAS+
1
51
NCO_1b
RBIAS±
2
50
NCO_1a
VCMO
3
49
VD12
VA12
17
35
DS1±
34
DS1+
33
VD12
36
VD12
37
16
DS0+
15
DEVCLK±
32
DEVCLK+
31
DS2±
DS0±
38
VD12
14
30
DS2+
VA12
29
39
SYNC~
13
VNEG_OUT
VD12
VA19
28
40
27
12
VA19
DS3±
VNEG
VD12
DS3+
41
26
42
11
25
10
VA12
OR_T1
VA19
OR_T0
VD12
24
DS4±
43
VA19
44
9
23
8
VIN±
22
VIN+
SYNC~±
DS4+
SYNC~+
VD12
45
21
46
7
VA12
6
VA19
20
VA12
SYSREF±
NCO_0a
19
NCO_0b
47
18
48
5
VA12
4
SYSREF+
VA19
VNEG
DNC = Make no external connection
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
3
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Pin Functions
PIN
NAME
EQUIVALENT CIRCUIT
NO.
TYPE
DESCRIPTION
ANALOG
RBIAS+
VA19
1
VBIAS
RBIAS–
2
TDIODE–
63
I/O
External Bias Resistor Connections
External bias resistor terminals. A 3.3 kΩ (±0.1%) resistor should be connected
between RBIAS+ and RBIAS–. The RBIAS resistor is used as a reference for
internal circuits which affect the linearity of the converter. The value and precision
of this resistor should not be compromised. These pins must be isolated from all
other signals and grounds.
Passive
Temperature Diode
These pins are the positive (anode) and negative (cathode) diode connections for
die temperature measurements. Leave these pins unconnected if they are not
used. See the Built-In Temperature Monitor Diode section for more details.
O
Bandgap Output Voltage
This pin is capable of sourcing or sinking 100 μA and can drive a load up to 80 pF.
Leave this pin unconnected if it is not used in the application. See the The
Reference Voltage section for more details.
O
Common Mode Voltage
The voltage output at this pin must be the common-mode input voltage at the VIN+
and VIN– pins when DC coupling is used. This pin is capable of sourcing or sinking
100 μA and can drive a load up to 80 pF. Leave this pin unconnected if it is not
used in the application.
I
Signal Input
The differential full-scale input range is determined by the full-scale voltage adjust
register. An internal peaking inductor (LPEAK) of 5 nH is included for parasitic
compensation.
GND
TDIODE+
64
VBG
68
Tdiode+
Tdiode±
VA19
VCM
VCMO
3
VIN+
8
GND
VA19
VIN+
To T&H+
LPEAK
GND
50 Ÿ
20 kŸ
VCM
VIN–
9
50 Ÿ
VA19
LPEAK
VIN±
To T&H±
GND
4
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Pin Functions (continued)
PIN
NAME
NO.
EQUIVALENT CIRCUIT
TYPE
DESCRIPTION
DATA
DS0−
32
DS0+
33
DS1–
35
DS1+
36
DS2–
38
DS2+
39
DS3–
41
DS3+
42
DS4–
44
DS4+
45
VD12
VA19
+
50
50
O
Data
CML These pins are the high-speed serialized-data outputs with user-configurable
pre-emphasis. These outputs must always be terminated with a 100-Ω differential
resistor at the receiver.
—
Do Not Connect
Do not connect DNC to any circuitry, power, or ground signals.
±
GND
GROUND, RESERVED, DNC
DNC
67
VA19
RSV
66
—
Reserved
Connect to Ground or Leave Unconnected: This reserved pin is a logic input for
possible future device versions. It is recommended to connect this pin to ground.
Floating this pin is also permissible.
RSV2
61
—
Reserved
Connect to Ground Connect this reserved input pin to ground for proper operation.
—
Ground (GND)
The exposed pad on the bottom of the package is the ground return for all supplies.
This pad must be connected with multiple vias to the printed circuit board (PCB)
ground planes to ensure proper electrical and thermal performance.
The exposed center pad on the bottom of the package must be thermally and
electrically connected (soldered) to a ground plane to ensure rated performance.
I
NCO ConfigSelect
These three pin pairs allow the host device to select the specific NCO frequency or
phase accumulator that is active. Each pair must be connected together and driven
with a common 1.8-V LVCMOS signal. Connect these inputs to GND if they are not
used in the application.
O
Over-Range
Over-range detection status for T0 and T1 thresholds. Leave these pins
unconnected if they are not used in the application.
GND
Thermal Pad
LVCMOS
NCO_0
47,
48
NCO_1
50,
51
VA19
50
50
NCO_2
53,
54
GND
OR_T0
25
OR_T1
26
VA19
GND
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
5
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Pin Functions (continued)
PIN
NAME
NO.
SCLK
58
EQUIVALENT CIRCUIT
TYPE
I
Serial Interface Clock
This pin functions as the serial-interface clock input which clocks the serial data in
and out. The Using the Serial Interface section describes the serial interface in
more detail.
I
Serial Data In
This pin functions as the serial-interface data input. The Using the Serial Interface
section describes the serial interface in more detail.
I
SYNC~
This pin provides the JESD204B-required synchronizing request input. A logic-low
applied to this input initiates a lane alignment sequence. The choice of LVCMOS or
differential SYNC~ is selected through bit 6 of the configuration register 0x202h.
Connect this input to GND or VA19 if differential SYNC~ input is used.
I
Serial Chip Select (active low)
This pin functions as the serial-interface chip select. The Using the Serial Interface
section describes the serial interface in more detail.
O
Serial Data Out
This pin functions as the serial-interface data output. The Using the Serial Interface
section describes the serial interface in more detail.
I
Device Clock Input
The differential device clock signal must be AC coupled to these pins. The input
signal is sampled on the rising edge of CLK.
I
SYSREF
The differential periodic waveform on these pins synchronizes the device per
JESD204B. If JESD204B subclass 1 synchronization is not required and these
inputs are not utilized they may be left unconnected. In that case ensure
SysRef_Rcvr_En=0 and SysRef_Pr_En=0.
I
SYNC~
This differential input provides the JESD204B-required synchronizing request input.
A differential logic-low applied to these inputs initiates a lane alignment sequence.
For differential SYNC~ usage, leave unconnected if SYNC_DIFFSEL = 0.
These inputs may be left unconnected if they are not used for the SYNC~function.
VA19
SDI
57
SYNC~
30
SCS
59
DESCRIPTION
GND
VA19
SDO
56
GND
DIFFERENTIAL INPUT
DEVCLK+
15
DEVCLK–
16
SYSREF+
19
SYSREF–
20
SYNC~+
22
SYNC~-
23
VA19
AGND
50
1k
V(CM_CLK)
VA19
50
AGND
6
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Pin Functions (continued)
PIN
NAME
NO.
EQUIVALENT CIRCUIT
TYPE
DESCRIPTION
—
Analog 1.2 V power supply pins
Bypass these pins to ground using one 10-µF capacitor and two 1-µF capacitors for
bulk decoupling plus one 0.1-µF capacitor per pin for individual decoupling.
—
Analog 1.9 V power supply pins
Bypass these pins to ground using one 10-µF capacitor and two 1-µF capacitors for
bulk decoupling plus one 0.1-µF capacitor per pin for individual decoupling.
—
Digital 1.2 V power supply pins
Bypass these pins to ground using one 10-µF capacitor and two 1-µF capacitors for
bulk decoupling plus one 0.1-µF capacitor per pin for individual decoupling.
I
VNEG
These pins must be decoupled to ground with a 0.1-µF ceramic capacitor near
each pin. These power input pins must be connected to the VNEG_OUT pin with a
low resistance path. The connections must be isolated from any noisy digital
signals and must also be isolated from the analog input and clock input pins.
O
VNEG_OUT
The voltage on this output can range from –1V to +1V. This pin must be decoupled
to ground with a 4.7-µF, low ESL, low ESR multi-layer ceramic chip capacitor and
connected to the VNEG input pins. This voltage must be isolated from any noisy
digital signals, clocks, and the analog input.
POWER
6
11
14
VA12
17
18
21
65
4
7
10
VA19
13
24
27
60
62
28
31
34
37
VD12
40
43
46
49
52
55
5
VNEG
VNEG_OUT
12
29
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
7
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
The soldering process must comply with TI's Reflow Temperature Profile specifications. Refer to www.ti.com/packaging. (1) (2) (3)
MIN
Supply voltage
Voltage
1.2-V supply
VA12, VD12
1.9-V supply
VA19
RF input power, PI
Junction
temperature, TJ
2.2
V
200
mV
On any input pin (except VIN+ or VIN–)
–0.15
V(VA19) +
0.15
V
0
2
V
|(VIN+) – (VIN–)| (4)
2
|(DEVCLK+) – (DEVCLK–)|
2
|(SYSREF+) – (SYSREF–)|
2
|(~SYNC+) – (~SYNC–)|
1
On VIN+, VIN–, with proper input common mode maintained. FIN ≥ 3 GHz,
Z(SOURCE) = 100 Ω, Input_Clamp_EN = 0 or 1
11.07
On VIN+, VIN–, with proper input common mode maintained. FIN = 1 GHz,
Z(SOURCE) = 100 Ω, Input_Clamp_EN = 1
14.95
On VIN+, VIN–, with proper input common mode maintained. FIN ≤ 100 MHz,
Z(SOURCE) = 100 Ω, Input_Clamp_EN = 1
20.97
(5)
VIN+ or VIN–
Power applied. Verified by High Temperature Operation Life testing to 1000
hours.
(3)
(4)
V
dBm
–25
25
mA
–50
50
mA DC
100
mA
–40
150
°C
–65
150
°C
Package (5) (sum of absolute value of all currents forced in or out, not including
power supply current)
Storage temperature, Tstg
(1)
(2)
V
–200
At any pin other than VIN+ or VIN–
Input current
UNIT
1.4
1.2-V supply difference between VA12 and VD12
On VIN+ or VIN–
Voltage difference
MAX
Reflow temperature profiles are different for lead-free and non-lead-free packages.
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
The analog inputs are protected as in the following circuit. Input-voltage magnitudes beyond the Absolute Maximum Ratings may
damage this device.
VA19
To Internal
Circuitry
I/O
GND
(5)
8
When the input voltage at any pin (other than VIN+ or VIN–) exceeds the power supply limits (that is, less than GND or greater than
VA19), the current at that pin must be limited to 25 mA. The 100-mA maximum package input current rating limits the number of pins
that can safely exceed the power supplies. This limit is not placed upon the power pins or thermal pad (GND).
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1)
±2000
Charged device model (CDM), per JEDEC specification JESD22-C101, all
pins (2)
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
All voltages are measured with respect to GND = 0 V, unless otherwise specified.
VDD
MIN
MAX
UNIT
1.14
1.26
V
1.8
2
V
1.9 supply ≥ 1.2
supply
V
V(VCMO) – 0.15
V(VCMO) + 0.15
V
0
V(VA19)
V
1.2-V supply: VA12, VD12
Supply voltage
1.9-V supply: VA19
Supply sequence (power-up and power-down)
VCMI
Analog input common mode voltage
VIN+, VIN– voltage (maintaining common mode)
DEVCLK±, SYSREF±, ~SYNC± pin voltage range
0
V(VA19)
0.4
2
SYSREF±, ~SYNC± Common Mode
0.64
1.1
V
Ambient temperature
–40
85
°C
135
°C
VID(CLK)
Differential DEVCLK±, SYSREF±, ~SYNC± amplitude
VCM(CLK)
TA
TJ
Junction temperature
V
VPP
6.4 Thermal Information
LM15851
THERMAL METRIC (1)
NKE (VQFN)
UNIT
68 PINS
RθJA
Thermal resistance, junction-to-ambient
19.8
°C/W
RθJCbot
Thermal resistance, junction-to-case (bottom)
2.7
°C/W
ψJB
Characterization parameter, junction-to-board
9.1
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
6.5 Electrical Characteristics
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN full scale range at default
setting (725 mVPP), VIN = –1 dBFS, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty
cycle, R(RBIAS) = 3.3 kΩ ±0.1%, after a foreground (FG) mode calibration with timing calibration enabled. Typical values are at
TA = 25°C. (1) (2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DYNAMIC PERFORMANCE CHARACTERISTICS
Third-order intermodulation
distortion
IMD3
F1 = 2110 MHz at −13 dBFS
F2 = 2170 MHz at −13 dBFS
–64
dBc
DECIMATE-BY-4 MODE
TA = 25°C
SNR1
Signal-to-noise ratio,
integrated across DDC alias
protected output bandwidth
Input frequency-dependent
interleaving spurs included
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
(2)
56.2
TA = 25°C, calibration = BG
59.2
TA = TMIN to TMAX, calibration = BG
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode
(1)
59.9
TA = TMIN to TMAX
dBFS
53.3
56.4
To ensure accuracy, the VA19, VA12, and VD12 pins are required to be well bypassed. Each supply pin must be decoupled with one or
more bypass capacitors.
Interleave related fixed frequency spurs at ƒS / 4 and ƒS / 2 are excluded from all SNR, SINAD, ENOB and SFDR specifications. The
magnitude of these spurs is provided separately.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
9
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Electrical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN full scale range at default
setting (725 mVPP), VIN = –1 dBFS, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty
cycle, R(RBIAS) = 3.3 kΩ ±0.1%, after a foreground (FG) mode calibration with timing calibration enabled. Typical values are at
TA = 25°C.(1)(2)
PARAMETER
TEST CONDITIONS
MIN
TA = 25°C (3)
SNR2
Signal-to-noise ratio,
integrated across DDC alias
protected output bandwidth
Input frequency-dependent
interleaving spurs excluded
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
SINAD1
TA = TMIN to TMAX (3)
(3)
60.2
57
TA = 25°C
59.9
TA = TMIN to TMAX
55.9
TA = 25°C, calibration = BG
59.2
TA = TMIN to TMAX, calibration = BG
SINAD2
56.4
60.1
TA = TMIN to TMAX (3)
56.3
TA = 25°C, calibration = BG
(3)
TA = TMIN to TMAX, calibration = BG (3)
60.1
57
TA = 25°C
Effective number of bits,
integrated across DDC alias
protected output bandwidth
Interleaving spurs included
FIN = 600 MHz, –1 dBFS, Decimate-by-4
mode
9.7
TA = TMIN to TMAX
9.0
TA = 25°C, calibration = BG
9.5
TA = TMIN to TMAX, calibration = BG
9.1
TA = 25°C (3)
ENOB2
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
9.7
TA = TMIN to TMAX (3)
9.0
TA = 25°C, calibration = BG
(3)
TA = TMIN to TMAX, calibration = BG (3)
9.7
8.5
TA = 25°C
Spurious-free dynamic range
across entire Nyquist
bandwidth
Interleaving spurs included
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
70.1
TA = TMIN to TMAX
59.2
TA = 25°C, calibration = BG
62.9
TA = TMIN to TMAX, calibration = BG
66.4
TA = 25°C (3)
SFDR2
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
71.6
TA = TMIN to TMAX (3)
60
TA = 25°C, calibration = BG
(3)
TA = TMIN to TMAX, calibration = BG (3)
FIN = 2400 MHz, –1 dBFS, Decimate-by-4 mode (3)
ƒS/2
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
74.8
–72
TA = TMIN to TMAX
–56
dBFS
TA = 25°C, calibration = BG
–65
TA = TMIN to TMAX, calibration = BG
TA = 25°C
Interleaving offset spur at ¼
sampling rate (4)
ƒS/4
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
–50.5
–68
TA = TMIN to TMAX
–55
dBFS
TA = 25°C, calibration = BG
–62
TA = TMIN to TMAX, calibration = BG
TA = 25°C
ƒS/2 – FIN
Interleaving spur at ½
sampling rate – input
frequency (4)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
(4)
10
–47.4
–75
TA = TMIN to TMAX
–62.3
dBFS
TA = 25°C, calibration = BG
TA = TMIN to TMAX, calibration = BG
(3)
dBFS
62.9
80.4
TA = 25°C
Interleaving offset spur at ½
sampling rate (4)
dBFS
51.8
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode
Spurious-free dynamic range
across entire Nyquist
bandwidth
Interleaving spurs excluded
Bits
9.1
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode (3)
SFDR1
Bits
8.5
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode
Effective number of bits,
integrated across DDC alias
protected output bandwidth
Interleaving spurs excluded
dBFS
56.4
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode (3)
ENOB1
dBFS
53.1
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
dBFS
56.7
TA = 25°C (3)
Signal-to-noise and distortion
ratio, integrated across DDC
alias protected output
bandwidth
Interleaving spurs excluded
UNIT
56.7
TA = 25°C, calibration = BG
TA = TMIN to TMAX, calibration = BG (3)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
MAX
60.1
FIN = 2400 MHz, –1 dBFS, decimate-by-4 mode (3)
Signal-to-noise and distortion
ratio, integrated across DDC
alias protected output
bandwidth
Input frequency-dependent
interleaving spurs included
TYP
–70
–51.5
Interleave related spurs at ƒS / 2 – FIN, ƒS / 4 + FIN and ƒS / 4 – FIN are excluded from these performance calculations. The magnitude
of these spurs is provided separately.
Magnitude of reported tones in output spectrum of ADC core. This tone will only be present in the DDC output for specific Decimation
and NCO settings. Careful frequency planning can be used to intentionally place unwanted tones outside the DDC output spectrum.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Electrical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN full scale range at default
setting (725 mVPP), VIN = –1 dBFS, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty
cycle, R(RBIAS) = 3.3 kΩ ±0.1%, after a foreground (FG) mode calibration with timing calibration enabled. Typical values are at
TA = 25°C.(1)(2)
PARAMETER
TEST CONDITIONS
MIN
TA = 25°C
ƒS/4 + FIN
Interleaving spur at ¼
sampling rate + input
frequency (4)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
TYP
TA = TMIN to TMAX
dBFS
–65
TA = 25°C
Interleaving spur at ¼
sampling rate – input
frequency (4)
FIN = 600 MHz, –1 dBFS, Decimate-by-4
mode
–52.8
–78
TA = TMIN to TMAX
–60.4
dBFS
TA = 25°C, calibration = BG
–65
TA = TMIN to TMAX, calibration = BG
TA = 25°C
THD
Total harmonic distortion (4)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
–52.3
–70
TA = TMIN to TMAX
–59.5
dBFS
TA = 25°C, calibration = BG
–73
TA = TMIN to TMAX, calibration = BG
TA = 25°C
HD2
Second harmonic distortion (4)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
–60
–83
TA = TMIN to TMAX
–62
dBFS
TA = 25°C, calibration = BG
–78
TA = TMIN to TMAX, calibration = BG
TA = 25°C
HD3
Third harmonic distortion (4)
FIN = 600 MHz, –1 dBFS, decimate-by-4
mode
UNIT
–58.9
TA = 25°C, calibration = BG
TA = TMIN to TMAX, calibration = BG
ƒS/4 – FIN
MAX
–73
–62.5
–72
TA = TMIN to TMAX
–59.5
dBFS
TA = 25°C, calibration = BG
–82
TA = TMIN to TMAX, calibration = BG
–62
DECIMATE-BY-8 MODE
SNR1
SNR2
SINAD1
SINAD2
ENOB1
Signal-to-noise ratio,
integrated across DDC output
bandwidth
Interleaving spurs included
Signal-to-noise ratio,
integrated across DDC output
bandwidth
Interleaving spurs excluded
Signal-to-noise and distortion
ratio, integrated across DDC
output bandwidth
Interleaving spurs included
Signal-to-noise and distortion
ratio, integrated across DDC
output bandwidth
Interleaving spurs excluded
Effective number of bits,
integrated across DDC output
bandwidth
Interleaving spurs included
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
63
Calibration = BG
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
63.3
Calibration = BG
63.3
FIN = 600 MHz, –1 dBFS, Decimate-by-8
mode
Calibration = BG
61.6
dBFS
63
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
Calibration = BG
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
dBFS
63.3
10.2
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
Calibration = BG
Spurious-free dynamic range
Interleaving Spurs Included
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
Spurious-free dynamic range
Interleaving spurs excluded
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode(5)
Calibration = BG
ƒS/2
Interleaving offset spur at ½
sampling rate (4)
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
ƒS/4
Interleaving offset spur at ¼
sampling rate (4)
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
ƒS/2 – FIN
Interleaving spur at ½
sampling rate – input
frequency (4)
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
ƒS/4 + FIN
Interleaving spur at ¼
sampling rate + input
frequency (4)
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
SFDR2
dBFS
54.6
63.3
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode (3)
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode(5)
SFDR1
dBFS
54.6
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode (3)
Effective number of bits,
integrated across DDC output
bandwidth
Interleaving spurs excluded
ENOB2
61.6
10.0
Bits
8.8
10.2
Bits
10.2
74.9
dBFS
68.3
77.8
dBFS
77.8
–73
dBFS
–72
–70
dBFS
–66
–76
dBFS
–67
–72
dBFS
–64
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
11
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Electrical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN full scale range at default
setting (725 mVPP), VIN = –1 dBFS, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty
cycle, R(RBIAS) = 3.3 kΩ ±0.1%, after a foreground (FG) mode calibration with timing calibration enabled. Typical values are at
TA = 25°C.(1)(2)
PARAMETER
TEST CONDITIONS
ƒS/4 – FIN
Interleaving spur at ¼
sampling rate – input
frequency (4)
THD
Total harmonic distortion(6)
HD2
Second harmonic distortion(6)
HD3
Third harmonic distortion(6)
MIN
TYP
MAX
UNIT
–74
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
Calibration = BG
dBFS
–67
–70
–72
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
–71
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
–80
Calibration = BG
dBFS
–79
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
–78
FIN = 600 MHz, –1 dBFS, decimate-by-8
mode
–74
Calibration = BG
dBFS
–80
FIN = 2400 MHz, –1 dBFS, decimate-by-8 mode
dBFS
–-77
DDC CHARACTERISTICS
Alias protection (5)
Alias protected bandwidth
SFDR-DDC
(5)
Spurious-free dynamic range
of digital down-converter (5)
Implementation loss
80
dB
80
% of
output BW
100
dB
(5)
0.5
dB
800
mVPP
ANALOG INPUT CHARACTERISTICS
Minimum FSR setting (6)
Full-scale analog-differential
input range
VID(VIN)
CI(VIN)
Analog input capacitance (5)
RID(VIN)
Differential input resistance
500
Default FSR setting, TA = TMIN to TMAX
650
950
Differential
0.05
Each input pin to ground
FPBW
725
Maximum FSR setting (6)
pF
1.5
80
95
–3 dB — calibration = BG
2.8
–3 dB — calibration = FG
3.2
DC to 2 GHz
1.2
2 GHz to 4 GHz
3.8
DC to 2 GHz — calibration = BG
1.5
2 GHz to 4 GHz — calibration = BG
4.5
pF
110
Full power bandwidth
Ω
GHz
Gain flatness
dB
ANALOG OUTPUT CHARACTERISTICS (VCMO, VBG)
I(VCMO) = ±100 µA, TA = 25°C
V(VCMO)
Common-mode output
voltage
TCVO(VCMO)
Common-mode outputvoltage temperature
coefficient
C(LOAD_VCMO)
Maximum VCMO output load
capacitance
VO(BG)
Bandgap reference output
voltage
I(BG) = ±100 µA, TA = 25°C
TCVref(BG)
Bandgap reference voltage
temperature coefficient
TA = TMIN to TMAX,
I(BG) = ±100 µA
C(LOAD_BG)
Maximum bandgap reference
output load capacitance
1.225
V
I(VCMO) = ±100 µA, TA = TMIN to TMAX
1.185
TA = TMIN to TMAX
1.265
-21
ppm/°C
80
pF
1.248
V
I(BG) = ±100 µA, TA = TMIN to TMAX
1.195
1.3
0
ppm/°C
80
pF
TEMPERATURE DIODE CHARACTERISTICS
V(TDIODE)
(5)
(6)
12
Temperature diode voltage
slope
Offset voltage (approx. 0.77 V) varies with
process and must be measured for each
part. Offset measurement should be done
with PowerDown=1 to minimize device selfheating.
100-µA forward current
Device active
–1.6
mV/°C
100-µA forward current
Device in power-down
–1.6
mV/°C
This parameter is specified by design and is not tested in production.
This parameter is specified by design, characterization, or both and is not tested in production.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Electrical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN full scale range at default
setting (725 mVPP), VIN = –1 dBFS, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty
cycle, R(RBIAS) = 3.3 kΩ ±0.1%, after a foreground (FG) mode calibration with timing calibration enabled. Typical values are at
TA = 25°C.(1)(2)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Sine wave clock, TA = TMIN to TMAX
0.4
0.6
2
VPP
Square wave clock, TA = TMIN to TMAX
0.4
0.6
2
VPP
CLOCK INPUT CHARACTERISTICS (DEVCLK±, SYSREF±, SYNC~)
VID(CLK)
Differential clock input level
II(CLK)
Input current
CI(CLK)
RID(CLK)
Input capacitance (5)
VI = 0 or VI = VA
Differential
±1
µA
0.02
pF
1
pF
Each input to ground
Differential input resistance
TA = 25°C
Ω
95
TA = TMIN to TMAX
80
110
Ω
330
mV peak
CML OUTPUT CHARACTERISTICS (DS0–DS7±)
VOD
Differential output voltage
VO(ofs)
Output offset voltage
IOS
Output short-circuit current
ZOD
Differential output impedance
Assumes ideal 100-Ω load
Measured differentially
Default pre-emphasis setting
280
305
0.6
Output+ and output– shorted together
±6
Output+ or output– shorted to 0 V
12
V
mA
Ω
100
LVCMOS INPUT CHARACTERISTICS (SDI, SCLK, SCS, SYNC~)
VIH
Logic high input voltage
See
(6)
VIL
Logic low input voltage
See
(6)
CI
Input capacitance (5) (7)
Each input to ground
0.83
V
0.4
V
1
pF
LVCMOS OUTPUT CHARACTERISTICS (SDO, OR_T0, OR_T1)
VOH
CMOS H level output
IOH = –400 µA (6)
VOL
CMOS L level output
IOH = 400 µA (6)
0.01
0.15
V
1.65
1.9
V
POWER SUPPLY CHARACTERISTICS
I(VA19)
Analog 1.9-V supply current
PD = 0, calibration = BG, decimate by 8, DDR = 0, P54 = 1
560
607
mA
I(VA12)
Analog 1.2-V supply current
PD = 0, calibration = BG, decimate by 8, DDR = 0, P54 = 1
377
428
mA
I(VD12)
Digital 1.2-V supply current
PD = 0, calibration = BG, decimate by 8, DDR = 0, P54 = 1
541
826
mA
PD = 0, calibration = BG, decimate by 8, DDR = 0, P54 = 1
2.17
2.66
PD = 1
< 50
PC
(7)
W
Power consumption
mW
The digital control pin capacitances are die capacitances only and is in addition to package and bond-wire capacitance of approximately
0.4 pF.
6.6 Timing Requirements
MIN
NOM
MAX
UNIT
4
GHz
DEVICE (SAMPLING) CLOCK
ƒ(DEVCLK)
Input DEVCLK frequency
Sampling rate is equal to clock input
td(A)
Sampling (aperture) delay
Input CLK transition to sampling instant
t(AJ)
Aperture jitter
1
0.64
ns
0.1
ps RMS
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
13
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Timing Requirements (continued)
MIN
t(LAT_DDC)
ADC core and DDC latency (1)
NOM
Decimation = 4, DDR = 1, P54 = 0
292
Decimation = 4, DDR = 1, P54 = 1
284
Decimation = 8, DDR = 0, P54 = 0
384
Decimation = 8, DDR = 0, P54 = 1
368
Decimation = 8, DDR = 1, P54 = 0
392
Decimation = 8, DDR = 1, P54 = 1
368
Decimation = 10, DDR = 0, P54 = 0
386
Decimation = 10, DDR = 1, P54 = 0
386
Decimation = 16, DDR = 0, P54 = 0
608
Decimation = 16, DDR = 0, P54 = 1
560
Decimation = 16, DDR = 1, P54 = 0
608
Decimation = 16, DDR = 1, P54 = 1
560
Decimation = 20, DDR = 0, P54 = 0
568
Decimation = 20, DDR = 1, P54 = 0
568
Decimation = 32, DDR = 0, P54 = 0
1044
Decimation = 32, DDR = 0, P54 = 1
948
Decimation = 32, DDR = 1, P54 = 0
1044
MAX
UNIT
t(DEVCLK)
JESD204B INTERFACE LINK TIMING CHARACTERISTICS (REFER TO Figure 1)
SYSREF to LMFC delay
Functional delay between SYSREF
assertion latched and LMFC frame
boundary (1)
td(LMFC)
All decimation modes
Decimation = 4, DDR = 1, P54 = 0
52.7
Decimation = 4, DDR = 1, P54 = 1
43.9
Decimation = 8, DDR = 0, P54 = 0
60.7
Decimation = 8, DDR = 0, P54 = 1
51.5
Decimation = 8, DDR = 1, P54 = 0
52.7
Decimation = 8, DDR = 1, P54 = 1
43.9
Decimation = 10, DDR = 0, P54 = 0
60.7
LMFC to frame boundary delay - decimation
Decimation = 10, DDR = 1, P54
modes
Functional delay from LMFC frame boundary Decimation = 16, DDR = 0, P54
to beginning of next multi-frame in
Decimation = 16, DDR = 0, P54
transmitted data (2)
Decimation = 16, DDR = 1, P54
td(TX)
tsu(SYNC~F)
th(SYNC~F)
40
=0
52.7
=0
60.7
=1
51.5
=0
52.7
Decimation = 16, DDR = 1, P54 = 1
43.9
Decimation = 20, DDR = 0, P54 = 0
60.7
Decimation = 20, DDR = 1, P54 = 0
52.7
Decimation = 32, DDR = 0, P54 = 0
60.7
Decimation = 32, DDR = 0, P54 = 1
51.5
Decimation = 32, DDR = 1, P54 = 0
52.7
SYNC~ to LMFC setup time (3)
Required SYNC~ setup time relative to the internal LMFC boundary.
40
SYNC~ to LMFC hold time (3)
Required SYNC~ hold time relative to the internal LMFC boundary.
–8
t(SYNC~)
SYNC~ assertion time
Required SYNC~ assertion time before deassertion to initiate a link resynchronization.
td(LMFC)
Delay from SYSREF sampled high by DEVCLK to internal LMFC boundary
t(ILA)
(1)
(2)
(3)
14
Duration of initial lane alignment sequence
t(DEVCLK)
t(DEVCLK)
t(DEVCLK)
4
Frame clock
cycles
40
t(DEVCLK)
4
Multi-frame
clock cycles
Unless otherwise specified, delays quoted are exact un-rounded functional delays (assuming zero propagation delay).
The values given are functional delays only. Additional propagation delay of 0 to 3 clock cycles will be present.
This parameter must be met to achieve deterministic alignment of the data frame and NCO phase to other similar devices. If this
parameter is not met the device will still function correctly but will not be aligned to other devices.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Timing Requirements (continued)
MIN
NOM
MAX
UNIT
SYSREF
tsu(SYS)
Setup time SYSREF relative to DEVCLK rising edge (4)
40
th(SYS)
Hold time SYSREF relative to DEVCLK rising edge (4)
40
t(PH_SYS)
SYSREF assertion duration after rising edge event.
8
t(PL_SYS)
SYSREF deassertion duration after falling edge event.
8
t(SYS)
ps
t(DEVCLK)
t(DEVCLK)
DDR = 0, P54 = 0
K×F×
10
DDR = 0, P54 = 1
K×F×
8
DDR = 1, P54 = 0
K×F×
5
DDR = 1, P54 = 1
K×F×
4
Period SYSREF±
ps
t(DEVCLK)
SERIAL INTERFACE (REFER TO Figure 2)
ƒ(SCK)
Serial clock frequency (5)
t(PH)
Serial clock high time
20
ns
t(PL)
Serial clock low time
20
ns
tsu
Serial-data to serial-clock rising setup time (5)
10
ns
th
Serial-data to serial clock rising hold time (5)
10
ns
t(CSS)
SCS-to-serial clock rising setup time
10
ns
t(CSH)
SCS-to-serial clock falling hold time
10
ns
t(IAG)
Inter-access gap
10
ns
(4)
(5)
20
MHz
This parameter is specified by design, characterization, or both and is not tested in production.
This parameter is specified by design and is not tested in production.
6.7 Internal Characteristics
PARAMETER
TEST CONDITIONS
MIN
NOM
MAX
UNIT
DEVICE (SAMPLING) CLOCK
td(A)
Sampling (aperture) delay
t(AJ)
Aperture jitter
Input CLK transition to sampling instant
0.64
ns
0.1
ps RMS
CALIBRATION TIMING CHARACTERISTICS (REFER TO THE CALIBRATION SECTION)
t(CAL)
Calibration = FG, T_AUTO=1
227 ×
106
Calibration = FG, T_AUTO=0
102 ×
106
Calibration cycle time
t(DEVCLK)
JESD204B INTERFACE LINK TIMING CHARACTERISTICS (REFER TO Figure 1)
td(LMFC)
(1)
SYSREF to LMFC delay
Functional delay between SYSREF assertion
latched and LMFC frame boundary (1)
All decimation modes
40
t(DEVCLK)
Unless otherwise specified, delays quoted are exact un-rounded functional delays (assuming zero propagation delay).
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
15
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Internal Characteristics (continued)
PARAMETER
LMFC to frame boundary delay - decimation
modes
Functional delay from LMFC frame boundary
to beginning of next multi-frame in transmitted
data (2)
td(TX)
td(LMFC)
t(ILA)
(2)
TEST CONDITIONS
MIN
NOM
Decimation = 4, DDR = 1, P54 = 0
52.7
Decimation = 4, DDR = 1, P54 = 1
43.9
Decimation = 8, DDR = 0, P54 = 0
60.7
Decimation = 8, DDR = 0, P54 = 1
51.5
Decimation = 8, DDR = 1, P54 = 0
52.7
Decimation = 8, DDR = 1, P54 = 1
43.9
Decimation = 10, DDR = 0, P54 = 0
60.7
Decimation = 10, DDR = 1, P54 = 0
52.7
Decimation = 16, DDR = 0, P54 = 0
60.7
Decimation = 16, DDR = 0, P54 = 1
51.5
Decimation = 16, DDR = 1, P54 = 0
52.7
Decimation = 16, DDR = 1, P54 = 1
43.9
Decimation = 20, DDR = 0, P54 = 0
60.7
Decimation = 20, DDR = 1, P54 = 0
52.7
Decimation = 32, DDR = 0, P54 = 0
60.7
Decimation = 32, DDR = 0, P54 = 1
51.5
Decimation = 32, DDR = 1, P54 = 0
52.7
Delay from SYSREF sampled high by DEVCLK to internal LMFC boundary
Duration of initial lane alignment sequence
MAX
UNIT
t(DEVCLK)
40
t(DEVCLK)
4
Multi-frame
clock cycles
The values given are functional delays only. Additional propagation delay of 0 to 3 clock cycles will be present.
6.8 Switching Characteristics
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a foreground mode calibration with timing calibration enabled. Typical values are at TA = 25°C.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SERIAL DATA OUTPUTS
Serialized output bit rate
Serialized output bit rate
1
10
DDR = 0, P54 = 0
ƒS
DDR = 0, P54 = 1
1.25 ×
ƒS
DDR = 1, P54 = 0
2 × ƒS
DDR = 1, P54 = 1
2.5 ×
ƒS
Gbps
tTLH
LH transition time — differential
10% to 90%, 8 Gbps
35
ps
tTHL
HL transition time — differential
10% to 90%, 8 Gbps
35
ps
UI
Unit interval
8 Gbps serial rate
125
ps
DDJ
Data dependent jitter
8 Gbps serial rate
11.3
ps
RJ
Random Jitter
8 Gbps serial rate
1.4
ps
SERIAL INTERFACE
t(OZD)
SDO tri-state to driven
t(ODZ)
SDO driven to tri-state
t(OD)
SDO output delay
16
See Figure 2
Submit Documentation Feedback
2.5
5
ns
5
ns
20
ns
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
SYSREF assertion
SYNC~ assertion
latched
latched
SYNC~ de-assertion
latched
t(SYNC~)
tsu(SYNC~-F)
th(-SYNC~-F)
SYNC~
t(ILA)
Serial Data
XXX
th(SYS)
XXX
K28.5
K28.5
ILA
td(TX)
tsu(SYS)
ILA
Valid Data
td(TX)
DEVCLK
t(PL-SYS)
SYSREF
t(PH-SYS)
Tx Frame Clk
Tx LMFC Boundary
td(LMFC)
Code Group
Synchronization
Frame Clock
Alignment
Initial Frame and Lane
Synchronization
Data
Transmission
Figure 1. JESD204 Synchronization
st
1 clock
th
16
th
clock
24
clock
SCLK
t(CSH)
t(PH)
t(CSS)
t(CSS)
t(PL)
t(CSH)
t(IAG)
t(PH) + t(PL) = t(P) = 1 / ¦(SCK)
SCS
tsu
th
tsu
SDI
D7
D1
th
D0
Write Command
COMMAND FIELD
t(OD)
SDO
Hi-Z
D7
t(OZD)
D1
D0
Read Command
Hi-Z
t(ODZ)
Figure 2. Serial Interface Timing
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
17
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
6.9 Typical Characteristics
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a Foreground mode calibration with Timing Calibration enabled. TA = 25°C. VI = –1 dBFS.
100
100
SNR (dBFS)
SINAD (dBFS)
SFDR (dBFS)
90
Magnitude (dBFS)
Magnitude (dBFS)
90
80
70
60
50
80
70
60
50
40
40
4
8
12
16
20
Decimation Factor
24
28
32
4
8
12
D019
FIN = 608 MHz
16
20
Decimation Factor
24
28
32
D024
FIN = 2483 MHz
Figure 3. SNR, SINAD, SFDR vs Decimation Setting
Figure 4. SNR, SINAD, SFDR vs Decimation Setting
105
90
SNR (dBFS)
SINAD (dBFS)
SFDR (dBFS)
SNR (dBFS)
SINAD (dBFS)
SFDR (dBFS)
85
Magnitude (dBFS)
90
Magnitude (dBFS)
SNR (dBFS)
SINAD (dBFS)
SFDR (dBFS)
75
60
80
75
70
65
60
45
-10
-5
0
5
All Supply Voltage Variation from Nominal (%)
Decimate by 16 mode
55
-50
10
FIN = 608 MHz
75
100
D033
FIN = 608 MHz
Figure 6. SNR, SINAD, SFDR vs Temperature
11
10
10
ENOB (Bits)
11
9
9
8
8
4
8
12
16
20
Decimation Factor
24
28
32
4
8
12
D021
FIN = 608 MHz
16
20
Decimation Factor
24
28
32
D026
FIN = 2483 MHz
Figure 7. ENOB vs Decimation Setting
18
0
25
50
Ambient Temperature (°C)
Decimate by 16 mode
Figure 5. SNR, SINAD, SFDR vs Supply
ENOB (Bits)
-25
D043
Submit Documentation Feedback
Figure 8. ENOB vs Decimation Setting
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Typical Characteristics (continued)
11
11
10.5
10.5
ENOB (Bits)
ENOB (Bits)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a Foreground mode calibration with Timing Calibration enabled. TA = 25°C. VI = –1 dBFS.
10
9.5
10
9.5
9
-10
-5
0
5
All Supply Variation from Nominal (%)
Decimate by 16 mode
9
-50
10
-25
FIN = 608 MHz
Figure 9. ENOB vs Supply
75
100
D034
FIN = 608 MHz
Figure 10. ENOB vs Temperature
1.9
Power Consumption (W)
Power Consumption (W)
25
50
Temperature (°C)
Decimate by 16 mode
2
1.9
1.8
1.7
1.6
4
8
12
16
20
Decimation Factor
24
28
1.8
1.7
1.6
-50
32
0
25
50
Ambient Temperature (°C)
Decimate by 16 mode
Figure 11. Power Consumption vs Decimation Setting
75
100
D035
FIN = 608 MHz
Figure 12. Power Consumption vs Temperature
2
0.6
VA19
VA12
VD12
0.5
Supply Current (A)
1.9
1.8
1.7
1.6
1.5
-10
-25
D022
FIN = 608 MHz
Power Consumption (W)
0
D044
0.4
0.3
0.2
0.1
-5
0
5
All Supply Voltage Variation from Nominal (%)
Decimate by 16 mode
10
FIN = 608 MHz
Figure 13. Power Consumption vs Supply
4
8
12
D045
16
20
Decimation Factor
24
28
32
D023
FIN = 608 MHz
Figure 14. Supply Current vs Decimation Setting
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
19
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Typical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a Foreground mode calibration with Timing Calibration enabled. TA = 25°C. VI = –1 dBFS.
0.7
0.7
VA19
VA12
VD12
0.6
Supply Current (A)
Supply Current (A)
0.6
VA19
VA12
VD12
0.5
0.4
0.3
0.5
0.4
0.3
0.2
-10
-5
0
5
All Supply Voltage Variation from Nominal (%)
Decimate by 16 mode
0.2
-50
10
-25
D046
FIN = 608 MHz
Decimate by 16 mode
Figure 15. Supply Current vs Supply Voltage
75
100
D036
FIN = 608 MHz
Figure 16. Supply Current vs Temperature
6
6
Corrected for Setup Losses
Raw Insertion Loss
Curve Fit
3
Corrected for Setup Losses
Raw Insertion Loss
Curve Fit
3
0
Insertion Loss (dB)
Insertion Loss (dB)
0
25
50
Ambient Temperature (°C)
-3
-6
-9
0
-3
-6
-9
-12
-12
-15
-15
0
0
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Input Frequency (MHz)
D037
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Input Frequency (MHz)
D038
Foreground calibration mode
Background calibration mode
Figure 17. Insertion Loss vs Input Frequency
Figure 18. Insertion Loss vs Input Frequency
30
0.0025
Filter Response
-80dB
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-180
-0.01
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
Figure 19. Decimate by 4 - Stopband Response
20
0
D055
0.025
0.05
0.075
0.1
Normalized to Filter Input Sample Rate
0.125
D056
Figure 20. Decimate by 4 - Passband Response
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Typical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a Foreground mode calibration with Timing Calibration enabled. TA = 25°C. VI = –1 dBFS.
30
0.0025
Filter Response
-80dB
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-180
-0.01
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
0
D057
Figure 21. Decimate by 8 - Stopband Response
0.01
0.02
0.03
0.04
0.05
Normalized to Filter Input Sample Rate
0.06
D058
Figure 22. Decimate by 8 - Passband Response
30
0.0025
Filter Response
-80dB
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-180
-0.01
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
0
D059
Figure 23. Decimate by 10 - Stopband Response
0.01
0.02
0.03
0.04
Normalized to Filter Input Sample Rate
0.05
D060
Figure 24. Decimate by 10 - Passband Response
0.0025
30
Filter Response
-80dB
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-0.01
-180
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
0
D061
Figure 25. Decimate by 16 - Stopband Response
0.006
0.012
0.018
0.024
Normalized to Filter Input Sample Rate
0.03
D062
Figure 26. Decimate by 16 - Passband Response
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
21
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Typical Characteristics (continued)
Unless otherwise noted, these specifications apply for V(VA12) = V(VD12) = 1.2 V, V(VA19) = 1.9 V, VIN FSR (AC coupled) =
Default setting, differential AC-coupled sinewave input clock, ƒ(DEVCLK) = 4 GHz at 0.5 VPP with 50% duty cycle, R(RBIAS) = 3.3
kΩ ±0.1%, after a Foreground mode calibration with Timing Calibration enabled. TA = 25°C. VI = –1 dBFS.
30
0.0025
Filter Response
-80dB
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-180
-0.01
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
0
D063
Figure 27. Decimate by 20 - Stopband Response
0.005
0.01
0.015
0.02
Normalized to Filter Input Sample Rate
0.025
D064
Figure 28. Decimate by 20 - Passband Response
30
0.0025
Filter Response
0
0
Magnitude (dB)
Magnitude (dB)
-30
-60
-90
-0.0025
-0.005
-120
-0.0075
-150
-180
-0.01
0
0.1
0.2
0.3
0.4
Normalized to Filter Input Sample Rate
0.5
Figure 29. Decimate by 32 - Stopband Response
22
0
D065
0.003
0.006
0.009
0.012
Normalized to Filter Input Sample Rate
0.015
D066
Figure 30. Decimate by 32 - Passband Response
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7 Detailed Description
7.1 Overview
The LM15851 device is an ultra-wideband sampling and digital tuning subsystem. The device combines a verywideband and high sampling-rate ADC front-end with a configurable digital-down conversion block. This
combination provides the necessary features to facilitate the development of flexible software-defined radio
products for a wide range of communications applications.
The LM15851 device is based on an ultra high-speed ADC core. The core uses an interleaved calibrated folding
and interpolating architecture that results in very high sampling rate, very good dynamic performance, and
relatively low-power consumption. This ADC core is followed by a configurable DDC block which is implemented
on a small geometry CMOS. The DDC block provides a range of decimation settings that allow the product to
work in ultra-wideband, wideband, and more-narrow-band receive systems. The output data from the DDC block
is transmitted through a JESD204B-compatible multi-lane serial-output system. This system minimizes the
number of data pairs required to convey the output data to the downstream processing circuitry.
7.2 Functional Block Diagram
NCO_2
NCO_2
Buffer
VIN+
ADC
VIN±
NCO_1
NCO_1
VCM
DDC
VCMO
VBG
RBIAS+
RBIAS±
NCO_0
NCO_0
REF
DS4+
DS4±
DEVCLK±
VCM CLK
DS3+
JESD204B Interface
DEVCLK+
Clock
Sync
SYSREF+
SYSREF±
SYNC~+
DS3±
DS2+
DS2±
DS1+
DS1±
SYNC~±
DS0+
SYNC~
DS0±
OR_T0
TDIODE+
Overrange
Detection
OR_T1
TDIODE±
Configuration
Registers
SPI
Interface
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
SCS
SCLK
SDI
SDO
23
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Functional Block Diagram (continued)
Configurable 32-bit NCO
and Mixer
Configurable
Decimation Filters
Filter
15 bit I
Complex Baseband
Output
12 bit
Filter
15 bit Q
90°
Oscillator
Figure 31. DDC Details Block Diagram
7.3 Feature Description
7.3.1 Signal Acquisition
The analog input is sampled on the rising edge of CLK and the digital equivalent of that data is available in the
serialized datastream t(LAT) or t(LAT_DDC) input clock cycles later.
The LM15851 device converts as long as the input clock signal is present. The fully-differential comparator
design and the innovative design of the sample-and-hold amplifier, together with calibration, enables very good
performance at input frequencies beyond 3 GHz. The LM15851 data is output on a high-speed serial JESD204B
interface.
7.3.2 The Analog Inputs
A differential input signal must be used to drive the LM15851 device. Operation with a single-ended signal is not
recommended as performance suffers. The input signals can be either be AC coupled or DC coupled. The
analog inputs are internally connected to the VCMO bias voltage. When DC-coupled input signals are used, the
common mode voltage of the applied signal must meet the device Input common mode requirements. See VCMI
in the Recommended Operating Conditions table.
The full-scale input range for each converter can be adjusted through the serial interface. See the Full Scale
Range Adjust section.
The buffered analog inputs simplify the task of driving these inputs and the RC pole that is generally used at
sampling ADC inputs is not required. If an amplifier circuit before the ADC is desired, use care when selecting an
amplifier with adequate noise and distortion performance and adequate gain at the frequencies used for the
application. If gain is not required, a balun (balanced-to-unbalanced transformer) is generally used to provide
single ended (SE) to differential conversion.
The input impedance of VIN± consists of two 50-Ω resistors in series between the inputs and a capacitance from
each of these inputs to ground. A resistance of approximately 20 kΩ exists from the center point of the 50-Ω
resistors to the on-chip VCMO providing self-biasing for AC-coupled applications.
Performance is good in both DC-coupled mode and AC coupled mode, provided the common-mode voltage at
the analog input is within specifications.
24
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Feature Description (continued)
7.3.2.1 Input Clamp
The LM15851 maximum DC input voltage is limited to the range 0 to 2 V to prevent damage to the device. To
help maintain these limits, an active input clamping circuit is incorporated which sources or sinks input currents
up to ±50 mA. The clamping circuit is enabled by default and is controlled via the Input_Clamp_EN bit (register
0x034, bit 5). The protection provided by this circuit is limited as follows:
• Shunt current-clamping is only effective for non-zero source impedances.
• At frequencies above 3 GHz the clamping is ineffective because of the finite turn-on and turn-off time of the
switch.
With these limitations in mind, analysis has been done to determine the allowable input signal levels as a
function of input frequency when the Input Clamp is enabled, assuming the source impedance matches the input
impedance of the device (100-Ω differential). This information is incorporated in the Absolute Maximum Ratings
table.
7.3.2.2 AC Coupled Input Usage
The easiest way to accomplish SE-to-differential conversion for AC-coupled signals is with an appropriate balun.
C(couple)
50- Source
VIN+
R(VIN)
1:2 Balun
C(couple)
VIN±
Figure 32. Single-Ended-to-Differential Signal Conversion With a Balun
Figure 32 shows a generic depiction of a SE-to-differential signal conversion using a balun. The circuitry specific
to the balun depends on the type of balun selected and the overall board layout. TI recommends that the system
designer contact the manufacturer of the selected balun to aid in designing the best performing single-ended to
differential conversion circuit using that particular balun.
When selecting a balun, understanding the input architecture of the ADC is important. Specific balun parameters
must be considered. The balun must match the impedance of the analog source to the on-chip 100-Ω differential
input termination of the LM15851 device. The range of this input termination resistor is described in the Electrical
Characteristics table as the specification RID.
Also, as a result of the ADC architecture, the phase and amplitude balance are important. The lowest possible
phase and amplitude imbalance is desired when selecting a balun. The phase imbalance must be no more than
±2.5° and the amplitude imbalance must be limited to less than 1 dB at the desired input frequency range.
Finally, when selecting a balun, the voltage standing-wave ratio (VSWR), bandwidth, and insertion loss of the
balun must also be considered. The VSWR aids in determining the overall transmission line termination
capability of the balun when interfacing to the ADC input. The insertion loss must be considered so that the
signal at the balun output is within the specified input range of the ADC as described in the Electrical
Characteristics table as the specification VID.
Table 1 lists the recommended baluns for specific signal frequency ranges.
Table 1. Balun Recommendations
MINIMUM
FREQUENCY (MHz)
MAXIMUM
FREQUENCY (MHz)
IMPEDANCE RATIO
PART NUMBER
MANUFACTURER
Mini-Circuits
4.5
3000
1:1
TC1-1-13MA+
400
3000
1:2
B0430J50100AHF
Anaren
30
1800
1:2
ADTL2-18+
Mini-Circuits
10
4000
1:2
TCM2-43X+
Mini-Circuits
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
25
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.3.2.3 DC Coupled Input Usage
When a DC-coupled signal source is used, the common mode voltage of the applied signal must be within a
specified range (VCMI). To achieve this range, the common mode of the driver should be based on the VCMO
output provided for this purpose.
Full-scale distortion performance degrades as the input common-mode voltage deviates from VCMO. Therefore,
maintaining the input common-mode voltage within the VCMI range is important.
Table 2 lists the recommended amplifiers for DC-coupled usage or if AC-coupling with gain is required.
Table 2. Amplifier Recommendations
–3-dB BANDWIDTH (MHz)
MIN GAIN (dB)
MAX GAIN (dB)
GAIN TYPE
PART NUMBER
7000
16
2800
0
16
Fixed
LMH3401
17
Resistor set
2400
LMH6554
6
26
Digital programmable
LMH6881
900
–1.16
38.8
Digital programmable
LMH6518
7.3.2.4 Handling Single-Ended Input Signals
The LM15851 device has no provision to adequately process single-ended input signals. The best way to handle
single-ended signals is to convert these signals to balanced differential signals before presenting the signals to
the ADC.
7.3.3 Clocking
The LM15851 device has a differential clock input, DEVCLK+ and DEVCLK–, that must be driven with an ACcoupled differential clock-signal. The clock inputs are internally terminated and biased. The input clock signal
must be capacitively coupled to the clock pins as shown in Figure 33.
C(couple)
CLK+
C(couple)
CLK±
Figure 33. Differential Sample-Clock Connection
The differential sample-clock line pair must have a characteristic impedance of 100 Ω and must be terminated at
the clock source of that 100-Ω characteristic impedance. The input clock line must be as short and direct as
possible. The LM15851 clock input is internally terminated with an untrimmed 100-Ω resistance.
Insufficient input clock levels results in poor dynamic performance. Excessively-high input-clock levels can cause
a change in the analog-input offset voltage. To avoid these issues, maintain the input clock level within the range
specified in the Electrical Characteristics table.
The low times and high times of the input clock signal can affect the performance of any ADC. The LM15851
device features a duty-cycle clock-correction circuit which maintains performance over temperature. The ADC
meets the performance specification when the input clock high times and low times are maintained as specified
in the Electrical Characteristics table.
High-speed high-performance ADCs such as the LM15851 device require a very-stable input clock-signal with
minimum phase noise or jitter. ADC jitter requirements are defined by the ADC resolution or ENOB (effective
number of bits), maximum ADC input frequency, and the input signal amplitude relative to the ADC input fullscale range. Use Equation 1 to calculate the maximum jitter (the sum of the jitter from all sources) allowed to
prevent a jitter-induced reduction in SNR.
26
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
RMStot(J)
VFSR
1
u
(n
1)
VI(PP)
2
u S u FIN
where
•
•
•
•
•
RMStot(J) is the RMS total of all jitter sources in seconds
VI(PP) is the peak-to-peak analog input signal
VFSR is the full-scale range of the ADC
n is the ADC resolution in bits
FIN is the maximum input frequency, in Hertz, at the ADC analog input
(1)
Note that the maximum jitter previously described is the root sum square (RSS) of the jitter from all sources,
including that from the clock source, the jitter added by noise coupling at board level and that added internally by
the ADC clock circuitry, in addition to any jitter added to the input signal. Because the effective jitter added by the
ADC is beyond user control, the best option is to minimize the jitter from the clock source, the sum of the
externally-added input clock jitter and the jitter added by any circuitry to the analog signal.
Input clock amplitudes above those specified in the Recommended Operating Conditions table can result in
increased input-offset voltage. Increased input-offset voltage causes the converter to produce an output code
other than the expected 2048 when both input pins are at the same potential.
7.3.4 Over-Range Function
To ensure that system-gain management has the quickest-possible response time, a low-latency configurable
over-range function is included. The over-range function works by monitoring the raw 12-bit samples exiting the
ADC module. The upper 8 bits of the magnitude of the ADC data are checked against two programmable
thresholds, OVR_T0 and OVR_T1. The following table lists how a raw ADC value is converted to an absolute
value for a comparison of the thresholds.
ADC SAMPLE
(OFFSET BINARY)
ADC SAMPLE
(2's COMPLEMENT)
ABSOLUTE VALUE
UPPER 8 BITS USED FOR
COMPARISON
1111 1111 1111 (4095)
0111 1111 1111 (+2047)
111 1111 1111 (2047)
1111 1111 (255)
1111 1111 0000 (4080)
0111 1111 0000 (+2032)
111 1111 0000 (2032)
1111 1110 (254)
1000 0000 0000 (2048)
0000 0000 0000 (0)
000 0000 0000 (0)
0000 0000 (0)
0000 0001 0000 (16)
1000 0001 0000 (-2032)
111 1111 0000 (2032)
1111 1110 (254)
0000 0000 0000 (0)
1000 0000 0000 (-2048)
111 1111 1111 (2047)
1111 1111 (255)
If the upper 8 bits of the absolute value equal or exceed the OVR_T0 or OVR_T1 threshold during the monitoring
period, then the over-range bit associated with the threshold is set to 1, otherwise the over-range bit is 0. The
resulting over-range bits are embedded into the complex output data samples and output on OR_T0 and OR_T1.
Table 3 lists the outputs, related data samples, threshold settings and the monitoring period equation.
Table 3. Threshold and Monitor Period for Embedded OR Bits
(1)
EMBEDDED OVER-RANGE
OUTPUTS
ASSOCIATED THRESHOLD
ASSOCIATED SAMPLES
OR_T0
OVR_T0
In-Phase (I) samples
OR_T1
OVR_T1
Quadrature (Q) samples
MONITORING PERIOD
(ADC SAMPLES)
2OVR_N (1)
OVR_N is the monitoring period register setting.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
27
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table 4. Over-Range Monitoring Period
OVR_N
MONITORING PERIOD
0
1
1
2
2
4
3
8
4
16
5
32
6
64
7
128
Typically, the OVR_T0 threshold can be set near the full-scale value (228 for example). When the threshold is
triggered, a typical system can turn down the system gain to avoid clipping. The OVR_T1 threshold can be set
much lower. For example, the OVR_T1 threshold can be set to 64 (−12 dBFS). If the input signal is strong, the
OVR_T1 threshold is tripped occasionally. If the input is quite weak, the threshold is never tripped. The
downstream logic device monitors the OVR_T1 bit. If OVR_T1 stays low for an extended period of time, then the
system gain can be increased until the threshold is occasionally tripped (meaning the peak level of the signal is
above −12 dBFS).
The OR_T0 threshold is embedded as the LSB along with the upper 15 bits of every complex I sample. The
OR_T1 threshold is embedded as the LSB along with the upper 15 bits of every complex Q sample.
7.3.5 ADC Core Features
7.3.5.1 The Reference Voltage
The reference voltage for the LM15851 device is derived from an internal bandgap reference. A buffered version
of the reference voltage is available at the VBG pin for user convenience. This output has an output-current
capability of ±100 μA. The VBG output must be buffered if more current is required. No provision exists for the
use of an external reference voltage, but the full-scale input voltage can be adjusted through the full-scale-range
register settings.
7.3.5.2 Common-Mode Voltage Generation
The internal reference voltage is used to generate a stable common-mode voltage reference for the analog
Inputs and the DEVCLK and SYSREF differential-clock inputs.
7.3.5.3 Bias Current Generation
An external bias resistor, in combination with the on-chip voltage reference is used to provide an accurate and
stable source of bias currents for internal circuitry. Using an external accurate resistor minimizes variation in
device power consumption and performance.
7.3.5.4 Full Scale Range Adjust
The ADC input full-scale range can be adjusted through the GAIN_FS register setting (registers 0x022 and
0x023). The adjustment range is approximately 500 mVPP to 950 mVPP. The full-scale range adjustment is useful
for matching the input-signal amplitude to the ADC full scale, or to match the full-scale range of multiple ADCs
when developing a multi-converter system.
7.3.5.5 Offset Adjust
The ADC-input offset voltage can be adjusted through the OFFSET_FS register setting (registers 0x025 and
0x026). The adjustment range is approximately 28 mV to –28 mV differential.
NOTE
Offset adjust has no effect when background calibration mode is enabled.
28
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.3.5.6 Power-Down
The power-down bit (PD) allows the LM15851 device to be entirely powered down. The serial data output drivers
are disabled when PD is high. When the device returns to normal operation, the JESD204 link must be reestablished, and the ADC pipeline and decimation filters contain meaningless information and must be flushed.
7.3.5.7 Built-In Temperature Monitor Diode
A built-in thermal monitoring diode junction is made available on the TDIODE+ and TDIODE– pins. This diode
facilitates temperature monitoring and characterization of the device in higher ambient temperature
environments. While the on-chip diode is not highly characterized, the diode can be used effectively by
performing a baseline measurement at a known ambient or board temperature with the device in power-down
(PD) mode. Recommended monitoring ICs include the LM95233 device and similar remote-diode temperature
monitoring products from Texas Instruments.
7.3.6 Digital Down Converter (DDC)
The digitized data is the input to the digital down-converter block. This block provides frequency conversion and
decimation filtering to allow a specific range of frequencies to be selected and output in the digital data stream.
7.3.6.1 NCO/Mixer
The DDC contains a complex numerically-controlled oscillator and a complex mixer. The oscillator generates a
complex exponential sequence shown in Equation 2.
x[n] = ejωn
(2)
The frequency (ω) is specified by the a 32-bit register setting. The complex exponential sequence is multiplied by
the real input from the ADC to mix the desired carrier down to 0 Hz.
7.3.6.2 NCO Settings
7.3.6.2.1 NCO Frequency Phase Selection
Within the DDC, eight different frequency and phase settings are always available for use. Each of the eight
settings uses a different phase accumulator within the NCO. Because all eight phase accumulators are
continuously running independently, rapid switching between different NCO frequencies is possible allowing rapid
tuning of different signals.
The specific frequency-phase pair in use is selected through either the NCO_x input pins, or the NCO_SEL
configuration bits (register 0x20D, bits 2:0). The CFG_MODE bit (register 0x20C, bit 0) is used to choose
whether the input pins or selection bits are used. When the CFG_MODE bit is set to 0, the NCO_x input pins
select the active NCO frequency and phase setting. When the CFG_MODE bit is set to 1, the NCO_SEL register
settings select the active NCO frequency and phase setting.
The frequency for each phase accumulator is programmed independently through the NCO_FREQn (and
optionally NCO_RDIV) settings. The phase offset for each accumulator is programmed independently through
the NCO_PHASEn register settings.
7.3.6.2.2 NCO_0, NCO_1, and NCO_2 (NCO_x)
When the CFG_MODE bit is set to 0, the state of these three inputs determines the active NCO frequency and
phase accumulator settings.
7.3.6.2.3 NCO_SEL Bits (2:0)
When the CFG_MODE bit is set to 1, the state of these register bits determines the active NCO frequency and
phase accumulator settings.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
29
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.3.6.2.4 NCO Frequency Setting (Eight Total)
7.3.6.2.4.1 Basic NCO Frequency-Setting Mode
In basic NCO frequency-setting mode, the NCO frequency setting is set by the 32-bit register value,
NCO_FREQn (n = preset 0 trough 7, see the NCO Frequency (Preset x) Register section).
(n = 0 – 7) ƒ(NCO) = NCO_FREQn × 2–32 × ƒ(DEVCLK)
(3)
NOTE
Changing the register setting after the JESD204B interface is running results in nondeterministic NCO phase. If deterministic phase is required, the JESD204B link must be
re-initialized after changing the register setting. See the Multiple ADC Synchronization
section.
7.3.6.2.4.2 Rational NCO Frequency Setting Mode
In basic NCO frequency mode, the frequency step size is very small and many frequencies can be synthesized,
but sometimes an application requires very specific frequencies that fall between two frequency steps. For
example with ƒS equal to 2457.6 MHz and a desired ƒ(NCO) equal to 5.02 MHz the value for NCO_FREQ is
8773085.867. Truncating the fractional portion results in an ƒ(NCO) equal to 5.0199995 MHz, which is not the
desired frequency.
To produce the desired frequency, the NCO_RDIV parameter is used to force the phase accumulator to arrive at
specific frequencies without error. First, select a frequency step size (ƒ(STEP)) that is appropriate for the NCO
frequency steps required. The typical value of ƒ(STEP) is 10 kHz. Next, program the NCO_RDIV value according
to Equation 4.
NCO _ RDIV
§ ¦(DEVCLK) ·
¨
¸
¨ ¦(STEP) ¸
©
¹
128
(4)
The result of Equation 4 must be an integer value. If the value is not an integer, adjust either of the parameters
until the result in an integer value.
For example, select a value of 1920 for NCO_RDIV.
NOTE
NCO_RDIV values larger than 8192 can degrade the NCO SFDR performance and are
not recommended.
Now use Equation 5 to calculate the NCO_FREQ register value.
§ 225 u N ·
NCO _ FREQ round u ¨
¨ NCO _ RDIV ¸¸
©
¹
(5)
Alternatively, the following equations can be used:
¦(NCO)
N
¦(STEP)
(6)
§ 2 u N ·
round u ¨
¨ NCO _ RDIV ¸¸
©
¹
25
NCO _ FREQ
30
(7)
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Table 5. Common NCO_RDIV Values (For 10-kHz Frequency Steps)
ƒ(DEVCLK) (MHz)
NCO_RDIV
3686.4
2880
3072
2400
2949.12
2304
2457.6
1920
1966.08
1536
1474.56
1152
1228.8
960
7.3.6.2.5 NCO Phase-Offset Setting (Eight Total)
The NCO phase-offset setting is set by the 16-bit register value NCO_PHASEn (n = preset 0 trough 7, see the
NCO Phase (Preset x) Register section). The value is left-justified into a 32-bit field and then added to the phase
accumulator.
Use Equation 8 to calculate the phase offset in radians.
NCO_PHASEn × 2–16 × 2 × π
(8)
NOTE
Changing the register setting after the JESD204B interface is running results in nondeterministic NCO phase. If deterministic phase is required, the JESD204B link must be
re-initialized after changing the register setting. See Multiple ADC Synchronization.
7.3.6.2.6 Programmable DDC Delay
The DDC Filter elements incorporate a programmable sample delay. The delay can be programmed from 0 to
(decimation setting – 0.5) ADC sample periods. The delay step-size is 0.5 ADC sample periods. The delay
settings are programmed through the DDC_DLYn parameter.
Table 6. Programmable DDC Delay Range
D (Decimation Setting)
Min Delay (t(DEVCLK))
Max Delay (t(DEVCLK))
4
0
3.5
7.5
8
0
10
0
9.5
16
0
15.5
20
0
19.5
32
0
31.5
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
31
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.3.6.3 Decimation Filters
The decimation filters are arranged to provide a programmable overall decimation of 4, 8, 10, 16, 20, or 32. The
input and output of each filter is complex. The output data consists of 15-bit complex baseband information.
Table 7 lists the effective output sample rates.
Table 7. Output Sample Rates
COMPLEX SAMPLE OUTPUT RATE AND RESULTING BANDWIDTH
(OUTPUT SAMPLE = 15-BIT I + 15-BIT Q + 2-BIT OR)
ƒ(DEVCLK)
DECIMATION
SETTING
OUTPUT RATE
(MSPS)
ƒ(DEVCLK) = 4000 MHz
RAW OUTPUT
BANDWIDTH
(MHz)
ALIAS
PROTECTED
BANDWIDTH
(MHz)
OUTPUT RATE
(MSPS)
RAW OUTPUT
BANDWIDTH
(MHz)
ALIAS
PROTECTED
BANDWIDTH
(MHz)
4
ƒ(DEVCLK) / 4
ƒ(DEVCLK) / 4
0.8 × ƒ(DEVCLK) / 4
1000
1000
800
8
ƒ(DEVCLK) / 8
ƒ(DEVCLK)N / 8
0.8 × ƒ(DEVCLK) / 8
500
500
400
10
ƒ(DEVCLK) / 10
ƒ(DEVCLK) / 10
0.8 × ƒ(DEVCLK) / 10
400
400
320
16
ƒ(DEVCLK) / 16
ƒ(DEVCLK) / 16
0.8 × ƒ(DEVCLK) / 16
250
250
200
20
ƒ(DEVCLK) / 20
ƒ(DEVCLK) / 20
0.8 × ƒ(DEVCLK) / 20
200
200
160
32
ƒ(DEVCLK) / 32
ƒ(DEVCLK) / 32
0.8 × ƒ(DEVCLK) / 32
125
125
100
For maximum efficiency a group of high speed filter blocks are implemented with specific blocks used for each
decimation setting. The first table below describes the combination of filter blocks used for each decimation
setting. The next table lists the coefficient details and decimation factor of each filter block.
Table 8. Decimation Mode Filter Usage
Decimation Setting
32
Filter Blocks Used
4
CS19, CS55
8
CS11, CS15, CS55
10
CS11, CS139
16
CS7, CS11, CS15, CS55
20
CS7, CS11, CS139
32
CS7, CS7, CS11, CS15, CS55
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Table 9. Filter Coefficient Details
Filter Coefficient Set (Decimation Factor of Filter)
CS7 (2)
CS11 (2)
CS15 (2)
CS19 (2)
CS55 (2)
CS139 (5)
–65
–65
109
109
–327
–327
22
22
–37
–37
–5
–5
0
0
0
0
0
0
0
0
0
0
–9
–9
577
577
–837
–837
2231
2231
–174
–174
118
118
–9
–9
0
0
0
0
0
0
0
0
–5
–5
4824
4824
–8881
–8881
744
744
–291
–291
0
0
0
0
0
0
0
0
20
20
39742
39742
–2429
–2429
612
612
33
33
0
0
0
0
33
33
10029
10029
–1159
–1159
21
21
0
0
0
0
2031
2031
–54
–54
1024
8192
65536
16384
0
0
–88
–88
–3356
–3356
–89
–89
0
0
–56
–56
5308
5308
0
0
0
0
119
119
–8140
–8140
196
196
0
0
199
199
12284
12284
125
125
0
0
0
0
–18628
–18628
–234
–234
0
0
–385
–385
29455
29455
–393
–393
0
0
–248
–248
–53191
–53191
0
0
0
0
422
422
166059
166059
696
696
711
711
450
450
262144
0
0
–711
–711
–1176
–1176
–1206
–1206
–766
–766
0
0
1139
1139
1893
1893
1949
1949
1244
1244
0
0
–1760
–1760
–2940
–2940
–3044
–3044
–1955
–1955
0
0
2656
2656
4472
4472
4671
4671
3026
3026
0
0
–3993
–3993
–6802
–6802
–7196
–7196
–4730
–4730
0
0
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
33
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table 9. Filter Coefficient Details (continued)
Filter Coefficient Set (Decimation Factor of Filter)
CS7 (2)
CS11 (2)
CS15 (2)
CS19 (2)
CS55 (2)
CS139 (5)
6159
6159
10707
10707
11593
11593
7825
7825
0
0
–10423
–10423
–18932
–18932
–21629
–21629
–15618
–15618
0
0
24448
24448
52645
52645
78958
78958
97758
97758
104858
7.3.6.4 DDC Output Data
The DDC output data consist of 15-bit complex data plus the two over-range threshold-detection control bits. The
following table lists the data format:
16-BIT OUTPUT WORD
CHANNEL
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
I
DDC Output In-Phase (I) 15 bit
OR_T0
Q
DDC Output Quadrature (Q) 15 bit
OR_T1
7.3.6.5 Decimation Settings
7.3.6.5.1 Decimation Factor
The decimation setting is adjustable over the following settings:
• Decimate-by-4
• Decimate-by-8
• Decimate-by-10
• Decimate-by-16
• Decimate-by-20
• Decimate-by-32
NOTE
Because the output format is complex I+Q, the effective output bandwidth is approximately
two-times the value for a real output with the same decimation factor.
7.3.6.5.2 DDC Gain Boost
The DDC gain boost (register 0x200, bit 4) provides additional gain through the DDC block. With a setting of 1
the final filter has 6.02-dB gain. With a setting of 0, the final filter has a 0-dB gain. This setting is recommended
when the NCO is set near DC.
7.3.7 Data Outputs
The data outputs (DSx±) are very high-speed differential outputs and conform to the JESD204B JEDEC
standard. A CML (current-mode logic)-type output driver is used for each output pair. Output pre-emphasis is
adjustable to compensate for longer PCB-trace lengths.
34
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.3.7.1 The Digital Outputs
The LM15851 output data is transmitted on up to five high-speed serial-data lanes. The output data from the
DDC is formatted to the five lanes, 8b10b encoded, and serialized. Up to four different serial output rates are
possible depending on the decimation mode setting: 1x, 1.25x, 2x, and 2.5x. In 1x mode, the output serializers
run at the same bit rate as the frequency of the applied DEVCLK. In 1.25x mode, the output serializers run at a
bit rate that is 1.25-times that of the applied DEVCLK, and so on. For example, for a 1.6-GHz input DEVCLK, the
output rates are 1.6 Gbps in 1x mode, 2 Gbps in 1.25x mode, 3.2 Gbps in 2x mode and 4 Gbps in 2.5x mode.
7.3.7.2 JESD204B Interface Features and Settings
7.3.7.2.1 Scrambler Enable
Scrambling randomizes the 8b10b encoded data, spreading the frequency content of the data interface. This
reduces the peak EMI energy at any given frequency reducing the possibility of feedback to the device inputs
impacting performance. The scrambler is disabled by default and is enabled via SCR (register 0x201, bit 7).
7.3.7.2.2 Frames Per Multi-Frame (K-1)
The frames per multi-frame (K) setting can be adjusted within constraints that are dependant on the selected
decimation (D) and serial rate (DDR) settings. The K-minus-1 (KM1) register setting (register 0x201, bits 6:2)
must be one less than the desired K setting.
7.3.7.2.3 DDR
The serial rate can be either 1ƒ(CLK) (DDR = 0) or 2ƒ(CLK) (DDR = 1).
7.3.7.2.4 JESD Enable
The JESD interface must be disabled (JESD_EN is set to 0) while any of the other JESD parameters are
changed. While JESD_EN is set 0 the block is held in reset and the serializers are powered down. The clocks for
this section are also gated off to further save power. When the parameters have been set as desired the JESD
block can be enabled (JESD_EN is set to 1).
7.3.7.2.5 JESD Test Modes
Several different JESD204B test modes are available to assist in link verification and debugging. The list of
modes follows.
NOTE
PRBS test signals are output directly, without 8b10b encoding.
•
•
•
•
•
•
•
•
•
•
•
•
Normal operation
PRBS7 test mode
PRBS15 test mode
PRBS23 test mode
Ramp test mode
Short or long transport-layer test mode
D21.5 test mode
K28.5 test mode
Repeated ILA test mode
Modified RPAT test mode
Serial-outputs differential 0 test mode
Serial-outputs differential 1 test mode
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
35
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.3.7.2.6 Configurable Pre-Emphasis
The high-speed serial-output drivers incorporate a configurable pre-emphasis feature. This feature allows the
output drive waveform to be optimized for different PCB materials and signal transmission distances. The preemphasis setting is adjusted through the serializer pre-emphasis setting in register 0x040, bits 3 to 0. The default
setting is 4d. Higher values will increase the pre-emphasis to compensate for more lossy PCB materials. This
adjustment is best used in conjunction with an eye-diagram analysis capability in the receiver. The pre-emphasis
setting should be adjusted to optimize the eye-opening for the hardware configuration and line rates needed.
7.3.7.2.7 Serial Output-Data Formatting
Output data is generated by the DDC then formatted according to the selected decimation and output rate
settings. When less than the maximum of five lanes are active, lanes are disabled beginning with the highest
numerical lanes. For example when only two lanes are active, lanes 0 and 1 are active, while all higher lanes are
inactive.
Table 10. Parameter Definitions
PARAMETER
D
DESCRIPTION
USER
CONFIGURED
OR DERIVED
STANDARD
JESD204B LINK
PARAMETER
No
Decimation factor, determined by DMODE register
User
DDR
Serial line rate: 1 = DDR rate (2x), 0 = SDR rate (1x)
User
No
P54
Enable 5/4 PLL to increase line rate by 1.25x.
User
No
0 = no PLL (1x), 1 = enable PLL (1.25x)
K
Number of frames per multiframe
User
Yes
N
Bits per sample (before adding control bits and tails bits)
Derived
Yes
CS
Control bits per sample
Derived
Yes
N’
Bits per sample (after adding control bits and tail bits). Must be a multiple of
4.
Derived
Yes
L
Number of serial lanes
Derived
Yes
F
Number of octets (bytes) per frame (per lane)
Derived
Yes
M
Number of (logical) converters
Derived
Yes
S
Number of samples per converter per frame
Derived
Yes
CF
Number of control words per frame
Derived
Yes
HD
1=High density mode (samples may be broken across lanes), 0 = normal
mode (samples may not be broken across lanes)
Derived
Yes
KS
Legal adjustment step for K, to ensure that the multi-frame clock is a subharmonic of other internal clocks
Derived
No
Table 11. Serial Link Parameters (1)
USER SPECIFIED PARAMETERS
DERIVED PARAMETERS
OTHER INFORMATION
DECIMATION
FACTOR (D)
DDR
P54
N
CS
N’
L
F
M
S
KS
4
1
0
15
1
16
5
4
2
5
4
8-32
2x
4
1
1
15
1
16
4
2
2
2
2
10-32
2.5x
8
0
0
15
1
16
5
4
2
5
2
6-32
1x
8
0
1
15
1
16
4
2
2
2
1
9-32
1.25x
8
1
0
15
1
16
3
8
2
5
2
4-32
2x
8
1
1
15
1
16
2
2
2
1
2
10-32
2.5x
10
0
0
15
1
16
4
2
2
2
4
12-32
1x
10
1
0
15
1
16
2
2
2
1
8
16-32
2x
16
0
0
15
1
16
3
8
2
5
1
3-32
1x
16
0
1
15
1
16
2
2
2
1
1
9-32
1.25x
16
1
0
15
1
16
2
16
2
5
1
2-32
2x
(1)
(2)
In all modes: HD = 0 and CF = 0
x = times (for example, 2x = 2-times)
36
Submit Documentation Feedback
LEGAL K
RANGE
BIT RATE / ADC
CLOCK (2)
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Table 11. Serial Link Parameters(1) (continued)
USER SPECIFIED PARAMETERS
DERIVED PARAMETERS
OTHER INFORMATION
DECIMATION
FACTOR (D)
LEGAL K
RANGE
DDR
P54
N
CS
N’
L
F
M
S
KS
BIT RATE / ADC
CLOCK (2)
16
1
1
15
1
16
1
4
2
1
20
0
0
15
1
16
2
2
2
1
1
5-32
2.5x
4
12-32
20
1
0
15
1
16
1
4
2
1x
1
4
8-32
32
0
0
15
1
16
2
16
2x
2
5
1
2-32
32
0
1
15
1
16
1
1x
4
2
1
1
5-32
1.25x
32
1
0
15
1
16
1
32
2
5
1
1-32
2x
Output data is formatted in a specific optimized fashion for each decimation and DDR setting combination. The
following tables list the specific mapping formats. In all mappings the T or tail bits are 0 (zero).
Table 12. Decimate-by-4, DDR = 1, P54 = 0, LMF = 5,2,4
TIME →
CHAR NUMBER
0
1
2
3
Lane 0
I0
I1
Lane 1
I2
I3
Lane 2
I4
Q0
Lane 3
Q1
Q2
Lane 4
Q3
Q4
Frame n
Table 13. Decimate-by-4, DDR = 1, P54 = 1, LMF = 4,2,2
TIME →
CHAR NUMBER
Lane 0
0
1
2
I0
3
4
5
I2
I4
Lane 1
I1
I3
I5
Lane 2
Q0
Q2
Q4
Lane 3
Q1
Q3
Q5
Frame
n
Frame
n+1
Frame
n+2
Table 14. Decimate-by-8, DDR = 0, P54 = 0, LMF = 5,2,4
TIME →
CHAR NUMBER
0
1
2
3
Lane 0
I0
I1
Lane 1
I2
I3
Lane 2
I4
Q0
Lane 3
Q1
Q2
Lane 4
Q3
Q4
Frame n
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
37
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table 15. Decimate-by-8, DDR = 0, P54 = 1, LMF = 4,2,2
TIME →
CHAR NUMBER
0
1
2
3
4
5
Lane 0
I0
I2
Lane 1
I1
I3
I4
I5
Lane 2
Q0
Q2
Q4
Lane 3
Q1
Q3
Q5
Frame
n
Frame
n+1
Frame
n+2
Table 16. Decimate-by-8, DDR = 1, P54 = 0, LMF = 3,2,8
TIME →
CHAR NUMBER
0
Lane 0
1
2
3
4
5
6
7
I0
I1
I2
I3
Lane 1
I4
Q0
Q1
Q2
Lane 2
Q3
Q4
T
T
Frame n
Table 17. Decimate-by-8, DDR = 1, P54=1, LMF = 2,2,2
TIME →
CHAR NUMBER
0
1
2
3
4
5
Lane 0
I0
I1
I2
Lane 1
Q0
Q1
Q2
Frame
n
Frame
n+1
Frame
n+2
Table 18. Decimate-by-10, DDR = 0, P54 = 0, LMF = 4,2,2
TIME →
CHAR NUMBER
0
Lane 0
1
2
I0
3
4
I2
5
6
I4
7
I6
Lane 1
I1
I3
I5
I7
Lane 2
Q0
Q2
Q4
Q6
Lane 3
Q1
Q3
Q5
Q7
Frame
n
Frame
n+1
Frame
n+2
Frame
n+3
Table 19. Decimate-by-10, DDR = 1, P54 = 0, LMF = 2,2,2
TIME →
CHAR NUMBER
0
1
2
3
4
5
6
7
Lane 0
I0
I1
I2
I3
Lane 1
Q0
Q1
Q2
Q3
Frame
n
Frame
n+1
Frame
n+2
Frame
n+3
38
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Table 20. Decimate-by-16, DDR = 0, P54 = 0, LMF = 3,2,8
TIME →
CHAR NUMBER
0
1
2
3
4
5
6
7
Lane 0
I0
I1
I2
I3
Lane 1
I4
Q0
Q1
Q2
Lane 2
Q3
Q4
T
T
Frame n
Table 21. Decimate-by-16, DDR = 0, P54 = 1, LMF = 2,2,2
TIME →
CHAR NUMBER
0
1
Lane 0
2
3
I0
Lane 1
4
5
I1
I2
Q0
Q1
Q2
Frame
n
Frame
n+1
Frame
n+2
Table 22. Decimate-by-16, DDR = 1, P54 = 0, LMF = 2,2,16
TIME →
CHAR
NUMBER
0
1
2
3
4
5
6
7
Lane 0
I0
I1
I2
I3
Lane 1
Q3
Q4
T
T
8
9
10
11
12
13
14
15
I4
Q0
Q1
Q2
T
T
T
T
Frame n
Table 23. Decimate-by-16, DDR = 1, P54 = 1, LMF = 1,2,4
TIME →
CHAR NUMBER
Lane 0
0
1
2
I0
3
4
Q0
5
6
I1
Frame n
7
8
Q1
9
10
I2
Frame n + 1
11
Q2
Frame n + 2
Table 24. Decimate-by-20, DDR = 0, P54 = 0, LMF = 2,2,2
TIME →
CHAR NUMBER
0
1
2
3
4
5
6
7
Lane 0
I0
I1
I2
I3
Lane 1
Q0
Q1
Q2
Q3
Frame
n
Frame
n+1
Frame
n+2
Frame
n+3
Table 25. Decimate-by-20, DDR = 1, P54 = 0, LMF = 1,2,2
TIME →
CHAR NUMBER
Lane 0
0
1
2
I0
3
Q0
Frame n
4
5
6
I1
7
Q1
Frame n + 1
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
39
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table 26. Decimate-by-32, DDR = 0, P54 = 0, LMF = 2,2,16
TIME →
CHAR
NUMBER
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Lane 0
I0
I1
I2
I3
I4
Q0
Q1
Q2
Lane 1
Q3
Q4
T
T
T
T
T
T
Frame n
Table 27. Decimate-by-32, DDR = 0, P54 = 1, LMF = 1,2,4
TIME →
CHAR NUMBER
0
1
Lane 0
2
3
I0
4
5
Q0
6
I1
7
8
9
Q1
Frame n
10
11
I2
Q2
Frame n + 1
Frame n + 2
Table 28. Decimate-by-32, DDR = 1, P54 = 0, LMF = 1,2,32
TIME →
CHAR
NUMBE
R
Lane 0
0
1
I0
2
3
I1
4
5
I2
6
7
I3
8
9
I4
10
11
Q0
12
13
Q1
14
15
Q2
16
17
Q3
18
19
20
Q4
21
T
22
23
T
24
25
T
26
27
T
28
29
T
30
31
T
Frame n
The formatted data is 8b10b encoded and output on the serial lanes. The 8b10b encoding provides a number of
specific benefits, including:
• Standard encoding format. Therefore the IP is readily available in off-the-shelf FPGAs and ASIC building
blocks.
• Inherent DC balance allows AC coupling of lanes with small on-chip capacitors
• Inherent error checking
7.3.7.2.8 JESD204B Synchronization Features
The JESD204B standard defines methods for synchronization and deterministic latency in a multi-converter
system. This device is a JESD204B Subclass 1 device and conforms to the various aspects of link operation as
described in section 5.3.3 of the JESD204B standard. The specific signals used to achieve link operation are
described briefly in the following sections.
7.3.7.2.9 SYSREF
The SYSREF is a periodic signal which is sampled by the device clock, and is used to align the boundary of the
local multi-frame clock inside the data converter. SYSREF
is required to be a sub-harmonic of the LMFC internal timing. To meet this requirement, the timing of SYSREF is
dependent on the device clock frequency and the LMFC frequency as determined by the selected DDC
decimation and frames per multi-frame settings. This clock is typically in the range of 10 MHz to 300 MHz. See
the Multiple ADC Synchronization section for more details on SYSREF timing requirements.
7.3.7.2.10 SYNC~
SYNC~ is asserted by the receiver to initiate a synchronization event.
Single ended and differential SYNC~ inputs are provided. The SYNC_DIFFSEL bit (register 0x202, bit 6) is used
to select which input is used. . To assert SYNC~, a logic low is applied. To deassert SYNC~ a logic high is
applied.
7.3.7.2.11 Code-Group Synchronization
Code-group synchronization is achieved using the following process:
• The receiver issues a synchronization request through the SYNC~ input
• The transmitter issues a stream of K28.5 symbols
40
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
•
•
•
•
SLAS990D – JANUARY 2014 – REVISED JULY 2015
The receiver synchronizes and waits for correct reception of at least 4 consecutive K symbols
The receiver deactivates the synchronization request
Upon detecting that the receiver has deactivated the SYNC~ pin, the transmitter continues emitting K symbols
until the next LMFC boundary (or optionally a later LMFC boundary)
On the first frame following the selected LMFC boundary the transmitters emit an initial lane-alignment
sequence
The initial-lane alignment sequence transmitted by the ADC device is defined in additional detail in JESD204B
section 5.3.3.5.
7.3.7.2.12 Multiple ADC Synchronization
The second function for the SYSREF input is to facilitate the precise synchronization of multiple ADCs in a
system.
One key challenge is to ensure that this synchronization works is to ensure that the SYSREF inputs are
repeatedly captured by the input CLK. Two key elements must occur for the SYSREF inputs to be captured.
First, the SYSREF input must be created so that it is synchronous to the input DEVCLK, be an integer subharmonic of the multi-frame (K × t(FRAME)) and a repeatable and fixed-phase offset. When this constraint is
achieved, repeatedly capturing SYSREF is easier. To further ease this task, the SYSREF signal is routed
through a user-adjustable delay which eases the timing requirements with respect to the input DEVCLK signal.
The SYSREF delay RDEL is adjusted through bits 3 through 0 in register 0x032.
As long as the SYSREF signal has a fixed timing relationship to DEVCLK, the internal delay can be used to
maximize the setup and hold times between the internally delayed SYSREF and the internal DEVCLK signal.
These timing relationships are listed in the Timing Requirements table. To find the proper delay setting, the
RDEL value is adjusted from minimum to maximum while applying SYSREF and monitoring the SysRefDet and
Dirty Capture detect bits. The SysRefDet bit is set whenever a rising edge of SYSREF is detected. The Dirty
Capture bit is set whenever the setup or hold time between DEVCLK and the delayed SYSREF is insufficient.
The SysRefDetClr bit is used to clear the SysRefDet bit. The Clear Dirty Capture bit is used to clear that bit.
This procedure should be followed to determine the range of delay settings where a clean SYSREF capture is
achieved. The delay value at the center of the clean capture range must be loaded as the final RDEL setting.
Table 29 lists a summary of the control bits that are used and the monitor bits that are read.
Table 29. SYSREF Capture Control and Status
BIT NAME
REGISTER ADDRESS
REGISTER BIT
RDEL
0x032
3:0
FUNCTION
Adjust relative delay between DEVCLK and SYSREF
SysRefDet
0x031
7
Detect if a SYSREF rising edge has been captured (not self clearing)
Dirty Capture
0x031
6
Detect if SYSREF rising edge capture failed setup/hold (not self clearing)
SysRefDetClr
0x030
5
Clear SYSREF detection bit
Clear Dirty Capture
0x030
4
Clear Dirty Capture detection bit
SysRef_Rcvr_En
0x030
7
Enable SYSREF receiver. See the CLKGEN_0 descriptions in the Clock Generator Control 0 Register section
for more information.
SysRef_Pr_En
0x030
6
Enable SYSREF processing. See the CLKGEN_0 descriptions in the Clock Generator Control 0 Register
section for more information.
One final aspect of multi-device synchronization relates to phase alignment of the NCO phase accumulators
when DDC modes are enabled. The NCO phase accumulators are reset during the ILA phase of link startup
which means that for multiple ADCs to have NCO phase alignment, all links must be enabled in the same LMFC
period. Enabling all links in the same LMFC period requires synchronizing the SYNC~ de-assertion across all
data receivers in the system, so that all of the SYNC~ signals are released during the same LMFC period. Using
large K values and resulting longer LMFC periods will ease this task, at the expense of potentially higher latency
in the receiving device.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
41
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.4 Device Functional Modes
7.4.1 DDC Modes
In the DDC modes (decimation > 1) complex (I,Q) data is output at a lower sample rate as determined by the
decimation factor (4, 8, 10, 16, 20, and 32).
7.4.2 Calibration
Calibration adjusts the ADC core to optimize the following device parameters:
• ADC core linearity
• ADC core-to-core offset matching
• ADC core-to-core full-scale range matching
• ADC core 4-way interleave timing
All calibration processes occur internally. Calibration does not require any external signals to be present and
works properly as long as the device is maintained within the values listed in the Recommended Operating
Conditions table.
7.4.2.1 Foreground Calibration Mode
In foreground mode the calibration process interrupts normal ADC operation and no output data is available
during this time (the output code is forced to a static value). The calibration process should be repeated if the
device temperature changes by more than 20ºC to ensure rated performance is maintained. Foreground
calibration is initiated by setting the CAL_SFT bit (register 0x050, bit 3) which is self clearing. The foreground
calibration process finishes within t(CAL) number of DEVCLK cycles. The process occurs somewhat longer when
the timing calibration mode is enabled.
NOTE
Initiating a foreground calibration asynchronously resets the calibration control logic and
may glitch internal device clocks. Therefore after setting the CAL_SFT bit clearing and
then setting JESD_EN is necessary. If resetting the JESD204B link is undesirable for
system reasons, background calibration mode may be preferred.
7.4.2.2 Background Calibration Mode
In background mode an additional ADC core is powered-up for a total of 5 ADC cores. At any given time, one
core is off-line and not used for data conversion. This core is calibrated in the background and then placed online simultaneous with another core going off-line for calibration. This process operates continuously without
interrupting data flow in the application and ensures that all cores are optimized in performance regardless of any
changes of temperature. The background calibration cycle rate is fixed and is not adjustable by the user.
Because of the additional circuitry active in background calibration mode, a slight degradation in performance
occurs in comparison to foreground calibration mode at a fixed temperature. As a result of this degradation, using
foreground calibration mode is recommended if the expected change in operating temperature is <30°C. Using
background calibration mode is recommended if the expected change in operating temperature is >30°C. The
exact difference in performance is dependent on the DEVCLK (sampling clock) frequency, and the analog input
signal frequency and amplitude. For this reason, device and system performance should be evaluated using both
calibration modes before finalizing the choice of calibration mode.
To enable the background calibration feature, set the CAL_BCK bit (register 0x057, bit 0) and the CAL_CONT bit
(register 0x057, bit 1). The value written to the register 0x057 to enable background calibration is therefore
0x013h. After writing this value to register 0x057, set the CAL_SFT bit in register 0x050 to perform the one-time
foreground calibration to begin the process.
NOTE
The ADC offset-adjust feature has no effect when background calibration mode is
enabled.
42
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Device Functional Modes (continued)
7.4.3 Timing Calibration Mode
The timing calibration process optimizes the matching of sample timing for the 4 internally interleaved converters.
This process minimize the presence of any timing related interleaving spurs in the captured spectrum. The timing
calibration feature is disabled by default, but using this feature is highly recommended. To enable timing
calibration, set the T_AUTO bit (register 0x066, bit 0). When this bit is set, the timing calibration performs each
time the CAL_SFT bit is set.
Table 30. Calibration Cycle Timing for Different Calibration Modes and Options
CAL_CONT, CAL_BCK
T_AUTO
LOW_SIG_EN
INITIAL ONE-TIME
CALIBRATION
CAL_SFT 0 → 1
(tDEVCLK)
0
0
0
102 E+6
N/A
0
0
1
64 E+6
N/A
0
1
0
227 E+6
N/A
0
1
1
189 E+6
N/A
1
0
0
127.5 E+6
816 E+6
1
0
1
80 E+6
512 E+6
1
1
0
283.75 E+6
816 E+6
1
1
1
236.25 E+6
512 E+6
(1)
BACKGROUND
CALIBRATION CYCLE (1)
(ALL CORES)
(tDEVCLK)
N/A = not applicable
7.4.4 Test-Pattern Modes
A number of device test modes are available. These modes insert known patterns of information into the device
data path for assistance with system debug, development, or characterization.
7.4.4.1 Serializer Test-Mode Details
Test modes are enabled by setting the appropriate configuration of the JESD204B_TEST setting (Register
0x202, Bits 3:0). Each test mode is described in detail in the following sections. Regardless of the test mode, the
serializer outputs are powered up based on the configuration decimation and DDR settings. The test modes
should only be enabled while the JESD204B link is disabled.
ADC
DDC
JESD204B
Transport Layer
Scrambler
JESD204B
Link Layer
8b10b
Encoder
JESD204B
TX
Active Lanes and Serial Rates
Set by D, DDR, and P54 Parameters
ADC
Test Pattern Enable
Long or Short Transport
Octet Ramp
Test Mode Enable
Repeated ILA
Modified RPAT
Test Mode Enable
PRBSn
D21.5
K28.5
Serial Outputs High/Low
Test Mode Enable
Figure 34. Test-Mode Insertion Points
7.4.4.2 PRBS Test Modes
The PRBS test modes bypass the 8B10B encoder. These test modes produce pseudo-random bit streams that
comply with the ITU-T O.150 specification. These bit streams are used with lab test equipment that can selfsynchronize to the bit pattern and therefore the initial phase of the pattern is not defined.
The sequences are defined by a recursive equation. For example, the PRBS7 sequence is defined as shown in
Equation 9.
y[n] = y[n – 6]y[n – 7]
where
•
Bit n is the XOR of bit [n – 6] and bit [n – 7] which are previously transmitted bits
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
(9)
43
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Table 31. PBRS Mode Equations
PRBS TEST MODE
SEQUENCE
PRBS7
y[n] = y[n – 6]y[n – 7]
SEQUENCE LENGTH (bits)
127
y[n – 15]
PRBS15
y[n] = y[n – 14]
32767
PRBS23
y[n] = y[n – 18]y[n – 23]
8388607
The initial phase of the pattern is unique for each lane.
7.4.4.3 Ramp Test Mode
In the ramp test mode, the JESD204B link layer operates normally, but the transport layer is disabled and the
input from the formatter is ignored. After the ILA sequence, each lane transmits an identical octet stream that
increments from 0x00 to 0xFF and repeats.
7.4.4.4 Short and Long-Transport Test Mode
The long-transport test mode is available in all DDC modes (decimation > 1). Patterns are generated in
accordance with the JESD204B standard and are different for each output format.
Table 32 lists one example of the long transport test pattern:
Table 32. Long Transport Test Pattern - Decimate-by-4, DDR = 1, P54 = 1, K=10
TIME →
CHAR
NO.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Lane 0
0x0003
0x0002
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x0003
Lane 1
0x0002
0x0005
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x0002
Lane 2
0x0004
0x0002
0x8001
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x0004
Lane 3
0x0004
0x0004
0x8000
0x8001
0x8000
0x8000
0x8000
0x8000
0x8000
0x8000
0x0004
Frame
n
Frame
n+1
Frame
n+2
Frame
n+3
Frame
n+4
Frame
n+5
Frame
n+6
Frame
n+7
Frame
n+8
Frame
n+9
Frame
n + 10
If multiple devices are all programmed to the transport layer test mode (while JESD_EN = 0), then JESD_EN is
set to 1, and then SYSREF is used to align the LMFC of the devices, the patterns will be aligned to the SYSREF
event (within the skew budget of JESD204B). For more details see JESD204B, section 5.1.6.3.
7.4.4.5 D21.5 Test Mode
In this test mode, the controller transmits a continuous stream of D21.5 characters (alternating 0s and 1s).
7.4.4.6 K28.5 Test Mode
In this test mode, the controller transmits a continuous stream of K28.5 characters.
7.4.4.7 Repeated ILA Test Mode
In this test mode, the JESD204B link layer operates normally with one exception: when the ILA sequence
completes, the sequence repeats indefinitely. Whenever the receiver issues a synchronization request, the
transmitter will initiate code group synchronization. Upon completion of code group synchronization, the
transmitter will repeatedly transmit the ILA sequence. If there is no active code group synchronization request at
the moment the transmitter enters the test mode, the transmitter will behave as if it received one.
7.4.4.8 Modified RPAT Test Mode
A 12-octet repeating pattern is defined in INCITS TR-35-2004. The purpose of this pattern is to generate white
spectral content for JESD204B compliance and jitter testing. Table 33 lists the pattern before and after 8b10b
encoding.
44
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Table 33. Modified RPAT Pattern Values
OCTET NUMBER
Dx.y NOTATION
8-BIT INPUT TO 8b10b ENCODER
0
D30.5
0xBE
1
D23.6
0xD7
2
D3.1
0x23
3
D7.2
0x47
4
D11.3
0x6B
5
D15.4
0x8F
6
D19.5
0xB3
7
D20.0
0x14
8
D30.2
0x5E
9
D27.7
0xFB
10
D21.1
0x35
11
D25.2
0x59
20b OUTPUT OF 8b10b ENCODER
(2 CHARACTERS)
0x86BA6
0xC6475
0xD0E8D
0xCA8B4
0x7949E
0xAA665
7.5 Programming
7.5.1 Using the Serial Interface
The serial interface is accessed using the following four pins: serial clock (SCLK), serial-data in (SDI), serial-data
out (SDO), and serial-interface chip-select (SCS). Registers access is enabled through the SCS pin.
SCS
This signal must be asserted low to access a register through the serial interface. Setup and hold
times with respect to the SCLK must be observed.
SCLK
Serial data input is accepted at the rising edge of this signal. SCLK has no minimum frequency
requirement.
SDI
Each register access requires a specific 24-bit pattern at this input. This pattern consists of a readand-write (R/W) bit, register address, and register value. The data is shifted in MSB first. Setup and
hold times with respect to the SCLK must be observed (see Figure 2).
SDO
The SDO signal provides the output data requested by a read command. This output is high
impedance during write bus cycles and during the read bit and register address portion of read bus
cycles.
Each register access consists of 24 bits, as shown in Figure 2. The first bit is high for a read and low for a write.
The next 15 bits are the address of the register that is to be written to. During write operations, the last 8 bits are
the data written to the addressed register. During read operations, the last 8 bits on SDI are ignored, and, during
this time, the SDO outputs the data from the addressed register. The serial protocol details are illustrated in
Figure 35.
Single Register Access
SCS
1
8
16
17
A0
D7
24
SCLK
Command Field
SDI
R/W A14 A13 A12 A11 A10 A9
A8
A7
A6
Data Field
A5
A4
A3
A2
A1
D6
D5
D4
D3
D2
D1 D0
Data Field
SDO
(read mode)
Hi Z
D7
D6
D5
D4
D3
D2
D1 D0
Hi Z
Figure 35. Serial Interface Protocol - Single Read / Write
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
45
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Programming (continued)
7.5.1.1 Streaming Mode
The serial interface supports streaming reads and writes. In this mode, the initial 24 bits of the transaction
specifics the access type, register address, and data value as normal. Additional clock cycles of write or read
data are immediately transferred, as long as the SCS input is maintained in the asserted (logic low) state. The
register address auto increments (default) or decrements for each subsequent 8 bit transfer of the streaming
transaction. The ADDR_ASC bit (register 000h, bits 5 and 2) controls whether the address value ascends
(increments) or descends (decrements). Streaming mode can be disabled by setting the ADDR_STATIC bit
(register 010h, bit 0). The streaming mode transaction details are shown in Figure 36.
Multiple Register Access
SCS
8
1
16
17
A0
D7
24
32
25
SCLK
Command Field
SDI
SDO
(read mode)
R/W A14 A13 A12 A11 A10 A9
A8
A7
A6
Data Field (write mode)
A5
A4
A3
A2
A1
D6
D5
D4
D3
D2
D1
Data Field (write mode)
D0
D7
D6
D5
D4
Data Field
Hi Z
D7
D6
D5
D4
D3
D2
D3
D2
D1
D0
Data Field
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
Hi Z
Figure 36. Serial Interface Protocol - Streaming Read / Write
See the Register Map section for detailed information regarding the registers.
NOTE
The serial interface must not be accessed during calibration of the ADC. Accessing the
serial interface during this time impairs the performance of the device until the device is
calibrated correctly. Writing or reading the serial registers also reduces dynamic
performance of the ADC for the duration of the register access time.
46
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6 Register Map
Several groups of registers provide control and configuration options for this device. Each following register
description also shows the power-on reset (POR) state of each control bit.
NOTE
All multi-byte registers are arranged in little-endian format (the least-significant byte is
stored at the lowest address) unless explicitly stated otherwise.
Memory Map
Address
Reset
Type
Register
Standard SPI-3.0 (0x000 to 0x00F)
0x000
0x3C
R/W
Configuration A Register
0x001
0x002
0x00
R
Configuration B Register
0x00
R/W
0x003
0x03
R
Chip Type Register
0x004-0x005
Undefined
R
RESERVED
0x006
0x03
R
Chip Version Register
0x007-0x00B
Undefined
R
RESERVED
0x00C-0x00D
0x0451
R
Vendor Identification Register
0x00E-0x00F
Undefined
R
RESERVED
Device Configuration Register
User SPI Configuration (0x010 to 0x01F)
0x010
0x00
R/W
0x011-0x01F
Undefined
R
User SPI Configuration Register
RESERVED
General Analog, Bias, Band Gap, and Track and Hold (0x020 to 0x02F)
0x020
0x9D
R/W
RESERVED
0x021
0x00
R/W
Power-On Reset Register
0x022
0x40
R/W
I/O Gain 0 Register
0x023
0x00
R/W
I/O Gain 1 Register
0x024
0x00
R/W
RESERVED
0x025
0x40
R/W
I/O Offset 0 Register
0x026
0x00
R/W
I/O Offset 1 Register
0x027
0x06
R/W
RESERVED
0x028
0xBA
R/W
RESERVED
0x029
0xD4
R/W
RESERVED
0x02A
0xEA
R/W
RESERVED
0x02B-0x02F
Undefined
R
RESERVED
Clock (0x030 to 0x03F)
0x030
0xC0
R/W
Clock Generator Control 0 Register
0x031
0x07
R
0x032
0x80
R/W
Clock Generator Control 2 Register
0x033
0xC3
R/W
Analog Miscellaneous Register
0x034
0x2F
R/W
Input Clamp Enable Register
0x035
0xDF
R/W
RESERVED
0x036
0x00
R/W
RESERVED
0x037
0x45
R/W
RESERVED
0x038-0x03F
Undefined
R/W
Clock Generator Status Register
RESERVED
Serializer (0x040 to 0x04F)
0x040
0x04
R/W
0x041-0x04F
Undefined
R
Serializer Configuration Register
RESERVED
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
47
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Register Map (continued)
Memory Map (continued)
Address
Reset
Type
Register
ADC Calibration (0x050 to 0x1FF)
0x050
0x06
R/W
Calibration Configuration 0 Register
0x051
0xF4
R/W
Calibration Configuration 1 Register
0x052
0x00
R/W
RESERVED
0x053
0x5C
R/W
RESERVED
0x054
0x1C
R/W
RESERVED
0x055
0x92
R/W
RESERVED
0x056
0x20
R/W
RESERVED
0x057
0x10
R/W
Calibration Background Control Register
0x058
0x00
R/W
ADC Pattern and Over-Range Enable Register
0x059
0x00
R/W
RESERVED
0x05A
0x00
R/W
Calibration Vectors Register
0x05B
Undefined
R
Calibration Status Register
0x05C
0x00
R/W
RESERVED
0x05D-0x05E
Undefined
R/W
RESERVED
0x05F
0x00
R/W
RESERVED
0x060
Undefined
R
RESERVED
0x061
Undefined
R
RESERVED
0x062
Undefined
R
RESERVED
0x063
Undefined
R
RESERVED
0x064
Undefined
R
RESERVED
0x065
Undefined
R
RESERVED
0x066
0x02
R/W
Timing Calibration Register
0x067
0x01
R/W
RESERVED
0x068
Undefined
R
RESERVED
0x069
Undefined
R
RESERVED
0x06A
0x00
R/W
RESERVED
0x06B
0x20
R/W
RESERVED
0x06C-0x1FF
Undefined
R
RESERVED
Digital Down Converter and JESD204B (0x200-0x27F)
0x200
0x10
R/W
Digital Down-Converter (DDC) Control
0x201
0x0F
R/W
JESD204B Control 1
0x202
0x00
R/W
JESD204B Control 2
0x203
0x00
R/W
JESD204B Device ID (DID)
0x204
0x00
R/W
JESD204B Control 3
0x205
Undefined
R/W
JESD204B and System Status Register
0x206
0xF2
R/W
Overrange Threshold 0
0x207
0xAB
R/W
Overrange Threshold 1
0x208
0x00
R/W
Overrange Period
0x209-0x20B
0x00
R/W
RESERVED
0x20C
0x00
R/W
DDC Configuration Preset Mode
0x20D
0x00
R/W
DDC Configuration Preset Select
0x20E-0x20F
0x0000
R/W
Rational NCO Reference Divisor
0x210-0x213
0xC0000000
R/W
NCO Frequency (Preset 0)
0x214-0x215
0x0000
R/W
NCO Phase (Preset 0)
PRESET 0
48
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Register Map (continued)
Memory Map (continued)
Address
Reset
Type
0x216
0xFF
R/W
DDC Delay (Preset 0)
Register
0x217
0x00
R/W
RESERVED
PRESET 1
0x218-0x21B
0xC0000000
R/W
NCO Frequency (Preset 1)
0x21C-0x21D
0x0000
R/W
NCO Phase (Preset 1)
0x21E
0xFF
R/W
DDC Delay (Preset 1)
0x21F
0x00
R/W
RESERVED
0x220-0x223
0xC0000000
R/W
NCO Frequency (Preset 2)
0x224-0x225
0x0000
R/W
NCO Phase (Preset 2)
0x226
0xFF
R/W
DDC Delay (Preset 2)
0x227
0x00
R/W
RESERVED
PRESET 2
PRESET 3
0x228-0x22B
0xC0000000
R/W
NCO Frequency (Preset 3)
0x22C-0x22D
0x0000
R/W
NCO Phase (Preset 3)
0x22E
0xFF
R/W
DDC Delay (Preset 3)
0x22F
0x00
R/W
RESERVED
0x230-0x233
0xC0000000
R/W
NCO Frequency (Preset 4)
0x234-0x235
0x0000
R/W
NCO Phase (Preset 4)
0x236
0xFF
R/W
DDC Delay (Preset 4)
0x237
0x00
R/W
RESERVED
PRESET 4
PRESET 5
0x238-0x23B
0xC0000000
R/W
NCO Frequency (Preset 5)
0x23C-0x23D
0x0000
R/W
NCO Phase (Preset 5)
0x23E
0xFF
R/W
DDC Delay (Preset 5)
0x23F
0x00
R/W
RESERVED
0x240-0x243
0xC0000000
R/W
NCO Frequency (Preset 6)
0x244-0x245
0x0000
R/W
NCO Phase (Preset 6)
0x246
0xFF
R/W
DDC Delay (Preset 6)
0x247
0x00
R/W
RESERVED
PRESET 6
PRESET 7
0x248-0x24B
0xC0000000
R/W
NCO Frequency (Preset 7)
0x24C-0x24D
0x0000
R/W
NCO Phase (Preset 7)
0x24E
0xFF
R/W
DDC Delay (Preset 7)
0x24F-0x251
0x00
R/W
RESERVED
0x252-0x27F
Undefined
R
RESERVED
0x0280-0x7FFF
Undefined
R
RESERVED
Reserved
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
49
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1 Register Descriptions
7.6.1.1 Standard SPI-3.0 (0x000 to 0x00F)
Table 34. Standard SPI-3.0 Registers
Address
Reset
Acronym
Register Name
0x000
0x3C
CFGA
Configuration A Register
Section
Go
0x001
0x00
CFGB
Configuration B Register
Go
0x002
0x00
DEVCFG
Device Configuration Register
Go
0x003
0x03
CHIP_TYPE
Chip Type Register
Go
0x004-0x005
0x0000
RESERVED
RESERVED
Go
0x006
0x03
CHIP_VERSION
Chip Version Register
Go
0x007-0x00B
Undefined
RESERVED
RESERVED
0x00C-0x00D
0x0451
VENDOR_ID
Vendor Identification Register
0x00E-0x00F
Undefined
RESERVED
RESERVED
Go
7.6.1.1.1 Configuration A Register (address = 0x000) [reset = 0x3C]
All writes to this register must be a palindrome (for example: bits [3:0] are a mirror image of bits [7:4]). If the data
is not a palindrome, the entire write is ignored.
Figure 37. Configuration A Register (CFGA)
7
SWRST
R/W-0
6
RESERVED
R/W-0
5
ADDR_ASC
R/W-1
4
RESERVED
R/W-1
3
RESERVED
R/W-1
2
ADDR_ASC
R/W-1
1
RESERVED
R/W-0
0
SWRST
R/W-0
Table 35. CFGA Field Descriptions
Bit
Field
Type
Reset
Description
7
SWRST
R/W
0
Setting this bit causes all registers to be reset to their default
state. This bit is self-clearing.
6
RESERVED
R/W
0
5
ADDR_ASC
R/W
1
This bit is NOT reset by a soft reset (SWRST)
0 : descend – decrement address while streaming (address
wraps from 0x0000 to 0x7FFF)
1 : ascend – increment address while streaming (address wraps
from 0x7FFF to 0x0000) (default)
4
RESERVED
R/W
1
Always returns 1
3
RESERVED
R/W
2
ADDR_ASC
R/W
1
RESERVED
R/W
1100
Palindrome bits
bit 3 = bit 4, bit 2 = bit 5, bit 1 = bit 6, bit 0 = bit 7
0
SWRST
R/W
7.6.1.1.2 Configuration B Register (address = 0x001) [reset = 0x00]
Figure 38. Configuration B Register (CFGB)
7
6
5
4
3
2
1
0
RESERVED
R - 0x00h
Table 36. CFGB Field Descriptions
50
Bit
Field
Type
Reset
7:0
RESERVED
R
0000 0000
Description
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.1.3 Device Configuration Register (address = 0x002) [reset = 0x00]
Figure 39. Device Configuration Register (DEVCFG)
7
6
5
4
3
2
1
RESERVED
R/W-000000
0
MODE
R/W-00
Table 37. DEVCFG Field Descriptions
Bit
Field
Type
Reset
7-2
RESERVED
R/W
0000 00
1-0
MODE
R/W
00
Description
SPI 3.0 specification has 1 as low power functional mode and 2
as low power fast resume. This chip does not support these
modes.
0: Normal Operation – full power and full performance (default)
1: Normal Operation – full power and full performance (default)
2: Power Down – Everything powered down
3: Power Down – Everything powered down
7.6.1.1.4 Chip Type Register (address = 0x003) [reset = 0x03]
Figure 40. Chip Type Register (CHIP_TYPE)
7
6
5
4
3
2
RESERVED
R-0000
1
0
CHIP_TYPE
R-0011
Table 38. CHIP_TYPE Field Descriptions
Bit
Field
Type
Reset
7-4
RESERVED
R
0000
3-0
CHIP_TYPE
R
0011
Description
Always returns 0x3, indicating that the part is a high speed ADC.
7.6.1.1.5 Chip Version Register (address = 0x006) [reset = 0x03]
Figure 41. Chip Version Register (CHIP_VERSION)
7
6
5
4
3
CHIP_VERSION
R-0000 0011
2
1
0
Table 39. CHIP_VERSION Field Descriptions
Bit
Field
Type
Reset
7-0
CHIP_VERSION
R
0000 0011 Chip version, returns 0x03
Description
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
51
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.1.6 Vendor Identification Register (address = 0x00C to 0x00D) [reset = 0x0451]
Figure 42. Vendor Identification Register (VENDOR_ID)
15
14
13
12
11
10
9
8
3
2
1
0
VENDOR_ID
R-0x04h
7
6
5
4
VENDOR_ID
R-0x51h
Table 40. VENDOR_ID Field Descriptions
Bit
15-0
Field
Type
Reset
Description
VENDOR_ID
R
0x0451h
Always returns 0x0451 (TI Vendor ID)
7.6.1.2 User SPI Configuration (0x010 to 0x01F)
Table 41. User SPI Configuration Registers
Address
Reset
Acronym
Register Name
0x010
0x00
USR0
User SPI Configuration Register
Section
0x011-0x01F
Undefined
RESERVED
RESERVED
Go
7.6.1.2.1 User SPI Configuration Register (address = 0x010) [reset = 0x00]
Figure 43. User SPI Configuration Register (USR0)
7
6
5
4
RESERVED
R/W-0000 000
3
2
1
0
ADDR_STATIC
R/W-0
Table 42. USR0 Field Descriptions
Bit
Field
Type
Reset
7-1
RESERVED
R/W
0000 000
ADDR_STATIC
R/W
0
0
52
Description
0 : Use ADDR_ASC bit to define what happens to address
during streaming (default).
1 : Address stays static throughout streaming operation. Useful
for reading/writing calibration vector information at
CAL_VECTOR register.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.3 General Analog, Bias, Band Gap, and Track and Hold (0x020 to 0x02F)
Table 43. General Analog, Bias, Band Gap, and Track and Hold Registers
Address
Reset
Acronym
Register Name
0x020
0x9D
RESERVED
RESERVED
Section
0x021
0x00
POR
Power-On Reset Register
Go
0x022
0x40
IO_GAIN_0
I/O Gain 0 Register
Go
0x023
0x00
IO_GAIN_1
I/O Gain 1 Register
Go
0x024
0x00
RESERVED
RESERVED
0x025
0x40
IO_OFFSET_0
I/O Offset 0 Register
Go
0x026
0x00
IO_OFFSET_1
I/O Offset 1 Register
Go
0x027
0x06
RESERVED
RESERVED
0x028
0xBA
RESERVED
RESERVED
0x029
0xD4
RESERVED
RESERVED
0x02A
0xAA
RESERVED
RESERVED
0x02B-0x02F
Undefined
RESERVED
RESERVED
7.6.1.3.1 Power-On Reset Register (address = 0x021) [reset = 0x00]
Figure 44. Power-On Reset Register (POR)
7
6
5
4
RESERVED
R/W-0000 000
3
2
1
0
SPI_RES
R/W-0
Table 44. POR Field Descriptions
Bit
Field
Type
Reset
7-1
RESERVED
R/W
0000 000
SPI_RES
R/W
0
0
Description
Reset all digital. Emulates a power on reset (not self-clearing).
Write a 0 and then write a 1 to emulate a reset. Transition from
0—>1 initiates reset.
Default: 0
7.6.1.3.2 I/O Gain 0 Register (address = 0x022) [reset = 0x40]
Figure 45. I/O Gain 0 Register (IO_GAIN_0)
7
RESERVED
R/W-0
6
GAIN_FS[14]
R/W-1
5
GAIN_FS[13]
R/W-0
4
GAIN_FS[12]
R/W-0
3
GAIN_FS[11]
R/W-0
2
GAIN_FS[10]
R/W-0
1
GAIN_FS[9]
R/W-0
0
GAIN_FS[8]
R/W-0
Table 45. IO_GAIN_0 Field Descriptions
Bit
7
6-0
Field
Type
Reset
RESERVED
R/W
0
GAIN_FS[14:8]
R/W
100 0000
Description
MSB Bits for GAIN_FS[14:0]. (See the IO_GAIN_1 description in
General Analog, Bias, Band Gap, and Track and Hold (0x020 to
0x02F))
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
53
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.3.3 IO_GAIN_1 Register (address = 0x023) [reset = 0x00]
Figure 46. IO_GAIN_1 Register (IO_GAIN_1)
7
GAIN_FS[7]
R/W-0
6
GAIN_FS[6]
R/W-0
5
GAIN_FS[5]
R/W-0
4
GAIN_FS[4]
R/W-0
3
GAIN_FS[3]
R/W-0
2
GAIN_FS[2]
R/W-0
1
GAIN_FS[1]
R/W-0
0
GAIN_FS[0]
R/W-0
Table 46. IO_GAIN_1 Field Descriptions
Bit
Field
Type
Reset
7-0
GAIN_FS[7:0]
R/W
0000 0000 LSB bits for GAIN_FS[14:0]
GAIN_FS[14:0] Value
0x0000 500 mVp-p
0x4000 725 mVp-p (default)
0x7FFF 950 mVp-p
Description
7.6.1.3.4 I/O Offset 0 Register (address = 0x025) [reset = 0x40]
Figure 47. I/O Offset 0 Register (IO_OFFSET_0)
7
RESERVED
R/W-0
6
OFFSET_FS[1
4]
R/W-1
5
OFFSET_FS[1
3]
R/W-0
4
OFFSET_FS[1
2]
R/W-0
3
OFFSET_FS[1
1]
R/W-0
2
OFFSET_FS[1
0]
R/W-0
1
0
OFFSET_FS[9] OFFSET_FS[8]
R/W-0
R/W-0
Table 47. IO_OFFSET_0 Field Descriptions
Bit
7
6-0
Field
Type
Reset
RESERVED
R/W
0
OFFSET_FS[14:8]
R/W
100 0000
Description
MSB Bits for OFFSET_FS[14:0].
The ADC offset adjust feature has no effect when Background
Calibration Mode is enabled. (See IO_OFFSET_1 description in
the General Analog, Bias, Band Gap, and Track and Hold
(0x020 to 0x02F) section).
7.6.1.3.5 I/O Offset 1 Register (address = 0x026) [reset = 0x00]
Figure 48. I/O Offset 1 Register (IO_OFFSET_1)
7
6
5
4
3
2
1
0
OFFSET_FS[7] OFFSET_FS[6] OFFSET_FS[5] OFFSET_FS[4] OFFSET_FS[3] OFFSET_FS[2] OFFSET_FS[1] OFFSET_FS[0]
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
Table 48. IO_OFFSET_1 Field Descriptions
54
Bit
Field
Type
Reset
Description
7-0
OFFSET_FS[7:0]
R/W
0000 0000 LSB bits for OFFSET_FS[14:0]. OFFSET_FS[14:0] adjusts the
offset of the entire ADC (all banks are impacted).
OFFSET_FS[14:0] Value
0x0000 –28-mV offset
0x4000 no offset (default)
0x7FFF 28-mV offset
The ADC offset adjust feature has no effect when Background
Calibration Mode is enabled.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.4 Clock (0x030 to 0x03F)
Table 49. Clock Registers
Address
Reset
Acronym
Register Name
0x030
0xC0
CLKGEN_0
Clock Generator Control 0 Register
Section
Go
0x031
0x07
CLKGEN_1
Clock Generator Status Register
Go
0x032
0x80
CLKGEN_2
Clock Generator Control 2 Register
Go
0x033
0xC3
ANA_MISC
Analog Miscellaneous Register
Go
0x034
0x2F
IN_CL_EN
Clamp Enable Register
Go
0x035
0xDF
RESERVED
RESERVED
0x036
0x00
RESERVED
RESERVED
0x037
0x45
RESERVED
RESERVED
0x038-0x03F
Undefined
RESERVED
RESERVED
7.6.1.4.1 Clock Generator Control 0 Register (address = 0x030) [reset = 0xC0]
Figure 49. Clock Generator Control 0 Register (CLKGEN_0)
7
SysRef_Rcvr_E
n
R/W-1
6
SysRef_Pr_En
5
SysRefDetClr
R/W-1
R/W-0
4
Clear Dirty
Capture
R/W-0
3
RESERVED
R/W-0
2
1
0
DC_LVPECL_C DC_LVPECL_S DC_LVPECL_S
LK_en
YSREF_en
YNC_en
R/W-0
R/W-0
R/W-0
Table 50. CLKGEN_0 Field Descriptions
Bit
Field
Type
Reset
Description
7
SysRef_Rcvr_En
R/W
1
Default: 1
0 : SYSREF receiver is disabled.
1 : SYSREF receiver is enabled (default)
6
SysRef_Pr_En
R/W
1
To power down the SYSREF receiver, clear this bit first, then
clear SysRef_Rcvr_En. To power up the SYSREF receiver, set
SysRef_Rcvr_En first, then set this bit.
Default: 1
0 : SYSREF Processor is disabled.
1 : SYSREF Processor is enabled (default)
5
SysRefDetClr
R/W
0
Default: 0
Write a 1 and then a 0 to clear the SysRefDet status bit.
4
Clear Dirty Capture
R/W
0
Default: 0
Write a 1 and then a 0 to clear the DC status bit.
3
RESERVED
R/W
0
Default: 0
2
DC_LVPECL_CLK_en
R/W
0
Default: 0
Set this bit if DEVCLK is a DC-coupled LVPECL signal through
a 50-Ω resistor.
1
DC_LVPECL_SYSREF_en
R/W
0
Default: 0
Set this bit if SYSREF is a DC-coupled LVPECL signal through
a 50-Ω resistor.
0
DC_LVPECL_SYNC_en
R/W
0
Default: 0
Set this bit if SYNC~ is a DC-coupled LVPECL signal through a
50-Ω resistor.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
55
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.4.2 Clock Generator Status Register (address = 0x031) [reset = 0x07]
Figure 50. Clock Generator Status Register (CLKGEN_1)
7
SysRefDet
R-0
6
Dirty Capture
R-0
5
4
3
2
1
0
RESERVED
R-00 0111
Table 51. CLKGEN_1 Field Descriptions
Bit
Field
Type
Reset
Description
7
SysRefDet
R
0
When high, indicates that a SYSREF rising edge was detected.
To clear this bit, write SysRefDetClr to 1 and then back to 0.
6
Dirty Capture
R
0
When high, indicates that a SYSREF rising edge occurred very
close to the device clock edge, and setup or hold is not ensured
(dirty capture). To clear this bit, write CDC to1 and then back to
0.
NOTE: When sweeping the timing on SYSREF, it may jump
across the clock edge without triggering this bit. The
REALIGNED status bit must be used to detect this (see the
JESD_STATUS register description in Digital Down Converter
and JESD204B (0x200-0x27F))
5-0
RESERVED
R
00 0111
Reserved register. Always returns 000111b
7.6.1.4.3 Clock Generator Control 2 Register (address = 0x032) [reset = 0x80]
Figure 51. Clock Generator Control 2 Register (CLKGEN_2)
7
6
5
4
3
2
RESERVED
R/W-1000
1
0
RDEL
R/W-0000
Table 52. CLKGEN_2 Field Descriptions
56
Bit
Field
Type
Reset
Description
7-4
RESERVED
R/W
1000
Default: 1000b
3-0
RDEL
R/W
0000
Adjusts the delay of the SYSREF input signal with respect to
DEVCLK.
Each step delays SYSREF by 20 ps (nominal)
Default: 0
Range: 0 to 15 decimal
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.4.4 Analog Miscellaneous Register (address = 0x033) [reset = 0xC3]
Figure 52. Analog Miscellaneous Register (ANA_MISC)
7
6
5
RESERVED
R/W-1100 0
4
3
2
SYNC_DIFF_PD
R/W-0
1
0
RESERVED
R/W-11
Table 53. ANA_MISC Field Descriptions
Bit
Field
Type
Reset
7-3
RESERVED
R/W
1100 0
SYNC_DIFF_PD
R/W
0
Set this bit to power down the differential SYNC~± inputs for the
JESD204B interface.
The receiver must be powered up to support the differential
SYNC~.
Default: 0b
RESERVED
R/W
11
Default: 11b
2
1-0
Description
7.6.1.4.5 Input Clamp Enable Register (address = 0x034) [reset = 0x2F]
Figure 53. Input Clamp Enable Register (IN_CL_EN)
7
6
RESERVED
R/W-00
5
INPUT_CLAMP_EN
R/W-1
4
3
2
RESERVED
R/W-0 1111
1
0
Table 54. IN_CL_EN Field Descriptions
Bit
Field
Type
Reset
Description
7-6
RESERVED
R/W
00
Default: 00b
INPUT_CLAMP_EN
R/W
1
Set this bit to enable the analog input active clamping circuit.
Enabled by default.
Default: 1b
RESERVED
R/W
0 1111
Default: 01111b
5
4-0
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
57
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.5 Serializer (0x040 to 0x04F)
Table 55. Serializer Registers
Address
Reset
Acronym
Register Name
0x040
0x04
SER_CFG
Serializer Configuration Register
Section
0x041-0x04F
Undefined
RESERVED
RESERVED
Go
7.6.1.5.1 Serializer Configuration Register (address = 0x040) [reset = 0x04]
Figure 54. Serializer configuration Register (SER_CFG)
7
6
5
4
3
RESERVED
R/W-0000
2
1
SERIALIZER PRE-EMPHASIS
R/W-0100
0
Table 56. SER_CFG Field Descriptions
58
Bit
Field
Type
Reset
7-4
RESERVED
R/W
0000
3-0
SERIALIZER PRE-EMPHASIS
R/W
0100
Description
Control bits for the pre-emphasis strength of the serializer output
driver. Pre-emphasis is required to compensate the low pass
behavior of the PCB trace.
Default: 4d
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.6 ADC Calibration (0x050 to 0x1FF)
Table 57. ADC Calibration Registers
Address
Reset
Acronym
Register Name
0x050
0x06
CAL_CFG0
Calibration Configuration 0 Register
Section
Go
0x051
0xF4
CAL_CFG1
Calibration Configuration 1 Register
Go
0x052
0x00
RESERVED
RESERVED
0x053
0x5C
RESERVED
RESERVED
0x054
0x1C
RESERVED
RESERVED
0x055
0x92
RESERVED
RESERVED
0x056
0x20
RESERVED
RESERVED
0x057
0x10
CAL_BACK
Calibration Background Control Register
Go
0x058
0x00
ADC_PAT_OVR_EN
ADC Pattern and Over-Range Enable
Register
Go
0x059
0x00
RESERVED
RESERVED
0x05A
0x00
CAL_VECTOR
Calibration Vectors Register
Go
0x05B
Undefined
CAL_STAT
Calibration Status Register
Go
0x05C
0x00
RESERVED
RESERVED
0x05D-0x05E
Undefined
RESERVED
RESERVED
0x05F
0x00
RESERVED
RESERVED
0x060
Undefined
RESERVED
RESERVED
0x061
Undefined
RESERVED
RESERVED
0x062
Undefined
RESERVED
RESERVED
0x063
Undefined
RESERVED
RESERVED
0x064
Undefined
RESERVED
RESERVED
0x065
Undefined
RESERVED
RESERVED
0x066
0x02
T_CAL
Timing Calibration Register
0x067
0x01
RESERVED
RESERVED
0x068
Undefined
RESERVED
RESERVED
0x069
Undefined
RESERVED
RESERVED
0x06A
0x00
RESERVED
RESERVED
0x06B
0x20
RESERVED
RESERVED
0x06C-0x1FF
Undefined
RESERVED
RESERVED
Go
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
59
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.6.1 Calibration Configuration 0 Register (address = 0x050) [reset = 0x06]
Figure 55. Calibration Configuration 0 Register (CAL_CFG0)
7
6
RESERVED
R/W-00
5
4
CALIBRATION_READ_WRITE_EN
R/W-0
R/W-0
3
CAL_SFT
R/W-0
2
1
RESERVED
R/W-110
0
Table 58. CAL_CFG0 Field Descriptions
(1)
Bit
Field
Type
Reset
7-5
RESERVED
R/W
000
Description
4
CALIBRATION_READ_WRITE_EN
R/W
0
Enables the scan register to read or write calibration vectors at
register 0x05A.
Default: 0
3
CAL_SFT (1)
R/W
0
Software calibration bit. Set bit to initiate foreground calibration.
This bit is self-clearing.
This bit resets the calibration state machine. Most calibration
SPI registers are not synchronized to the calibration clock.
Changing them may corrupt the calibration state machine.
Always set CAL_SFT AFTER making any changes to the
calibration registers.
2-0
RESERVED
R/W
110
Default: 110
IMPORTANT NOTE: Setting CAL_SFT can glitch internal state machines. The JESD_EN bit must be cleared and then set after setting
CAL_SFT.
7.6.1.6.2 Calibration Configuration 1 Register (address = 0x051) [reset = 0xF4]
Figure 56. Calibration Configuration 1 Register (CAL_CFG1)
7
RESERVED
R/W-1
6
5
LOW_SIG_EN
R/W-111
4
3
2
1
0
RESERVED
R/W-0100
Table 59. CAL_CFG1 Field Descriptions
Bit
7
60
Field
Type
Reset
RESERVED
R/W
1
6-4
LOW_SIG_EN
R/W
111
3-0
RESERVED
R/W
0100
Description
Controls signal range optimization for calibration processes.
111: Calibration is optimized for lower amplitude input signals (<
–10dBFS).
000: Calibration is optimized for large (-1dBFS) input
signals.
Default: 111 but recommend 000 for large input signals.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.6.3 Calibration Background Control Register (address = 0x057) [reset = 0x10]
Figure 57. Calibration Background Control Register (CAL_BACK)
7
6
5
4
3
2
1
CAL_CONT
R/W-0
RESERVED
R/W-0001 00
0
CAL_BCK
R/W-0
Table 60. CAL_BACK Field Descriptions
Bit
Field
Type
Reset
Description
7-2
RESERVED
R/W
0001 00
Set to 0001 00b
1
CAL_CONT
R/W
0
CAL_CONT is the only calibration register bit that can be
modified while background calibration is ongoing. This bit must
be set to 0 before modifying any of the other bits.
0 : Pause or stop background calibration sequence.
1 : Start background calibration sequence.
0
CAL_BCK
R/W
0
Background calibration mode enabled. When pausing
background calibration leave this bit set, only change
CAL_CONT to 0.
If CAL_BCK is set to 0 after background calibration has been
operation the calibration processes may stop in an incomplete
condition. Set CAL_SFT to perform a foreground calibration
7.6.1.6.4 ADC Pattern and Over-Range Enable Register (address = 0x058) [reset = 0x00]
Figure 58. ADC Pattern and Over-Range Enable Register (ADC_PAT_OVR_EN)
7
6
5
RESERVED
R/W-0000 0
4
3
2
ADC_PAT_EN
R/W-0
1
OR_EN
R/W-0
0
RESERVED
R/W-0
1
0
Table 61. ADC_PAT_OVR_EN Field Descriptions
Bit
Field
Type
Reset
Description
7-3
RESERVED
R/W
0000 0
Set to 00000b
2
ADC_PAT_EN
R/W
0
Enable ADC test pattern
1
OR_EN
R/W
0
Enable over-range output
0
RESERVED
R/W
0
Set to 0
7.6.1.6.5 Calibration Vectors Register (address = 0x05A) [reset = 0x00]
Figure 59. Calibration Vectors Register (CAL_VECTOR)
7
6
5
4
3
2
CAL_DATA
R/W-0000 0000
Table 62. CAL_VECTOR Field Descriptions
Bit
Field
Type
Reset
7-0
CAL_DATA
R/W
0000 0000 Repeated reads of this register outputs all the calibration register
values for analysis if the CALIBRATION_READ_WRITE_EN bit
is set.
Repeated writes of this register inputs all the calibration register
values for configuration if the CAL_RD_EN bit is set.
Description
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
61
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.6.6 Calibration Status Register (address = 0x05B) [reset = undefined]
Figure 60. Calibration Status Register (CAL_STAT)
7
6
5
4
RESERVED
R-0000 10
3
2
1
CAL_CONT_OFF
R-X
0
FIRST_CAL_DONE
R-X
Table 63. CAL_STAT Field Descriptions
Bit
Field
Type
Reset
7-2
RESERVED
R
0000
10XX
Description
1
CAL_CONT_OFF
R
X
After clearing CAL_CONT, calibration does not stop
immediately. Use this register to confirm it has stopped before
changing calibration settings.
0: Indicates calibration is running (foreground or background)
1: Indicates that calibration is finished or stopped because
CAL_CONT = 0
0
FIRST_CAL_DONE
R
X
Indicates first calibration sequence has been done and ADC is
operational.
7.6.1.6.7 Timing Calibration Register (address = 0x066) [reset = 0x02]
Figure 61. Timing Calibration Register (T_CAL)
7
6
5
4
RESERVED
R/W-0000 001
3
2
1
0
T_AUTO
R/W-0
Table 64. CAL_STAT Field Descriptions
Bit
Field
Type
Reset
Description
7-1
RESERVED
R/W
0000 001
Set to 0000001b
T_AUTO
R/W
0
Set to enable automatic timing optimization. Timing calibration
will occur once CAL_SFT is set.
0
62
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.7 Digital Down Converter and JESD204B (0x200-0x27F)
Table 65. Digital Down Converter and JESD204B Registers
Address
Reset
Acronym
Register Name
0x200
0x10
DDC_CTRL1
Digital Down-Converter (DDC) Control
Section
Go
0x201
0x0F
JESD_CTRL1
JESD204B Control 1
Go
0x202
0x00
JESD_CTRL2
JESD204B Control 2
Go
0x203
0x00
JESD_DID
JESD204B Device ID (DID)
Go
0x204
0x00
JESD_CTRL3
JESD204B Control 3
Go
0x205
Undefined
JESD_STATUS
JESD204B and System Status Register
Go
0x206
0xF2
OVR_T0
Overrange Threshold 0
Go
0x207
0xAB
OVR_T1
Overrange Threshold 1
Go
0x208
0x00
OVR_N
Overrange Period
Go
0x209-0x20B
0x00
RESERVED
RESERVED
0x20C
0x00
NCO_MODE
DDC Configuration Preset Mode
Go
0x20D
0x00
NCO_SEL
DDC Configuration Preset Select
Go
0x20E-0x20F
0x0000
NCO_RDIV
Rational NCO Reference Divisor
Go
0x210-0x213
0xC0000000
NCO_FREQ0
NCO Frequency (Preset 0)
Go
0x214-0x215
0x0000
NCO_PHASE0
NCO Phase (Preset 0)
Go
0x216
0xFF
DDC_DLY0
DDC Delay (Preset 0)
Go
0x217
0x00
RESERVED
RESERVED
NCO_FREQ1
NCO Frequency (Preset 1)
Go
NCO_PHASE1
NCO Phase (Preset 1)
Go
Go
0x218-0x21B
0xC0000000
0x21C-0x21D
0x0000
0x21E
0xFF
DDC_DLY1
DDC Delay (Preset 1)
0x21F
0x00
RESERVED
RESERVED
0x220-0x223
0xC0000000
NCO_FREQ2
NCO Frequency (Preset 2)
Go
0x224-0x225
0x0000
NCO_PHASE2
NCO Phase (Preset 2)
Go
0x226
0xFF
DDC_DLY2
DDC Delay (Preset 2)
Go
0x227
0x00
RESERVED
RESERVED
NCO_FREQ3
NCO Frequency (Preset 3)
Go
NCO_PHASE3
NCO Phase (Preset 3)
Go
Go
0x228-0x22B
0xC0000000
0x22C-0x22D
0x0000
0x22E
0xFF
DDC_DLY3
DDC Delay (Preset 3)
0x22F
0x00
RESERVED
RESERVED
0x230-0x233
0xC0000000
NCO_FREQ4
NCO Frequency (Preset 4)
Go
0x234-0x235
0x0000
NCO_PHASE4
NCO Phase (Preset 4)
Go
0x236
0xFF
DDC_DLY4
DDC Delay (Preset 4)
Go
0x237
0x00
RESERVED
RESERVED
NCO_FREQ5
NCO Frequency (Preset 5)
Go
NCO_PHASE5
NCO Phase (Preset 5)
Go
Go
0x238-0x23B
0xC0000000
0x23C-0x23D
0x0000
0x23E
0xFF
DDC_DLY5
DDC Delay (Preset 5)
0x23F
0x00
RESERVED
RESERVED
0x240-0x243
0xC0000000
NCO_FREQ6
NCO Frequency (Preset 6)
Go
0x244-0x245
0x0000
NCO_PHASE6
NCO Phase (Preset 6)
Go
0x246
0xFF
DDC_DLY6
DDC Delay (Preset 6)
Go
0x247
0x00
RESERVED
RESERVED
NCO_FREQ7
NCO Frequency (Preset 7)
Go
NCO_PHASE7
NCO Phase (Preset 7)
Go
Go
0x248-0x24B
0xC0000000
0x24C-0x24D
0x0000
0x24E
0xFF
DDC_DLY7
DDC Delay (Preset 7)
0x24F-0x251
0x00
RESERVED
RESERVED
0x252-0x27F
Undefined
RESERVED
RESERVED
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
63
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.7.1 Digital Down-Converter (DDC) Control Register (address = 0x200) [reset = 0x10]
Figure 62. Digital Down-Converter (DDC) Control Register (DDC_CTRL1)
7
6
RESERVED
5
4
DDC GAIN
BOOST
R/W-1
R/W-000
3
2
1
0
DMODE
R/W-0000
Table 66. DDC_CTRL1 Field Descriptions
Bit
Field
Type
Reset
7-5
RESERVED
R/W
000
DDC GAIN BOOST
R/W
1
0 : Final filter has 0-dB gain (recommended when NCO is set
near DC).
1 : Final filter has 6.02-dB gain (default)
DMODE (1)
R/W
0000
0 : decimate-by-4 (default)
1 : Reserved
2 : decimate-by-4
3 : decimate-by-8
4 : decimate-by-10
5 : decimate-by-16
6 : decimate-by-20
7 : decimate-by-32
8..15 : RESERVED
4
3-0
(1)
Description
The DMODE setting must only be changed when JESD_EN is 0.
7.6.1.7.2 JESD204B Control 1 Register (address = 0x201) [reset = 0x0F]
Figure 63. JESD204B Control 1 Register (JESD_CTRL1)
7
SCR
R/W-0
6
5
4
K_Minus_1
R/W-000 11
3
2
1
DDR
R/W-1
0
JESD_EN
R/W-1
Table 67. JESD_CTRL1 Field Descriptions
Bit
Field
Type
Reset
Description
7
SCR
R/W
0
0 : Scrambler disabled (default)
1 : Scrambler enabled
K_Minus_1
R/W
000 11
K is the number of frames per multiframe, and K – 1 is
programmed here.
Default: K = 4, K_Minus_1 = 3.
Depending on the decimation (D) and serial rate (DDR), there
are constraints on the legal values of K.
1
DDR
R/W
1
0 : SDR serial rate (ƒ(BIT) = ƒS)
1 : DDR serial rate (ƒ(BIT) = 2ƒS) (default)
0
JESD_EN (1)
R/W
1
0 : Block disabled
1 : Normal operation (default)
6-2
(1)
64
Before altering any parameters in the JESD_CTRL1 register, you must set JESD_EN to 0. When JESD_EN is 0, the block is held in
reset and the serializers are powered down. The clocks are gated off to save power.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.7.3 JESD204B Control 2 Register (address = 0x202) [reset = 0x00]
Figure 64. JESD204B Control 2 Register (JESD_CTRL2)
7
P54
R/W-0
6
SYNC_DIFFSEL
R/W-0
5
4
RESERVED
R/W-00
3
2
1
JESD204B_TEST
R/W-0000
0
Table 68. JESD_CTRL2 Field Descriptions
Bit
Field
Type
Reset
Description
7
P54
R/W
0
0 : Disable 5/4 PLL. Serial bit rate is 1x or 2x based on DDR
parameter.
1 : Enable 5/4 PLL. Serial bit rate is 1.25x or 2.5x based on
DDR parameter.
6
SYNC_DIFFSEL
R/W
0
0 : Use SYNC_SE_N input for SYNC_N function
1 : Use SYNC_DIFF_N input for SYNC_N function
R/W
00
Set to 00b
R/W
0000
See
0 : Test mode disabled. Normal operation (default)
1 : PRBS7 test mode
2 : PRBS15 test mode
3 : PRBS23 test mode
4 : Ramp test mode
5 : Short and long transport layer test mode
6 : D21.5 test mode
7 : K28.5 test mode
8 : Repeated ILA test mode
9 : Modified RPAT test mode
10: Serial outputs held low
11: Serial outputs held high
12 through 15 : RESERVED
5-4
RESERVED
3-0
(1)
JESD204B_TEST
(1)
The JESD_CTRL2 register must only be changed when JESD_EN is 0.
7.6.1.7.4 JESD204B Device ID (DID) Register (address = 0x203) [reset = 0x00]
Figure 65. JESD204B Device ID (DID) Register (JESD_DID)
7
6
5
4
3
2
1
0
JESD_DID
R/W-0000 0000
Table 69. JESD_DID Field Descriptions
Bit
7-0
(1)
Field
JESD_DID
(1)
Type
Reset
Description
R/W
0000 0000 Specifies the DID value that is transmitted during the second
multiframe of the JESD204B ILA.
The DID setting must only be changed when JESD_EN is 0.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
65
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.7.5 JESD204B Control 3 Register (address = 0x204) [reset = 0x00]
Figure 66. JESD204B Control 3 Register (JESD_CTRL3)
7
6
5
4
3
2
1
0
RESERVED
R/W-0000 00
FCHAR
R/W-00
Table 70. JESD_CTRL3 Field Descriptions
(1)
Bit
Field
Type
Reset
7-2
RESERVED
R/W
0000 00
1-0
FCHAR (1)
R/W
00
Description
Specify which comma character is used to denote end-of-frame.
This character is transmitted opportunistically according to
JESD204B Section 5.3.3.4.
When using a JESD204B receiver, always use FCHAR=0.
When using a general purpose 8-b or 10-b receiver, the K28.7
character can cause issues. When K28.7 is combined with
certain data characters, a false, misaligned comma character
can result, and some receivers realign to the false comma. To
avoid this, program FCHAR to 1 or 2.
0 : Use K28.7 (default) (JESD204B compliant)
1 : Use K28.1 (not JESD204B compliant)
2 : Use K28.5 (not JESD204B compliant)
3 : Reserved
The JESD_CTRL3 register must only be changed when JESD_EN is 0.
7.6.1.7.6 JESD204B and System Status Register (address = 0x205) [reset = Undefined]
See the JESD204B Synchronization Features section for more details.
Figure 67. JESD204B and System Status Register (JESD_STATUS)
7
RESERVED
R/W-0
6
LINK_UP
R/W-0
5
SYNC_STATUS
R/W-X
4
REALIGNED
R/W-X
3
ALIGNED
R/W-0
2
PLL_LOCKED
R/W-0
1
0
RESERVED
R/W-00
Table 71. JESD_STATUS Field Descriptions
Bit
Field
Type
Reset
Description
7
RESERVED
R/W
0
Always returns 0
6
LINK_UP
R/W
0
When set, indicates that the JESD204B link is in the DATA_ENC
state.
5
SYNC_STATUS
R/W
X
Returns the state of the JESD204B SYNC~ signal (SYNC_SE_N
or SYNC_DIFF_N).
0 : SYNC~ asserted
1 : SYNC~ deasserted
4
REALIGNED
R/W
X
When high, indicates that the div8 clock, frame clock, or
multiframe clock phase was realigned by SYSREF.
Writing a 1 to this bit clears it.
3
ALIGNED
R/W
0
When high, indicates that the multiframe clock phase has been
established by SYSREF. The first SYSREF event after enabling
the JESD204B encoder will set this bit.
Writing a 1 to this bit clears it.
2
PLL_LOCKED
R/W
0
When high, indicates that the PLL is locked.
RESERVED
R/W
0
Always returns 0
1-0
66
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.7.7 Overrange Threshold 0 Register (address = 0x206) [reset = 0xF2]
Figure 68. Overrange Threshold 0 Register (OVR_T0)
7
6
5
4
3
2
1
0
OVR_T0
R/W-1111 0010
Table 72. OVR_T0 Field Descriptions
Bit
Field
Type
Reset
7-0
OVR_T0
R/W
1111 0010 Over-range threshold 0. This parameter defines the absolute
sample level that causes control bit 0 to be set. Control bit 0 is
attached to the DDC I output samples. The detection level in
dBFS (peak) is
20log10(OVR_T0 / 256)
Default: 0xF2 = 242 → –0.5 dBFS
Description
7.6.1.7.8 Overrange Threshold 1 Register (address = 0x207) [reset = 0xAB]
Figure 69. Overrange Threshold 1 Register (OVR_T1)
7
6
5
4
3
2
1
0
OVR_T1
R/W-1010 1011
Table 73. OVR_T1 Field Descriptions
Bit
Field
Type
Reset
Description
7-0
OVR_T1
R/W
1010 1011 Overrange threshold 1. This parameter defines the absolute
sample level that causes control bit 1 to be set. Control bit 1 is
attached to the DDC Q output samples. The detection level in
dBFS (peak) is
20log10(OVR_T1 / 256)
Default: 0xAB = 171 → –3.5 dBFS
7.6.1.7.9 Overrange Period Register (address = 0x208) [reset = 0x00]
Figure 70. Overrange Period Register (OVR_N)
7
6
5
RESERVED
R/W-0000 0
4
3
2
1
OVR_N
R/W-000
0
Table 74. OVR_N Field Descriptions
(1)
Bit
Field
Type
Reset
7-3
RESERVED
R/W
0000 0
2-0
OVR_N (1)
R/W
000
Description
This bit adjusts the monitoring period for the OVR[1:0] output
bits. The period is scaled by 2OVR_N. Incrementing this field
doubles the monitoring period.
Changing the OVR_N setting while JESD_EN=1 may cause the phase of the monitoring period to change.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
67
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.7.10 DDC Configuration Preset Mode Register (address = 0x20C) [reset = 0x00]
Figure 71. DDC Configuration Preset Mode Register (NCO_MODE)
7
6
5
4
RESERVED
R/W-0000 000
3
2
1
0
CFG_MODE
R/W-0
Table 75. NCO_MODE Field Descriptions
Bit
Field
Type
Reset
7-1
RESERVED
R/W
0000 000
0
CFG_MODE
R/W
0
Description
The NCO frequency and phase are set by the NCO_FREQx and
NCO_PHASEx registers, where x is the configuration preset (0
through 7). The DDC delay setting is defined by the DDC_DLYx
register.
0 : Use NCO_[2:0] input pins to select the active DDC and NCO
configuration preset.
1 : Use the NCO_SEL register to select the active DDC and
NCO configuration preset.
7.6.1.7.11 DDC Configuration Preset Select Register (address = 0x20D) [reset = 0x00]
Figure 72. DDC Configuration Preset Select Register (NCO_SEL)
7
6
5
RESERVED
R/W-0000 0
4
3
2
1
NCO_SEL
R/W-000
0
Table 76. NCO_SEL Field Descriptions
68
Bit
Field
Type
Reset
7-3
RESERVED
R/W
0000 0
2-0
NCO_SEL
R/W
000
Description
When NCO_MODE = 1, this register is used to select the active
configuration preset.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.7.12 Rational NCO Reference Divisor Register (address = 0x20E to 0x20F) [reset = 0x0000]
Figure 73. Rational NCO Reference Divisor Register (NCO_RDIV)
15
14
13
12
11
10
9
8
3
2
1
0
NCO_RDIV
R/W-0x00h
7
6
5
4
NCO_RDIV
R/W-0x00h
Table 77. NCO_RDIV Field Descriptions
Bit
15-0
Field
Type
Reset
Description
NCO_RDIV
R/W
0x0000h
Sometimes the 32-bit NCO frequency word does not provide the
desired frequency step size and can only approximate the
desired frequency. This results in a frequency error. Use this
register to eliminate the frequency error. Use this equation to
compute the proper value to program:
NCO_RDIV = ƒS / ƒ(STEP) / 128
where
•
•
ƒS is the ADC sample rate
ƒ(STEP) is the desired NCO frequency step size
(10)
For example, if ƒS= 3072 MHz, and ƒ(STEP) = 10 KHz then:
NCO_RDIV = 3072 MHz / 10 KHz / 128 = 2400
(11)
Any combination of ƒS and ƒ(STEP) that results in a fractional
value for NCO_RDIV is not supported. Values of NCO_RDIV
larger than 8192 can degrade the NCO’s SFDR performance
and are not recommended. This register is used for all
configuration presets.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
69
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
7.6.1.7.13 NCO Frequency (Preset x) Register (address = see Table 65) [reset = see Table 65]
Figure 74. NCO Frequency (Preset x) Register (NCO_FREQ_x)
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
NCO_FREQ_x
R/W-0xC0h
23
22
21
20
NCO_FREQ_x
R/W-0x00h
15
14
13
12
NCO_FREQ_x
R/W-0x00h
7
6
5
4
NCO_FREQ_x
R/W-0x00h
Table 78. NCO_FREQ_x Field Descriptions
Bit
31-0
Field
Type
Reset
Description
NCO_FREQ_x
R/W
0xC00000
00h
Changing this register after the JESD204B interface is running
results in non-deterministic NCO phase. If deterministic phase is
required, the JESD204B interface must be re-initialized after
changing this register.
The NCO frequency (ƒ(NCO)) is:
ƒ(NCO) = NCO_FREQ_x × 2–32 × ƒS
where
•
•
ƒS is the sampling frequency of the ADC
NCO_FREQ_x is the integer value of this
register
(12)
This register can be interpreted as signed or unsigned.
Use this equation to determine the value to program:
NCO_FREQ_x = 232 × ƒ(NCO) / ƒS
(13)
If the equation does not result in an integer value, you must
choose an alternate frequency step (ƒ(STEP) ) and program the
NCO_RDIV register. Then use one of the following equations to
compute NCO_FREQ_x:
NCO_FREQ_x = round(232 × ƒ(NCO) / ƒS)
NCO_FREQ_x = round(225 × ƒ(NCO) / ƒ(STEP) /
NCO_RDIV)
70
Submit Documentation Feedback
(14)
(15)
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
7.6.1.7.14 NCO Phase (Preset x) Register (address = see Table 65) [reset = see Table 65]
Figure 75. NCO Phase (Preset) Register (NCO_PHASE_x)
15
14
13
12
11
NCO_PHASE_x
R/W-0x00h
10
9
8
7
6
5
4
2
1
0
3
NCO_PHASE_x
R/W-0x00h
Table 79. NCO_PHASE_x Field Descriptions
Bit
15-0
Field
Type
Reset
Description
NCO_PHASE_x
R/W
0x0000h
This value is MSB-justified into a 32−bit field and then added to
the phase accumulator. The phase (in radians) is
NCO_PHASE_x × 2–16 × 2π
(16)
This register can be interpreted as signed or unsigned.
7.6.1.7.15 DDC Delay (Preset x) Register (address = see Table 65) [reset = see Table 65]
Figure 76. DDC Delay (Preset) Register (DDC_DLY_x)
7
6
5
4
3
2
1
0
DDC_DLY_x
R/W-0xFFh
Table 80. DDC_DLY_x Field Descriptions
Bit
Field
Type
Reset
Description
7-0
DDC_DLY_x
R/W
0xFFh
DDC delay for configuration preset 0
This register provides fine adjustments to the DDC group delay.
The step size is one half of an ADC sample period (t(DEVCLK) /
2). This is equivalent to Equation 17.
tO / (2 × D)
where
•
•
tO is the DDC output sample period
D is the decimation factor
(17)
The legal range for this register is 0 to 2D-1. Illegal values result
in undefined behavior.
Example: When D = 8, the legal register range is 0 to 15. The
step size is tO / 16 and the maximum delay is 15 × tO / 16.
Programming this register to 0xFF (the default value) powers
down and bypasses the fractional delay filter which reduces the
DDC latency by 34 ADC sample periods (as compared to the 0
setting).
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
71
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LM15851 device is a wideband sampling and digital tuning device. The ADC input captures input signals
from DC to greater than 3 GHz. The DDC performs digital-down conversion and programmable decimation
filtering, and outputs complex (15 bit I and 15 bit Q) data. The resulting output data is output on the JESD204B
data interface for capture by the downstream capture or processing device. Most frequency-domain applications
benefit from DDC capability to select the desired frequency band and provide only the necessary bandwidth of
output data, minimizing the required number of data signals.
8.2 Typical Application
8.2.1 RF Sampling Receiver
An RF Sampling Receiver is used to directly sample a signal in the RF frequency range and provide the data for
the captured signal to downstream processing. The wide input bandwidth, high sampling rate, and DDC features
of the LM15851 make it ideally suited for this application.
SPI
Master
Over-Range Logic
FPGA
1:2 Balun
4.7 nF
BPF
L Lanes
ADC
Limiter
Diode
JESD204B
Receiver
SYNC~
SYSREF
DEVCLK
4.7 nF
JESD204B
Clock Generator
Data Processing
and Storage
SYSREF
and FPGA
CLKs
Figure 77. Simplified Schematic
72
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Typical Application (continued)
8.2.1.1 Design Requirements
For this design example, use the parameters listed in Table 81.
Table 81. Design Parameters
DESIGN PARAMETERS
EXAMPLE VALUES
Signal center frequency
2500 MHz
Signal bandwidth
100 MHz
Signal nominal amplitude
–7 dBm
Signal maximum amplitude
6 dBm
Minimum SINAD (in bandwidth of interest)
48 dBc
Minimum SFDR (in bandwidth of interest)
60 dBc
8.2.1.2 Detailed Design Procedure
Use the following steps to design the RF receiver:
• Use the signal-center frequency and signal bandwidth to select an appropriate sampling rate (DEVCLK
frequency) and decimate factor (x / 4 to x / 32).
• Select the sampling rate so that the band of interest is completely within a Nyquist zone.
• Select the sampling rate so that the band of interest is away from any harmonics or interleaving tones.
• Use a frequency planning tool, such as the ADC harmonic calculator (see the Development Support section).
• Select the decimation factor that provides the highest factor possible with an adequate alias-protected output
bandwidth to capture the frequency bandwidth of interest.
• Select other system components to provide the needed signal frequency range and DEVCLK rate.
• See Table 1 for recommended balun components.
• Select bandpass filters and limiter components based on the requirement to attenuate unwanted signals
outside the band of interest (blockers) and to prevent large signals from damaging the ADC inputs. See the
Absolute Maximum Ratings table.
The LMK048xx JESD204B clocking devices can provide the DEVCLK clock and other system clocks for ƒ(DEVCLK)
< 3101 MHz.
For DEVCLK frequencies up to 4 GHz the consider using the LMX2581 and TRF3765 devices as the DEVCLK
source. Use the LMK048xx device to provide the JESD204B clocks. For additional device information, see the
Related Documentation section.
8.2.1.3 Application Curves
The following curve shows an RF signal at 2497.97 MHz captured at a sample rate of 4000 MSPS. Figure 78
shows the spectrum for the output data in decimate-by-32 mode with ƒ(NCO) equal to 2500 MHz. Figure 78 shows
the ability to provide only the spectrum of interest in the decimated output data.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
73
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
0
Magnitude (dBFS)
-20
-40
-60
-80
-100
-120
-62.5 -50 -37.5 -25 -12.5 0 12.5
Frequency (MHz)
ƒS = 4000 MSPS
25
37.5
50
62.5
D001
FIN = 2497.97 MHz at –7 dBFS
ƒ(NCO) = 2500 MHz
Figure 78. Spectrum — Decimate-by-32
8.3 Initialization Set-Up
8.3.1 JESD204B Startup Sequence
The JESD204B interface requires a specific startup and alignment sequence. The general order of that sequence
is listed in the following steps.
1. Power up or reset the LM15851 device.
2. Program JESD_EN = 0 to shut down the link and enable configuration changes.
3. Program DECIMATE, SCRAM_EN, KM1 and DDR to the desired settings.
4. Configure the device calibration settings as desired, and initiate a calibration (set CAL_SFT = 1).
5. Program JESD_EN = 1 to enable the link.
6. Apply at least one SYSREF rising edge to establish the LMFC phase.
7. Assert SYNC~ from the data receiver to initiate link communications.
8. After the JESD204B receiver has established code group synchronization, SYNC~ is de-asserted and the
ILA process begins.
9. Immediately following the end of the ILA sequence normal data output begins.
NOTE
If deterministic latency is not required this step can be omitted.
8.4 Dos and Don'ts
8.4.1 Common Application Pitfalls
Driving the inputs (analog or digital) beyond the power supply rails. For device reliability, an input must not
go more than 150 mV below the ground pins or 150 mV above the supply pins. Exceeding these limits even on a
transient basis can cause faulty, or erratic, operation and can impair device reliability. High-speed digital circuits
exhibiting undershoot that goes more than a volt below ground is common. To control overshoot, the impedance
of high-speed lines must be controlled and these lines must be terminated in the characteristic impedance.
Care must be taken not to overdrive the inputs of the LM15851 device. Such practice can lead to conversion
inaccuracies and even to device damage.
Incorrect analog input common-mode voltage in the DC-coupled mode. As described in the The Analog
Inputs and DC Coupled Input Usage sections, the input common-mode voltage (VCMI) must remain the specified
range as referenced to the VCMO pin, which has a variability with temperature that must also be tracked.
Distortion performance is degraded if the input common mode voltage is outside the specified VCMI range.
74
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Dos and Don'ts (continued)
Using an inadequate amplifier to drive the analog input. Use care when choosing a high frequency amplifier
to drive the LM15851 device because many high-speed amplifiers have higher distortion than the LM15851
device which results in overall system performance degradation.
Driving the clock input with an excessively high level signal. The ADC input clock level must not exceed the
level described in the Recommended Operating Conditions table because the input offset can change if these
levels are exceeded.
Inadequate input clock levels. As described in the Using the Serial Interface section, insufficient input clock
levels can result in poor performance. Excessive input-clock levels can result in the introduction of an input
offset.
Using a clock source with excessive jitter, using an excessively long input clock signal trace, or having
other signals coupled to the input clock signal trace. These pitfalls cause the sampling interval to vary which
causes excessive output noise and a reduction in SNR performance.
Failure to provide adequate heat removal. As described in the Thermal Management section, providing
adequate heat removal is important to ensure device reliability. Adequate heat removal is primarily provided by
properly connecting the thermal pad to the circuit board ground planes. Multiple vias should be arranged in a grid
pattern in the area of the thermal pad. These vias will connect the topside pad to the internal ground planes and
to a copper pour area on the opposite side of the printed circuit board.
9 Power Supply Recommendations
Data-converter-based systems draw sufficient transient current to corrupt their own power supplies if not
adequately bypassed. A 10-µF capacitor must be placed within one inch (2.5 cm) of the device power pins for
each supply voltage. A 0.1-µF capacitor must be placed as close as possible to each supply pin, preferably
within 0.5 cm. Leadless chip capacitors are preferred due to their low-lead inductance.
As is the case with all high-speed converters, the LM15851 device must be assumed to have little power-supply
noise-rejection. Any power supply used for digital circuitry in a system where a large amount of digital power is
consumed must not be used to supply power to the LM15851 device. If not a dedicated supply, the ADC supplies
must be the same supply used for other analog circuitry.
9.1 Supply Voltage
The LM15851 device is specified to operate with nominal supply voltages of 1.9 V (VA19) and 1.2 V (VA12,
VD12). For detailed information regarding the operating voltage minimums and maximums see the
Recommended Operating Conditions table.
During power-up the voltage on all 1.9-V supplies must always be equal to or greater than the voltage on the 1.2V supplies. Similarly, during power-down, the voltage on the 1.2-V supplies must always be lower than or equal
to that of the 1.9-V supplies. In general, supplying all 1.9-V buses from a single regulator, and all 1.2-V buses
from a single regulator is the easiest method to ensure that the 1.9-V supplies are greater than the 1.2-V
supplies. If the 1.2-V buses are generated from separate regulators, they must rise and fall together (within 200
mV).
The voltage on a pin, including a transient basis, must not have a voltage that is in excess of the supply voltage
or below ground by more than 150 mV. A pin voltage that is higher than the supply or that is below ground can
be a problem during startup and shutdown of power. Ensure that the supplies to circuits driving any of the input
pins, analog or digital, do not rise faster than the voltage at the LM15851 power pins.
The values in the Absolute Maximum Ratings table must be strictly observed including during power up and
power down. A power supply that produces a voltage spike at power turnon, turnoff, or both can destroy the
LM15851 device. Many linear regulators produce output spiking at power on unless there is a minimum load
provided. Active devices draw very little current until the supply voltages reach a few hundred millivolts. The
result can be a turn-on spike that destroys the LM15851 device, unless a minimum load is provided for the
supply. A 100-Ω resistor at the regulator output provides a minimum output current during power up to ensure
that no turn-on spiking occurs. Whether a linear or switching regulator is used, TI recommends using a soft-start
circuit to prevent overshoot of the supply.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
75
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
10 Layout
10.1 Layout Guidelines
Proper grounding and proper routing of all signals is essential to ensure accurate conversion. Each ground layer
should be a single unified ground plane, rather than splitting the ground planes into analog and digital areas.
Because digital switching transients are composed largely of high frequency components, the skin effect dictates
that the total ground-plane copper weight has little effect upon the logic-generated noise. Total surface area is
more important than the total ground-plane volume. Coupling between the typically-noisy digital circuitry and the
sensitive analog circuitry can lead to poor performance that can be impossible to isolate and remedy. The
solution is to keep the analog circuitry well separated from the digital circuitry.
High-power digital components must not be located on or near any linear component or power-supply trace or
plane that services analog or mixed-signal components because the resulting common return current path could
cause fluctuation in the analog input ground return of the ADC which causes excessive noise in the conversion
result.
In general, assume that analog and digital lines must cross each other at 90° to avoid digital noise into the
analog path. In high frequency systems, however, avoid crossing analog and digital lines altogether. The input
clock lines must be isolated from all other lines, both analog and digital. The generally-accepted 90° crossing
must be avoided because even a same amount of coupling causes problems at high frequencies. Best
performance at high frequencies is obtained with a straight signal path.
Coupling onto or between the clock and input signal paths must be avoided using any isolation techniques
available including distance isolation, orientation planning to prevent field coupling of components like inductors
and transformers, and providing well coupled reference planes. Via stitching around the clock signal path and the
input analog signal path provides a quiet ground reference for the critical signal paths and reduces noise
coupling onto these paths. Sensitive signal traces must not cross other signal traces or power routing on
adjacent PCB layers, rather a ground plane must separate the traces. If necessary, the traces should cross at
90° angles to minimize crosstalk.
Isolation of the analog input is important because of the low-level drive required of the LM15851 device. Quality
analog input signal and clock signal path layout is required for full dynamic performance. Symmetry of the
differential signal paths and discrete components in the path is mandatory and symmetrical shunt-oriented
components should have a common grounding via. The high frequency requirements of the input and clock
signal paths necessitate using differential routing with controlled impedances and minimizing signal path stubs
(including vias) when possible.
Layout of the high-speed serial-data lines is of particular importance. These traces must be routed as tightly
coupled 100-Ω differential pairs, with minimal vias. When vias must be used, care must be taken to implement
control-impedance vias (that is, 50-Ω) with adjacent ground vias for image current control.
10.2 Layout Example
The following examples show layout-example plots (top and bottom layers only). Figure 81 shows a typical
stackup for a 10 layer board.
76
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
Layout Example (continued)
Straight DEVCLK
path with minimal
adjacent circuitry.
52
54
53
55
58
56
59
57
61
60
62
65
64
63
67
VBG
DNC
RSV
VA12
TDIODE+
TDIODE±
VA19
RSV2
VA19
SCS
SCLK
SDI
SDO
VD12
DS7+/NCO_2
DS7-/NCO_2
VD12
Power supply decoupling
capacitors very close to
power pins.
1
51
2
50
3
49
Power supply
decoupling
capacitors near
VIN and
DEVCLK are
located on
opposite side of
board to
minimize noise
coupling.
4
5
6
7
8
9
10
11
12
13
14
15
16
DS6+/NCO_1
DS6±/NCO_1
VD12
DS5+/NCO_0
DS5±/NCO_0
VD12
DS4+
DS4±
VD12
DS3+
DS3±
VD12
DS2+
DS2±
VD12
DS1+
DS1±
48
47
46
45
44
43
42
41
40
39
38
37
36
32
34
31
33
30
29
28
27
26
25
24
21
23
35
22
17
AC coupling capacitors on
serial output pairs.
VA12
SYSREF+
SYSREF±
VA12
SYNC~+
SYNC~±
VA19
OR_T0
OR_T1
VA19
VD12
VNEG_OUT
SYNC~
VD12
DS0±
DS0+
VD12
DEVCLK path B
selected if
capacitors
installed here.
66
68
RBIAS+
RBIAS±
VCMO
VA19
VNEG
VA12
VA19
VIN+
VIN±
VA19
VA12
VNEG
VA19
VA12
DEVCLK+
DEVCLK±
VA12
20
Balun transformer for SE
to differential conversion.
18
Straight analog
input path with
minimal adjacent
circuitry.
Large bulk
decoupling
capacitor
near device.
19
Single ended VIN
path via balun
selected if
capacitors
installed here.
GND reference
vias near where
high speed
signals transition
to inner layer.
Figure 79. LM15851 Layout Example 1 — Top Side
Additional decoupling
capacitors near device.
52
53
54
55
56
58
59
57
61
60
62
63
65
64
68
51
50
3
49
4
48
Decoupling
capacitors
power pins near
VIN and
DEVCLK on this
side of board.
5
6
7
8
9
10
11
12
47
46
45
44
43
42
41
40
13
39
33
34
32
31
30
29
28
27
26
25
24
35
23
17
22
36
21
37
16
20
38
15
19
14
DS6+/NCO_1
DS6±/NCO_1
VD12
DS5+/NCO_0
DS5±/NCO_0
VD12
DS4+
DS4±
VD12
DS3+
DS3±
VD12
DS2+
DS2±
VD12
DS1+
DS1±
VA12
SYSREF+
SYSREF±
VA12
SYNC~+
SYNC~±
VA19
OR_T0
OR_T1
VA19
VD12
VNEG_OUT
SYNC~
VD12
DS0±
DS0+
VD12
DEVCLK path A
selected if
capacitors
installed here.
67
1
2
18
Optional differential VIN
path selected if
capacitors or resistors
installed here.
RBIAS+
RBIAS±
VCMO
VA19
VNEG
VA12
VA19
VIN+
VIN±
VA19
VA12
VNEG
VA19
VA12
DEVCLK+
DEVCLK±
VA12
66
VBG
DNC
RSV
VA12
TDIODE+
TDIODE±
VA19
RSV2
VA19
SCS
SCLK
SDI
SDO
VD12
DS7+/NCO_2
DS7-/NCO_2
VD12
RBIAS resistor
near to RBIAS+
and RBIASpins.
Larger bulk
decoupling capacitors
on this side of board,
near device.
Figure 80. LM15851 Layout Example 2 — Bottom Side
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
77
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Layout Example (continued)
L1 ± SIG
0.0040''
L2 ± GND
0.0067''
L3 ± SIG
0.0060''
L4 ± GND
0.0041''
L5 ± PWR
0.0060''
0.0578''
L6 ± SIG
0.0067''
L7 ± GND
0.0040''
L8 ± SIG
0.0073''
L9 ± GND
0.0040''
L10 ± SIG
1/2 oz. Copper on L1, L3, L6, L8, L10
1 oz. Copper on L2, L4, L5, L7, L9
100 Differential Signaling on SIG Layers
Low loss dielectric adjacent very high speed trace layers
Finished thickness 0.0620" including plating and solder mask
Figure 81. LM15851 Typical Stackup — 10 Layer Board
78
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
10.3 Thermal Management
The LM15851 device is capable of impressive speeds and performance at low power levels for speed. However,
the power consumption is still high enough to require attention to thermal management. The VQFN package has
a primary-heat transfer path through the center pad on the bottom of the package. The thermal resistance of this
path is provided as RθJCbot.
For reliability reasons, the die temperature must be kept to a maximum of 135°C which is the ambient
temperature (TA) plus the ADC power consumption multiplied by the net junction-to-ambient thermal resistance
(RθJA). Maintaining this temperature is not a problem if the ambient temperature is kept to a maximum of 85°C as
specified in the Recommended Operating Conditions table and the center ground pad on the bottom of the
package is thermally connected to a large-enough copper area of the PC board.
The package of the LM15851 device has a center pad that provides the primary heat-removal path as well as
excellent electrical grounding to the PCB. Recommended land pattern and solder paste examples are provided in
the Mechanical, Packaging, and Orderable Information section. The center-pad vias shown must be connected to
internal ground planes to remove the maximum amount of heat from the package, as well as to ensure best
product parametric performance.
If needed to further reduce junction temperature, TI recommends to build a simple heat sink into the PCB which
occurs by including a copper area of about 1 to 2 cm2 on the opposite side of the PCB. This copper area can be
plated or solder-coated to prevent corrosion, but should not have a conformal coating which would provide
thermal insulation. Thermal vias will be used to connect these top and bottom copper areas and internal ground
planes. These thermal vias act as heat pipes to carry the thermal energy from the device side of the board to the
opposite side of the board where the heat can be more effectively dissipated.
11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.1.2 Development Support
For the ADC Harmonic Calculator, got to http://www.ti.com/tool/adc-harmonic-calc.
11.1.3 Device Nomenclature
Aperture (sampling) Delay is the amount of delay, measured from the sampling edge of the clock input, after
which the signal present at the input pin is sampled inside the device.
Aperture Jitter (t(AJ)) is the variation in aperture delay from sample to sample. Aperture jitter appears as input
noise.
Clock Duty Cycle is the ratio of the time that the clock waveform is at a logic high to the total time of one clock
period.
Full Power Bandwidth (FPBW) is a measure of the frequency at which the reconstructed output fundamental
drops 3 dB below the low frequency value for a full scale input.
Interleaving Spurs are frequency domain (FFT) artifacts resulting from non-idealities in the multi-bank
interleaved architecture of the ADC.
Offset errors between banks result in fixed spurs at ƒS / 4 and ƒS / 2. Gain and timing errors result
in input-signal-dependent spurs at ƒS / 4 ± FIN and ƒS / 2 ± FIN.
Intermodulation Distortion (IMD) is the creation of additional spectral components as a result of two sinusoidal
frequencies being applied to the ADC input at the same time. IMD is defined as the ratio of the
power in the second-order and third-order intermodulation products to the power in one of the
original frequencies. IMD is usually expressed in dBFS.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
79
LM15851
SLAS990D – JANUARY 2014 – REVISED JULY 2015
www.ti.com
Device Support (continued)
Least Significant Bit (LSB ) is the bit that has the smallest value or weight of all bits. This value is calculated
with Equation 18.
VFS(dif) / 2n
where
•
•
VFS(dif) is the differential full-scale amplitude of VI as set by the FSR input (pin 14)
n is the ADC resolution in bits, which is 12 for the LM15851 device
(18)
CML Differential Output Voltage (VOD) is the absolute value of the difference between the positive and
negative outputs. Each output is measured with respect to Ground.
VD+
VD VOD
VD+
VOS
VD GND
VOD = | VD+ - VD- |
CML Output Signal Levels
CML Output Offset Voltage (VO(ofs)) is the midpoint between the D+ and D– pins output voltage. Equation 19 is
an example of VOS.
[(VD+) + ( VD–)] / 2
(19)
Most Significant Bit (MSB) is the bit that has the largest value or weight. The value of the MSB is one half of
full scale.
Overrange Recovery Time is the time required after the differential input voltages goes from ±1.2 V to 0 V for
the converter to recover and make a conversion with its rated accuracy.
Other Spurs is the sum of all higher harmonics (fourth and above), interleaving spurs, and any other fixed or
input-dependent spurs.
Data Delay (Latency) is the number of input clock cycles between initiation of conversion and when related data
is present at the serializer output.
Spurious-free Dynamic Range (SFDR) is the difference, expressed in dB, between the RMS values of the input
signal at the output and the peak spurious signal, where a spurious signal is any signal present in
the output spectrum that is not present at the input, excluding DC.
Total Harmonic Distortion (THD) is the ratio expressed in dB, of the RMS total of the first nine harmonic levels
at the output to the level of the fundamental at the output. THD is calculated with Equation 20.
THD = 20 x log
A 2 +... +A 2
f2
f10
A f12
where
•
•
A(f1) is the RMS power of the fundamental (output) frequency
A(f2) through A(f10) are the RMS power of the first nine harmonic frequencies in the output spectrum (20)
Second Harmonic Distortion (2nd Harm) is the difference, expressed in dB, between the RMS power in the
input frequency detected at the output and the power in the second harmonic level at the output.
Third Harmonic Distortion (3rd Harm) is the difference, expressed in dB, between the RMS power in the input
frequency seen at the output and the power in the third harmonic level at the output.
Word Error Rate is the probability of error and is defined as the probable number of errors per unit of time
divided by the number of words seen in that amount of time. A Word Error Rate of 10–18
corresponds to a statistical error in one conversion about every four years.
80
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
LM15851
www.ti.com
SLAS990D – JANUARY 2014 – REVISED JULY 2015
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
• LMH3401 7-GHz, Ultra-Wideband, Fixed-Gain, Fully-Differential Amplifier, SBOS695
• LMK0482x Ultra Low-Noise JESD204B Compliant Clock Jitter Cleaner with Dual Loop PLLs, SNAS605
• LMX2581 Wideband Frequency Synthesizer with Integrated VCO, SNAS601
• TRF3765 Integer-N/Fractional-N PLL with Integrated VCO, SLWS230
11.3 Community Resource
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated
Product Folder Links: LM15851
81
PACKAGE OPTION ADDENDUM
www.ti.com
30-Jun-2015
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LM15851NKE
ACTIVE
VQFN
NKE
68
168
Green (RoHS
& no Sb/Br)
CU SN | Call TI
Level-3-260C-168 HR
-40 to 85
LM15851
LM15851NKE10
ACTIVE
VQFN
NKE
68
10
Green (RoHS
& no Sb/Br)
Call TI
Level-3-260C-168 HR
-40 to 85
LM15851
LM15851NKER
ACTIVE
VQFN
NKE
68
2000
Green (RoHS
& no Sb/Br)
CU SN | Call TI
Level-3-260C-168 HR
-40 to 85
LM15851
LM15851NKET
ACTIVE
VQFN
NKE
68
250
Green (RoHS
& no Sb/Br)
CU SN | Call TI
Level-3-260C-168 HR
-40 to 85
LM15851
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4)
There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5)
Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
30-Jun-2015
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE OUTLINE
NKE0068A
VQFN - 0.9 mm max height
SCALE 1.700
PLASTIC QUAD FLATPACK - NO LEAD
10.1
9.9
B
A
PIN 1 ID
10.1
9.9
0.9 MAX
C
SEATING PLANE
7.7 0.1
4X (45 X0.42)
18
34
17
35
SYMM
4X
8
1
64X 0.5
0.1 C
0.05
0.00
(0.2)
51
52
68
PIN 1 ID
(OPTIONAL)
SYMM
68X
0.7
0.5
68X
0.3
0.2
0.1
0.05
C A
C
B
4214820/A 12/2014
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
www.ti.com
EXAMPLE BOARD LAYOUT
NKE0068A
VQFN - 0.9 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
( 7.7)
SYMM
68X (0.8)
(1.19) TYP
52
68
68X (0.25)
1
51
(1.19)
TYP
64X (0.5)
SYMM
(9.6)
( 0.2) TYP
VIA
35
17
34
18
(9.6)
LAND PATTERN EXAMPLE
SCALE:8X
0.07 MAX
ALL AROUND
0.07 MIN
ALL AROUND
SOLDER MASK
OPENING
METAL
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
(PREFERRED)
METAL UNDER
SOLDER MASK
SOLDER MASK
DEFINED
SOLDER MASK DETAILS
4214820/A 12/2014
NOTES: (continued)
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
number SLUA271 (www.ti.com/lit/slua271).
www.ti.com
EXAMPLE STENCIL DESIGN
NKE0068A
VQFN - 0.9 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
(9.6)
(1.19) TYP
68X (0.8)
68
36X
( 0.99)
52
68X (0.25)
1
51
(1.19)
TYP
64X (0.5)
SYMM
(9.6)
METAL
TYP
35
17
18
34
SYMM
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
EXPOSED PAD
60% PRINTED SOLDER COVERAGE BY AREA
SCALE:8X
4214820/A 12/2014
NOTES: (continued)
5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
www.ti.com
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other
changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest
issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and
complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale
supplied at the time of order acknowledgment.
TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms
and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary
to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily
performed.
TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and
applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or
other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information
published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or
endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the
third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration
and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered
documentation. Information of third parties may be subject to additional restrictions.
Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service
voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice.
TI is not responsible or liable for any such statements.
Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements
concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support
that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which
anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause
harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use
of any TI components in safety-critical applications.
In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to
help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and
requirements. Nonetheless, such components are subject to these terms.
No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties
have executed a special agreement specifically governing such use.
Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in
military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components
which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and
regulatory requirements in connection with such use.
TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of
non-designated products, TI will not be responsible for any failure to meet ISO/TS16949.
Products
Applications
Audio
www.ti.com/audio
Automotive and Transportation
www.ti.com/automotive
Amplifiers
amplifier.ti.com
Communications and Telecom
www.ti.com/communications
Data Converters
dataconverter.ti.com
Computers and Peripherals
www.ti.com/computers
DLP® Products
www.dlp.com
Consumer Electronics
www.ti.com/consumer-apps
DSP
dsp.ti.com
Energy and Lighting
www.ti.com/energy
Clocks and Timers
www.ti.com/clocks
Industrial
www.ti.com/industrial
Interface
interface.ti.com
Medical
www.ti.com/medical
Logic
logic.ti.com
Security
www.ti.com/security
Power Mgmt
power.ti.com
Space, Avionics and Defense
www.ti.com/space-avionics-defense
Microcontrollers
microcontroller.ti.com
Video and Imaging
www.ti.com/video
RFID
www.ti-rfid.com
OMAP Applications Processors
www.ti.com/omap
TI E2E Community
e2e.ti.com
Wireless Connectivity
www.ti.com/wirelessconnectivity
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2015, Texas Instruments Incorporated
Similar pages