TI1 LMX2594 15 ghz wideband pllatinum rf synthesizer with phase synchronization and jesd204b support Datasheet

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LMX2594
SNAS696 – MARCH 2017
LMX2594 15 GHz Wideband PLLatinum™ RF Synthesizer
With Phase Synchronization and JESD204B Support
1 Features
3 Description
•
•
The LMX2594 is a high-performance, wideband PLL
with integrated VCOs that can generate any
frequency from 10 MHz to 15 GHz without using an
internal doubler, thus eliminating the need for subharmonic filters. The high performance PLL with
figure of merit of –236 dBc/Hz and high phase
detector frequency can attain very low in-band noise
and integrated jitter. The high speed N-divider has no
pre-divider, thus significantly reducing the amplitude
and number of spurs. There is also a programmable
input multiplier to mitigate integer boundary spurs.
1
•
•
•
•
•
•
•
•
•
10-MHz to 15-GHz Output Frequency
–110 dBc/Hz Phase Noise at 100 kHz Offset With
15 GHz Carrier
45-fs rms Jitter at 7.5 GHz (100 Hz to 100 MHz)
Programmable Output Power Up to 7 dBm at 15
GHz
PLL Key Specifications
– Figure of Merit: –236 dBc/Hz
– Normalized 1/f Noise: –129 dBc/Hz
– High Phase Detector Frequency
– 400-MHz Integer Mode
– 300-MHz Fractional Mode
– 32-bit Fractional-N Divider
Remove Integer Boundary Spurs With
Programmable Input Multiplier
Synchronize Output Phase Across Multiple
Devices
Support for SYSREF With 9-ps Resolution
Programmable Delay
Frequency Ramp and Chirp Generation Ability for
FMCW Applications
< 20-µs VCO Calibration Speed
3.3-V Single Power Supply Operation
The LMX2594 allows users to synchronize the output
of multiple devices and also enables applications that
need deterministic delay between input and output. A
frequency ramp generator can synthesize up to 2
segments of ramp in an automatic ramp generation
option or a manual option for maximum flexibility. The
fast calibration algorithm allows changing frequencies
faster than 20 µs. The LMX2594 adds support for
generating or repeating SYSREF (compliant to
JESD204B standard) making it an ideal low-noise
clock source for high-speed data converters. Fine
delay adjustment (9 ps resolution) is provided in this
configuration to account for delay differences of
board traces.
The output drivers within LMX2594 delivers output
power as high as 7 dBm at 15 GHz carrier frequency.
The device runs from a single 3.3 V supply and has
integrated LDOs that eliminate the need for on-board
low noise LDOs.
2 Applications
•
•
•
•
•
•
5G and mm-wave Wireless Infrastructure
Test and Measurement Equipment
Radar
MIMO
Phased Array Antennas and Beam Forming
High Speed Data Converter Clocking (Supports
JESD204B)
Device Information(1)
PART NUMBER
LMX2594
PACKAGE
VQFN (40)
BODY SIZE (NOM)
6.00 mm × 6.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
Loop Filter
CPout
Phase
Detector
OSCinP
OSCin
Douber
Input
signal
Pre-R
Divider
Multiplier
Post-R
Divider
I
Vtune
Charge
Pump
RFoutAP
MUX
OSCinM
Sigma-Delta
Modulator
MUXout
RFoutAM
Channel
Divider
RFoutBM
CSB
SCK
SDI
MUX
Serial Interface
Control
Vcc
Vcc
RFoutBP
N Divider
SYSREF
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.
LMX2594
SNAS696 – MARCH 2017
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
7
7.5 Programming........................................................... 41
7.6 Register Maps and Descriptions ............................ 41
1
1
1
2
3
5
8
8.1 Application Information............................................ 58
8.2 Typical Application ................................................. 60
9 Power Supply Recommendations...................... 63
10 Layout................................................................... 64
Absolute Maximum Ratings ...................................... 5
ESD Ratings.............................................................. 5
Recommended Operating Conditions....................... 5
Thermal Information .................................................. 5
Electrical Characteristics........................................... 6
Timing Requirements ................................................ 8
Typical Characteristics ............................................ 10
10.1 Layout Guidelines ................................................. 64
10.2 Layout Example .................................................... 65
11 Device and Documentation Support ................. 66
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Detailed Description ............................................ 21
7.1
7.2
7.3
7.4
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Application and Implementation ........................ 58
21
22
22
40
Device Support......................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
66
66
66
66
66
66
66
12 Mechanical, Packaging, and Orderable
Information ........................................................... 67
4 Revision History
2
DATE
REVISION
March 2017
*
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NOTES
Initial release
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5 Pin Configuration and Functions
GND
RampDir
VbiasVARAC
GND
Vtune
VrefVCO
VccVCO
VregVCO
GND
GND
RHA Package
40-Pin VQFN
Top View
CE
RampClk
GND
VrefVCO2
VbiasVCO
SysRefReq
GND
VbiasVCO2
SYNC
VccVCO2
GND
GND
GND
VccDIG
CSB
OSCinP
RFoutAP
OSCinM
RFoutAM
MUXout
RFoutBP
RFoutBM
SDI
SCK
VccMASH
GND
GND
CPout
VccBUF
VccCP
VregIN
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Pin Functions
PIN
NO.
NAME
1
I/O
DESCRIPTION
CE
Input
GND
Ground
VCO ground
3
VbiasVCO
Bypass
VCO bias. Requires connecting 10 µF capacitor to VCO ground. Place close to pin.
5
SYNC
Input
6, 14
GND
Ground
Digital ground
7
VccDIG
Supply
Digital supply. TI recommends bypassing with a 0.1 µF capacitor to digital ground.
8
OSCinP
Input
Reference input clock (+). High-impedance self-biasing pin. Requires AC coupling capacitor.
(0.1 µF recommended)
9
OSCinM
Input
Reference input clock (–). High impedance self-biasing pin. Requires AC coupling capacitor.
(0.1 µF recommended)
10
VregIN
Bypass
Input reference path regulator output. Requires connecting 1 µF capacitor to ground. Place
close to pin.
11
VccCP
Supply
Charge pump supply.TI recommends bypassing with a 0.1 µF capacitor to charge pump
ground.
12
CPout
Output
Charge pump output. TI recommends connecting C1 of loop filter close to pin.
13
GND
Ground
Charge pump ground
15
VccMASH
Supply
Digital supply. TI recommends bypassing with a 0.1 µF and 10 µF capacitor to digital ground.
16
SCK
Input
SPI clock. High impedance CMOS input. 1.8 to 3.3 V logic.
17
SDI
Input
SPI data. High impedance CMOS input. 1.8 to 3.3 V logic.
18
RFoutBM
Output
Differential output B (–). Requires pullup (typically 50-Ω resistor) to VCC as close as possible
to pin. Can be used as an output signal or SYSREF output.
19
RFoutBP
Output
Differential output B (+). Requires pullup (typically 50-Ω resistor) to VCC as close as possible
to pin. Can be used as an output signal or SYSREF output.
2, 4, 25, 31,
34, 39, 40
Chip enable input. Active HIGH powers on the device.
Phase synchronization pin. Has programmable threshold.
20
MUXout
Output
Multiplexed output pin — lock detect, readback, diagnostics, ramp status
21
VccBUF
Supply
Output buffer supply. TI recommends bypassing with a 0.1 µF capacitor to RFout ground.
22
RFoutAM
Output
Differential output A (–). Requires connecting 50-Ω resistor pullup to Vcc as close as
possible to pin.
23
RFoutAP
Output
Differential output A (+). Requires connecting 50-Ω resistor pullup to Vcc as close as
possible to pin.
24
CSB
Input
SPI latch. Chip Select Bar . High-impedance CMOS input. 1.8 to 3.3 V logic.
26
VccVCO2
Supply
VCO supply. TI recommends bypassing with a 0.1 µF and 10 µF capacitor to VCO ground.
27
VbiasVCO2
Bypass
VCO bias. Requires connecting 1 µF capacitor to VCO ground.
28
SysRefReq
Input
29
VrefVCO2
Bypass
30
RampClk
Input
Input pin for ramping mode that can be used to clock the ramp in manual ramping mode or
as a trigger input.
32
RampDir
Input
Input pin for ramping mode that can be used to change ramp direction in manual ramping
mode or as a trigger input.
33
VbiasVARAC
Bypass
35
Vtune
Input
36
VrefVCO
Bypass
VCO supply reference. Requires connecting 10 µF capacitor to ground.
37
VccVCO
Supply
VCO supply. Recommend bypassing with 0.1 µF and 10 µF capacitor to ground.
38
VregVCO
Bypass
VCO regulator node. Requires connecting 1 µF capacitor to ground.
GND
Ground
RFout ground
DAP
4
SYSREF request input for JESD204B support
VCO supply reference. Requires connecting 10 µF capacitor to VCO ground.
VCO Varactor bias. Requires connecting 10 µF capacitor to VCO ground.
VCO tuning voltage input.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
VCC
Power supply voltage
–0.3
3.6
V
TJ
Junction temperature
–40
150
°C
Tstg
Storage temperature
–65
150
°C
(1)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±750
UNIT
V
JEDEC document JEP155 states that 500 V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 500 V HBM is possible with the necessary precautions. Pins listed as ±XXX V may actually have higher performance.
JEDEC document JEP157 states that 250 V CDM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 250 V CDM is possible with the necessary precautions. Pins listed as ±YYY V may actually have higher performance.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
UNIT
VCC
Power supply voltage
3.15
3.3
3.45
V
TA
Ambient temperature
–40
25
85
°C
TJ
Junction Temperature
125
°C
6.4 Thermal Information
LMX2594
THERMAL METRIC (1)
RHA (VQFN)
UNIT
40 PINS
RθJA
Junction-to-ambient thermal resistance
RθJC(top)
Junction-to-case (top) thermal resistance
30.5
°C/W
15.3
°C/W
RθJB
ψJT
Junction-to-board thermal resistance
5.4
°C/W
Junction-to-top characterization parameter
0.2
°C/W
ψJB
Junction-to-board characterization parameter
5.3
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
0.9
°C/W
(1)
(2)
(2)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
DAP
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6.5 Electrical Characteristics
3.15 V ≤ VCC ≤ 3.45 V, –40°C ≤ TA ≤ +85°C. Typical values are at VCC = 3.3 V, 25°C (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
3.15
3.3
3.45
V
POWER SUPPLY
VCC
Supply voltage
OUTA_PD = 0, OUTB_PD = 1
OUTA_MUX = OUTB_MUX = 1
OUTA_PWR = 31, CPG=7
fOSC= fPD = 100 MHz, fVCO = fOUT = 14 GHz
pOUT = 3 dBm with 50-Ω resistor pullup
340
Power on reset current
RESET=1
170
Power down current
POWERDOWN=1
Supply current
ICC
mA
5
OUTPUT CHARACTERISTICS
Single-ended output power (1)
pOUT
50-Ω resistor pullup
OUTx_PWR = 50
fOUT = 8 GHz
fOUT = 15 GHz
2
1-nH inductor pullup
OUTx_PWR = 50
fOUT = 8 GHz
10
fOUT = 15 GHz
7
Xtalk
Isolation between outputs A and OUTA_MUX = VCO
B. Measured on output A
OUTB_MUX = channel divider
H2
Second Harmonic (1)
H3
Third Harmonic (1)
5
dBm
–50
dBc
OUTA_MUX = VCO
fVCO = 8 GHz
-20
dBc
OUTA_MUX = VCO
fVCO = 8 GHz
-50
dBc
INPUT SIGNAL PATH
OSC_2X = 0
fOSCin
Reference input frequency
vOSCin
Reference input voltage
AC-coupled required
Input range
fMULT
Multiplier frequency (only
applies when multiplier is
enabled)
OSC_2X = 1
(2)
5
1400
5
200
0.2
2
30
70
180
250
0.125
400
FRAC_ORDER = 1,2,3
5
300
FRAC_ORDER = 4
5
240
Output range
MHz
Vpp
MHz
PHASE DETECTOR AND CHARGE PUMP
Integer mode
fPD
Phase detector frequency
(2)
Charge-pump leakage current
Effective charge pump current.
This is the sum of the up and
down currents
ICPout
Fractional mode
FRAC_ORDER = 0
CPG = 0
15
CPG = 4
3
CPG = 1
6
CPG = 5
9
CPG = 3
12
CPG = 7
PNPLL_1/f
Normalized PLL 1/f noise
PNPLL_flat Normalized PLL noise floor
(1)
(2)
(3)
6
MHz
nA
mA
15
fPD = 100 MHz, fVCO = 12 GHz (3)
–129
dBc/Hz
–236
dBc/Hz
Output power, spurs, and harmonics can vary based on board layout and components.
For lower VCO frequencies, the N divider minimum value can limit the phase-detector frequency.
The PLL noise contribution is measured using a clean reference and a wide loop bandwidth and is composed into flicker and flat
components. PLL_flat = PLL_FOM + 20 × log(Fvco/Fpd) + 10 × log(Fpd / 1Hz). PLL_flicker (offset) = PLL_flicker_Norm + 20*log(Fvco /
1GHz) – 10*log(offset / 10kHz). Once these two components are found, the total PLL noise can be calculated as PLL_Noise = 10 ×
log(10 PLL_Flat / 10 + 10 PLL_flicker / 10 )
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Electrical Characteristics (continued)
3.15 V ≤ VCC ≤ 3.45 V, –40°C ≤ TA ≤ +85°C. Typical values are at VCC = 3.3 V, 25°C (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VCO CHARACTERISTICS
VCO1
fVCO = 8.0 GHz
VCO2
fVCO = 9.2 GHz
VCO3
fVCO = 10.3 GHz
PNVCO
VCO phase noise
VCO4
fVCO = 11.3 GHz
VCO5
fVCO = 12.5 GHz
VCO6
fVCO = 13.3 GHz
VCO7
fVCO = 14.5 GHz
tVCOCAL
VCO Calibration Speed, Switch
Across the entire frequency
Band, fOSC = 200 MHz, fPD =
100 MHz
(4)
(4)
10 kHz
– 80
100 kHz
– 107
1 MHz
– 128
10 MHz
– 148
90 MHz
– 157
10 kHz
– 79
100 kHz
– 105
1 MHz
– 127
10 MHz
– 147
90 MHz
– 157
10 kHz
– 77
100 kHz
– 104
1 MHz
– 126
10 MHz
– 147
90 MHz
– 157
10 kHz
– 76
100 kHz
– 103
1 MHz
– 125
10 MHz
– 145
90 MHz
– 158
10 kHz
– 74
100 kHz
– 100
1 MHz
– 123
10 MHz
– 144
90 MHz
– 157
10 kHz
– 73
100 kHz
– 100
1 MHz
– 122
10 MHz
– 143
90 MHz
– 155
10 kHz
– 73
100 kHz
–99
1 MHz
– 121
10 MHz
– 143
90 MHz
– 152
No assist
50
Partial assist
35
Close frequency
20
Full assist
dBc/Hz
µs
5
See Application and Implementation for more details on the different VCO calibration modes.
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Electrical Characteristics (continued)
3.15 V ≤ VCC ≤ 3.45 V, –40°C ≤ TA ≤ +85°C. Typical values are at VCC = 3.3 V, 25°C (unless otherwise noted).
PARAMETER
KVCO
VCO Gain
TEST CONDITIONS
MIN
TYP
8.0 GHz
73
9.2 GHz
76
10.3 GHz
94
11.3 GHz
86
12.5 GHz
149
13.3 GHz
135
14.5 GHz
154
|ΔTCL|
Allowable temperature drift
when VCO is not re-calibrated
RAMP_EN = 0 or RAMP_MANUAL= 1
125
H2
VCO second harmonic
fVCO = 8 GHz, divider disabled
–20
H3
VCO third haromonic
fVCO = 8 GHz, divider disabled
–50
MAX
UNIT
MHz/V
°C
dBc
SYNC PIN AND PHASE ALIGNMENT
fOSCinSY
NC
Maximum usable OSCin with
sync pin
Figure 22
Category 3
0
100
Categories1 and 2
0
1400
MHz
DIGITAL INTERFACE, Applies to SCLK, SDA, CSB, RampDir, RampCLK, MUXout, SYNC (CMOS Mode), SysRefReq (CMOS Mode)
VIH
High level input voltage
1.4
Vcc
VIL
IIH
IIL
Low level input voltage
0
0.4
V
High level input current
–25
25
µA
Low level input current
–25
25
µA
VCC –
0.4
V
VOH
High level output voltage
VOL
High level output current
Load current = –10 mA
MUXout pin
Load current = 10 mA
0.4
V
V
6.6 Timing Requirements
(3.15 V ≤ VCC ≤ 3.45 V, –40°C ≤ TA ≤ +85°C, except as specified. Nominal values are at VCC = 3.3 V, TA = 25°C)
MIN
NOM
MAX
UNIT
SYNC, SYSRefReq, RampCLK, and RampDIR Pins
tSETUP
Setup time for pin relative to OSCin rising
edge
SYNC pin
2.5
SysRefReq pin
2.5
tHOLD
Hold time for SYNC pin relative to OSCin
rising edge
SYNC pin
2
SysRefReq pin
2
ns
ns
DIGITAL INTERFACE WRITE SPECIFICATIONS
fSPIWrite
SPI write speed
tES
Clock to enable low time
5
ns
tCS
Data to clock setup time
2
ns
tCH
Data to clock hold time
2
ns
tCWH
Clock pulse width high
5
ns
tCWL
Clock pulse width low
5
ns
tCES
Enable to clock setup time
5
ns
tEWH
Enable pulse width high
2
ns
8
tCWL + tCWH > 13.333 ns
See Figure 1
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75
MHz
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Timing Requirements (continued)
(3.15 V ≤ VCC ≤ 3.45 V, –40°C ≤ TA ≤ +85°C, except as specified. Nominal values are at VCC = 3.3 V, TA = 25°C)
MIN
NOM
MAX
UNIT
50
MHz
DIGITAL INTERFACE READBACK SPECIFICATIONS
fSPIReadb
ack
SPI readback speed
tES
Clock to enable low time
tCS
Clock to data wait time
tCWH
Clock pulse width high
tCWL
10
ns
10
See Figure 2
ns
10
ns
Clock pulse width low
10
ns
tCES
Enable to clock setup time
10
ns
tEWH
Enable pulse width high
10
ns
MSB
SDK
LSB
R/W
A5
A0
D15
D14
D0
SDA
tCS
tCES
tCH
tCWH
tCE
tCWL
CSB
tEWH
Figure 1. Serial Data Input Timing Diagram
There are several other considerations for writing on the SPI:
• The R/W bit must be set to 0.
• The data on SDA pin is clocked into a shift register on each rising edge on the SCK pin.
• The CSB must be held low for data to be clocked. Device will ignore clock pulses if CSB is held high.
• The CSB transition from high to low must occur when SCK is low.
• When SCK and SDA lines are shared between devices, TI recommends hold the CSB line high on the device
that is not to be clocked.
LSB
RB15
MUXout
RB14
RB0
MSB
SDA
R/W
A6
A5
A0
SCK
tCES
tCS
tCWH
tCE
tCWL
CSB
tEWH
Figure 2. Serial Data Readback Timing Diagram
There are several other considerations for SPI readback:
• The R/W bit must be set to 1.
• The MUXout pin will always be low for the address portion of the transaction.
• The data on SDA is clocked out on the rising edge of SCK.
• The data portion of the transition on the SDA line is always ignored.
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6.7 Typical Characteristics
-80
Figure 3. Closed Loop Phase Noise With fOSC = 100 MHz and fPD = 200 MHz
-85
-90
-95
-100
-105
-110
-115
-120
1.E+02
1.E+03
1.E+04
1.E+05
Flicker (PLL 1/f =-129.2 dBc/Hz)
Flat (FOM = -236.2 dBc/Hz)
Modeled Phase Noise
Measurement
Figure 4. Calculation of PLL Noise Metrics of PLL fPD=100 MHz, fVCO = 12 GHz
10
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Output Power (dBm)
Typical Characteristics (continued)
14.0
13.0
12.0
11.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
3000
5000
7000
9000
11000
13000
15000
Frequeny (MHz)
Resistor Pull-up (OUTx_PWR=50)
Inductor Pull-Up (OUTx_PWR=50)
Figure 5. Output Power vs Pullup
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Typical Characteristics (continued)
Figure 6. Closed Loop Phase Noise at 15 GHz With fOSC = 100 MHz and fPD = 200 MHz
12
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Typical Characteristics (continued)
Figure 7. Closed Loop Phase Noise at 13 GHz With fOSC = 100 MHz and fPD = 200 MHz
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Typical Characteristics (continued)
Figure 8. Closed Loop Phase Noise at 11 GHz With fOSC = 100 MHz and fPD = 200 MHz
14
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Typical Characteristics (continued)
Figure 9. Closed Loop Phase Noise at 9 GHz With fOSC = 100 MHz and fPD = 200 MHz
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Typical Characteristics (continued)
Figure 10. Closed Loop Phase Noise at 7.5 GHz With fOSC = 100 MHz and fPD = 200 MHz
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Typical Characteristics (continued)
Figure 11. Closed Loop phase noise at 3.5 GHz With fVCO = 100, fOSC = 100 MHz, and fPD = 200 MHz
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Typical Characteristics (continued)
-145
Additive Divider Noise (dBc/Hz)
-150
-155
-160
-165
-170
-175
-180
10
100
1000
Fout (MHz)
Figure 12. Additive VCO Divider Noise Floor
(Adds to the divided far out VCO noise when output divider is used.)
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Typical Characteristics (continued)
Figure 13. VCO Ramping 12 - 12.125 GHz Without Need to Calibrate
16000
15000
Frequency (MHz)
14000
13000
12000
11000
10000
9000
8000
7000
0
2
4
6
8
10
Time (ms)
Figure 14. VCO Ramping 7.5 to 15 GHz Triangle Wave with VCO Calibration
(The glitches in the plot are due to inability of the measurement equipment to track the VCO while
calibrating.)
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Typical Characteristics (continued)
A.
Figure 15. VCO unassisted calibration from 7.5 - 14 GHz in 33.6 µs
CHDIV=2, fOSC=200 MHz, fPD=100 MHz
A.
Figure 16. VCO Calibration with partial assist from 7.5 - 14 GHz in 25.2 µs
CHDIV=2, fOSC = 200 MHz, fPD = 100 MHz.
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7 Detailed Description
7.1 Overview
The LMX2594 is a high-performance, wideband frequency synthesizer with integrated VCO and output divider.
The VCO operates from 7.5 to 15 GHz and this can be combined with the output divider to produce any
frequency in the range of 10 MHz to 15 GHz. Within the input path there are two dividers and a multiplier for
flexible frequency planning. The multiplier also allows reduction of spurs by moving the frequencies away from
the integer boundary.
The PLL is fractional-N PLL with programmable delta-sigma modulator up to 4th order. The fractional
denominator is a programmable 32-bit long, which can provide fine frequency steps easily below 1-Hz resolution
as well as be used to do exact fractions like 1/3, 7/1000, and many others. The phase frequency detector goes
up to 300 MHz in fractional mode or 400 MHz in integer mode, although minimum N divider values must also be
taken into account.
For applications where deterministic or adjustable phase is desired, the SYNC pin can be used to get the phase
relationship between the OSCin and RFout pins deterministic. Once this is done, the phase can be adjusted in
very fine steps of the VCO period divided by the fractional denominator.
The ultra-fast VCO calibration is ideal for applications where the frequency must be swept or abruptly changed.
The frequency can be manually programmed, or the device can be set up to do ramps and chirps.
The JESD204B support includes using the RFoutB output to create a differential SYSREF output that can be
either a single pulse or a series of pulses that occur at a programmable distance away from the rising edges of
the output signal.
The LMX2594 device requires only a single 3.3 V power supply. The internal power supplies are provided by
integrated LDOs, eliminating the need for high performance external LDOs.
The digital logic for the SPI interface and is compatible with voltage levels from 1.8 to 3.3 V.
Table 1 shows the range of several of the dividers, multipliers, and fractional settings.
Table 1. Range of Dividers, Multipliers, and Fractional Settings
PARAMETER
MIN
MAX
Outputs enabled
0
2
COMMENTS
OSCin doubler
0 (1X)
1 (2X)
The low noise doubler can be used to increase the
phase detector frequency to improve phase noise and
avoid spurs. This is in reference to the OSC_2X bit.
Pre-R divider
1 (bypass)
128
Only use the Pre R divider if the multiplier is used and
the input frequency is too high for the multiplier.
Multiplier
3
7
Post-R divider
1 (bypass)
255
The maximum input frequency for the post-R divider is
250 MHz. Use the Pre R divider if necessary.
N divider
≥ 28
524287
The minimum divide depends on modulator order and
VCO frequency. See N Divider and Fractional Circuitry
for more details.
Fractional numerator/
denominator
1 (Integer mode)
232 – 1 = 4294967295
Fractional order
0
4
Channel divider
1 (bypass)
768
Output frequency
10 MHz
15 GHz
This is in reference to the MULT word.
The fractional denominator is programmable and can
assume any value between 1 and 232–1; it is not a
fixed denominator.
Order 0 is integer mode and the order can be
programmed
This is the series of several dividers. Also, be aware
that above 10 GHz, the maximum allowable channel
divider value is 6.
This is implied by the minimum VCO frequency divided
by the maximum channel divider value.
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7.2 Functional Block Diagram
Loop Filter
CPout
Phase
Detector
OSCinP
OSCin
Douber
Input
signal
Pre-R
Divider
Multiplier
Post-R
Divider
Vtune
Charge
Pump
I
RFoutAP
MUX
OSCinM
RFoutAM
Channel
Divider
Sigma-Delta
Modulator
RFoutBM
CSB
SCK
SDI
MUX
Serial Interface
Control
Vcc
Vcc
RFoutBP
N Divider
SYSREF
MUXout
7.3 Feature Description
7.3.1 Reference Oscillator Input
The OSCin pins are used as a frequency reference input to the device. The input is high impedance and requires
AC-coupling caps at the pin. The OSCin pins can be driven single-ended with a CMOS clock or XO. Differential
clock input is also supported, making it easier to interface with high-performance system clock devices such as
TI’s LMK series clock devices. As the OSCin signal is used as a clock for the VCO calibration, a proper
reference signal must be applied at the OSCin pin at the time of programming FCAL_EN.
7.3.2 Reference Path
The reference path consists of an OSCin doubler (OSC_2X), Pre-R divider, multiplier (MULT) and a Post-R
divider.
OSCin
OSCin
Douber
Pre-R
Divider
Multiplier
Post-R
Divider
Phase Frequency Detector
Figure 17. Reference Path Diagram
The OSCin doubler (OSC_2X) can double up low OSCin frequencies. Pre-R (PLL_R_PRE) and Post-R (PLL_R)
dividers both divide frequency down while the multiplier (MULT) multiplies frequency up. The purposes of adding
a multiplier is to reduce integer boundary spurs or to increase the phase detector frequency. Note that the
multiplier cannot be used if the OSCin doubler is used. The phase detector frequency, fPD, is calculated as
follows:
fPD = fOSC × OSC_2X × MULT / (PLL_R_PRE × PLL_R)
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Feature Description (continued)
7.3.2.1 OSCin Doubler (OSC_2X)
The OSCin doubler allows one to double the input reference frequency up to 400 MHz. This doubler adds
minimal noise and is useful for raising the phase detector frequency for better phase noise and also to avoid
spurs. When the phase-detector frequency is increased, the flat portion of the PLL phase noise improves.
-90
-95
Phase Noise (dBc/Hz)
-100
-105
-110
-115
-120
1.E+03
1.E+04
1.E+05
1.E+06
Offset (Hz)
Doubler Disabled, Fpd=100 MHz
Doubler Enabled, Fpd=200 MHz
Figure 18. Benefit of Using the OSC_2X Doubler at 14 GHz
7.3.2.2 Pre-R Divider (PLL_R_PRE)
The pre-R divider is useful for reducing the input frequency so that the programmable multiplier (MULT) can be
used or to help meet the maximum 250 MHz input frequency limitation to the PLL-R divider. Otherwise, it does
not have to be used.
7.3.2.3 Programmable Multiplier (MULT)
The MULT is useful for shifting the phase-detector frequency to avoid integer boundary spurs. The multiplier
allows a multiplication of 3, 4, 5, 6, or 7. Be aware that unlike the doubler, the programmable multiplier degrades
the PLL figure of merit; however, this only would matter for a clean reference and if the loop bandwidth was wide.
7.3.2.4 Post-R Divider (PLL_R)
The post-R divider can be used to further divide down the frequency to the phase detector frequency. When it is
used (PLL_R > 1), the input frequency to this divider is limited to 250 MHz.
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Feature Description (continued)
7.3.3 PLL Phase Detector and Charge Pump
The phase detector compares the outputs of the Post-R divider and N divider and generates a correction current
corresponding to the phase error until the two signals are aligned in phase. This charge-pump current is software
programmable to many different levels, allowing modification of the closed loop bandwidth of the PLL. See
application section on phase noise due to the charge pump.
7.3.4 N Divider and Fractional Circuitry
The N divider includes fractional compensation and can achieve any fractional denominator from 1 to (232 – 1).
The integer portion of N is the whole part of the N divider value, and the fractional portion, Nfrac = NUM / DEN, is
the remaining fraction. In general, the total N divider value is determined by N + NUM / DEN. The N, NUM and
DEN are software programmable. The higher the denominator, the finer the resolution step of the output. For
example, even when using fPD = 200 MHz, the output can increment in steps of 200 MHz / 232 = 0.047 Hz.
Equation 2 shows the relationship between the phase detector and VCO frequencies. Note that in SYNC mode,
there is an extra divider that is not shown in Equation 2.
NUM ·
§
fVCO fpd u ¨ N
DEN ¸¹
©
(2)
The sigma-delta modulator that controls this fractional division is also programmable from integer mode to fourth
order. To make the fractional spurs consistent, the modulator is reset any time that the R0 register is
programmed.
The N divider has minimum value restrictions based on the modulator order and VCO frequency. Furthermore,
the PFD_DLY_SEL bit must be programmed in accordance to the Table 2.
Table 2. Minimum N Divider Restrictions
FRAC_ORDER
fVCO (MHz)
MINIMUM N
PFD_DLY_SEL
≤ 12500
28
1
> 12500
32
2
≤ 10000
28
1
10000-12500
32
2
0
1
2
3
4
>12250
36
3
≤ 10000
32
2
>10000
36
3
≤ 10000
36
3
>10000
40
4
≤ 10000
44
5
>10000
48
6
7.3.5 MUXout Pin
The MUXout pin can be used to readback programmable states of the device or for lock detect.
Table 3. MUXout Pin Configurations
MUXOUT_SEL
24
FUNCTION
0
Readback
1
Lock Detect
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7.3.5.1 Lock Detect
The MUXout pin can be configured for lock detect done in by reading back the rb_LD_VTUNE field or using the
pin as shown in the Table 4.
Table 4. Configuring the MUXout Pin for Lock Detect
FIELD
PROGRAMMING
DESCRIPTION
LD_TYPE
0 = VCO Calibration Status
1 = Vtune
This determines if the lock detect is based on the VCO tuning voltage or at the VCO
calibration.
LD_DLY
0 to 65535
Only valid for Vtune lock detect. This is a delay in state machine cycles. The state
machine clock frequency is equal to fOSC/CAL_CLK_DIV
OUT_MUTE
0 = Disabled
1 = Enabled
Turns off outputs when lock detect is low.
VCO calibration status lock detect works by indicating a low signal whenever the VCO is calibrating or the
LD_DLY counter is running.
Vtune lock detect works by checking the Vtune voltage. Whenever the Vtune voltage is within an acceptable
range and the VCO is not calibrating, then Vtune lock detect is high.
7.3.5.2 Readback
The MUXout pin can be configured for to read back useful information from the device. Common uses for
readback are:
1. Read back registers to ensure that they have been programmed to the correct value.
2. Read back the lock detect status to determine if the PLL is in lock.
3. Read back VCO calibration information so that it can be used to improve the lock time.
4. Read back information to help troubleshoot.
VCO calibration status lock detect works by indicating a low signal whenever the VCO is calibrating or the
LD_DLY counter is running. The delay from the LD_DLY added to the true VCO calibration time (tVCOCAL) so it
can be used to account for the analog lock time of the PLL.
Vtune lock detect works by checking the Vtune voltage. Whenever the Vtune voltage is within an acceptable
range and the VCO is not calibrating, then Vtune lock detect is high.
7.3.6 VCO (Voltage Controlled Oscillator)
The LMX2594 includes a fully integrated VCO. The VCO takes the voltage from the loop filter and converts this
into a frequency. The VCO frequency is related to the other frequencies and as follows:
fVCO = fPD × N divider
(3)
7.3.6.1 VCO Calibration
To reduce the VCO tuning gain and therefore improve the VCO phase-noise performance, the VCO frequency
range is divided into several different frequency bands. The entire range, 7.5 to 15 GHz, covers an octave that
allows the divider to take care of frequencies below the lower bound. This creates the need for frequency
calibration to determine the correct frequency band given a desired output frequency. The frequency calibration
routine is activated any time that the R0 register is programmed with the FCAL_EN = 1. It is important that a
valid OSCin signal must present before VCO calibration begins.
The VCO also has an internal amplitude calibration algorithm to optimize the phase noise which is also activated
any time the R0 register is programmed.
The optimum internal settings for this are temperature dependent. If the temperature is allowed to drift too much
without being re-calibrated, some minor phase noise degradation could result. The maximum allowable drift for
continuous lock, ΔTCL, is stated in the electrical specifications. For this device, a number of 125°C means the
device never loses lock if the device is operated under recommended operating conditions.
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The LMX2594 allows the user to assist the VCO calibration. In general, there are three kinds of assistance, as
shown in Table 5:
Table 5. Assisting the VCO Calibration Speed
ASSISTANCE LEVEL
No assist
Partial assist
DESCRIPTION
PROGRAMMABLE SETTINGS
User does nothing to improve VCO calibration speed.
QUICK_RECAL_EN=0
Upon every frequency change, before the FCAL_EN bit is checked, the
user provides the initial starting point for the VCO core (VCO_SEL), band
QUICK_RECAL_EN=0
(VCO_CAPCTRL_STRT), and amplitude (VCO_DACISET_STRT) based on
Table 6.
Upon initialization of the device, user enables QUICK_RECAL_EN bit.
Close Frequency Assist The VCO uses the current VCO_CAPCTRL and VCO_AMPCAL settings as
the initial starting point.
Full assist
The user forces the VCO core (VCO_SEL), amplitude settings
(VCO_DACISET), and frequency band (VCO_CAPCTRL) and manually
sets the value.
QUICK_RECAL_EN=1
VCO_SEL_FORCE=1
VCO_DACISET_FORCE=1
VCO_CAPCTRL_FORCE=1
To do the partial assist for the VCO calibration, follow this procedure:
1. Determine VCO Core
Find a VCO Core that includes the desired VCO frequency. If at the boundary of two cores, choose based
on phase noise or performance.
2. Calculate the VCO CapCode as follows
VCO_CAPCTRL_STRT = round (CCoreMin – (CCoreMin – CCoreMax) × (fVCO – fCoreMin) / (fCoreMax – fCoreMin))
3. Get the AMPCal Setting from the table
VCO_AMPCAL = round (ACoreMin + (ACoreMax – ACoreMin) × (fVCO – fCoreMin)/(fCoreMax – fCoreMin))
Table 6. VCO Core Ranges
VCO Core
fCoreMin
fCoreMax
CCoreMin
CCoreMax
ACoreMin
ACoreMax
VCO 1
7500
8600
164
12
299
240
VCO 2
8600
9800
165
16
356
247
VCO 3
9800
10800
158
19
324
224
VCO 4
10800
12000
140
0
383
244
VCO 5
12000
12900
183
36
205
146
VCO 6
12900
13900
155
6
242
163
VCO 7
13900
15000
175
19
323
244
SPACE
NOTE
In the range of 11900 to 12100 MHz, VCO assistance cannot be used, and the settings
must be VCO_SEL = 4, VCO_DACISET_STRT = 300, and VCO_CAPCTRL_STRT = 1.
Outside this range, in the partial assist for the VCO calibration, the VCO calibration is run.
This means that if the settings are incorrect, the VCO still locks with the correct settings;
the only consequence is that the calibration time might be a little longer. The closer the
calibration settings are to the true final settings, the faster the VCO calibration will be.
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7.3.6.2 Determining the VCO Gain
The VCO gain varies between the seven cores and is the lowest at the lowest end of the band and highest at the
highest end of each band. For a more accurate estimation, use Table 7:
Table 7. VCO Gain
f1
f2
Kvco1
Kvco2
7500
8600
79
113
8600
9800
81
99
9800
10800
88
130
10800
12000
182
225
12000
12900
195
250
12900
13900
250
250
Based in this table, the VCO gain can be estimated for an arbitrary VCO frequency of fVCO as:
Kvco = Kvco1 + (Kvco2-Kvco1) × (fVCO – f1) / (f2 – f1)
(4)
7.3.7 Channel Divider
To go below the VCO lower bound of 7.5 GHz, the channel divider can be used. The channel divider consists of
four segments, and the total division value is equal to the multiplication of them. Therefore, not all values are
valid.
VCO
1/2
Divide by
2 or 3
Divide by
2,4,6,8
Divide by
2,4,6,8,16
MUX
RFoutA
MUX
RFoutB
MUX
Figure 19. Channel Divider
When the channel divider is used, there are limitations on the values. Table 8 shows how these values are
implemented and which segments are used.
Table 8. Channel Divider Segments
EQUIVALENT
DIVISION
VALUE
FREQUENCY
LIMITATION
2
4
None
6
OutMin (MHz)
OutMax (MHz)
CHDIV[4:0]
SEG0
SEG1
SEG2
SEG3
3750
7500
0
2
1
1
1
1875
3750
1
2
2
1
1
1250
2500
2
2
3
1
1
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Table 8. Channel Divider Segments (continued)
EQUIVALENT
DIVISION
VALUE
FREQUENCY
LIMITATION
OutMin (MHz)
OutMax (MHz)
CHDIV[4:0]
SEG0
SEG1
SEG2
SEG3
8
937.5
1250
3
2
2
2
1
12
625
833.333
4
2
3
2
1
16
468.75
625
5
2
2
4
1
24
312.5
416.667
6
2
2
6
1
32
234.375
312.5
7
2
2
8
1
48
125.25
208.333
8
2
3
8
1
64
117.1875
156.25
9
2
2
8
2
104.157
138.889
10
2
3
6
2
96
78.125
104.167
11
2
3
8
2
128
58.594
78.125
12
2
2
8
4
192
39.063
52.083
13
2
2
8
6
256
29.297
39.063
14
2
2
8
8
384
19.531
26.042
15
2
3
8
8
512
14.648
19.531
16
2
2
8
16
9.766
13.021
17
2
3
8
16
n/a
n/a
18-31
n/a
n/a
n/a
n/a
72
fVCO ≤ 10 GHz
768
Invalid
n/a
The channel divider is powered up whenever an output (OUTx_MUX) is selected to the channel divider or
SysRef, regardless of whether it is powered down or not. When an output is not used, TI recommends selecting
the VCO output to ensure that the channel divider is not unnecessarily powered up.
Table 9. Channel Divider
OUTA MUX
OUTB MUX
CHANNEL DIVIDER
Channel Divider
X
Powered up
X
Channel Divider or SYSREF
All Other Cases
Powered up
Powered down
7.3.8 Output Buffer
The RF output buffer type is open collector so it requires an external pullup to Vcc. This component may be a 50Ω resistor to give a nice 50-Ω output impedance, or an inductor. The inductor has poor output impedance, but
allows higher output power. The output power can be programmed to various levels or disabled while still
keeping the PLL in lock. If using a resistor, limit OUTx_PWR setting to 40; higher than this tends to actually
reduce power.
7.3.9 Powerdown Modes
The LMX2594 can be powered up and down using the CE pin or the POWERDOWN bit. When the device comes
out of the powered down state, either by resuming the POWERDOWN bit to zero or by pulling back CE pin HIGH
(if it was powered down by CE pin), register R0 must be programmed with FCAL_EN high again to re-calibrate
the device.
7.3.10 Phase Synchronization
7.3.10.1 General Concept
The SYNC pin allows one to synchronize the LMX2594 such that the delay from the rising edge of the OSCin
signal to the output signal is deterministic. Initially, the devices are locked to the input, but are not synchronized.
The user sends a synchronization pulse that is reclocked to the next rising edge of the OSCin pulse. After a
given time, t1, the phase relationship from OSCin to fOUT will be deterministic. This time is dominated by the sum
of the VCO calibration time, the analog setting time of the PLL loop, and the MASH_RST_CNT if used in
fractional mode.
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...
Device 1
SYNC
...
Device 2
...
...
fOSC
t2
t1
Figure 20. Devices Are Now Synchronized to OSCin Signal
When the SYNC feature is enabled, part of the channel divide is included in the feedback path.
Table 10. Included Divide
OUTA_MUX / OUTB_MUX
CHANNEL DIVIDER
INCLUDED DIVIDE
Neither one has the channel divider or
SysRef selected
x
None
Divisible by 3, but NOT 24 or 192
SEG0 × SEG1 = 6
All other values
SEG0 × SEG1 = 4
At least one is selecting the channel divider
or SYSREF
External loop filter
OSCin
Doubler
Pre-R
Divider
XM
R
Divider
Charge
Pump
I
MUX
RFoutA
MUX
RFoutB
SEG0
SEG3
SEG1
SEG4
N Divider
Figure 21. Phase SYNC Diagram
7.3.10.2 Categories of Applications for SYNC
The requirements for SYNC depend on certain setup conditions. In cases that the SYNC is not timing critical, it
can be done through software by toggling the VCO_PHASE_SYNC bit from 0 to 1. When it is timing critical, then
it must be done through the pin and the setup and hold times for the OSCin pin are critical. The Figure 22 gives
the different categories.
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Start
NO
CHDIV <512
?
CHDIV = 1,2,4,6
This means the channel divider after the
VCO is either bypassed,2,4, or 6. In this
case, SYNC mode will put it in the loop.
YES
CHDIV<512
This means the Channel divider
after the VCO is less than 512
M=1
M is the product of any input
path multiplication due to the
OSC_2X bit and MULT word. If
neither of these are used,
M=1.
NO
CHDIV = 1,2,4,6
?
NO
Category 4
Device can NOT be reliably
used in SYNC mode
YES
YES
M=1
?
NO
fOUT%(D| (OSC)=0
Category 3
x SYNC Required
x SYNC Timing Critical
x Limitations on fOSC
fOUT % (D| (OSC)= 0
M is the product of any
input multiplication. This
requirement is testing if the
output frequency is a
multiple of the highest
frequency in the input
path.
YES
NO
YES
fOUT % fOSC = 0
This means that the output
fOUT % fOSC = 0
?
frequency (fOUT) is an integer
multiple of the input frequency (fOSC)
CHDIV = 1,2,4, 6
?
NO
Category 2
x SYNC Required
x SYNC Timing NOT critical
x No limitations on fOSC
Integer Mode
This is asking if the device is
in integer mode, which
would mean the fractional
numerator is zero.
YES
CHDIV = 1,2,4,6
This means the channel
divider after the VCO is either
bypassed,2,4, or 6. In this
case, SYNC mode will put it in
the loop.
YES
NO
CHDIV=1?
Integer Mode
?
NO
Category 1
x SYNC Mode Required
x No Software/Pin SYNC Pulse required
Category 1
x SYNC Mode Not required at all
x No limitations on fOSC
Figure 22. Determining the SYNC Category
30
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7.3.10.3 Procedure for Using SYNC
This procedure must be used to put the device in SYNC mode.
1. Use the flowchart to determine the SYNC category.
2. Make determinations for OSCin and using SYNC based on the category
(a) If Category 4, SYNC cannot be performed in this setup.
(b) If category 3, ensure that the maximum fOSC frequency for SYNC is not violated and there are hardware
accommodations to use the SYNC pin.
3. If the channel divide is used, determine the included channel divide value which will be 2 × SEG0 of the
channel divide:
(a) If neither OUTA_MUX nor OUTB_MUX is selected to channel divider, then the included divide is one.
(b) If one of them is, then the included channel divide value will be 2 × SEG0.
4. If not done already, divide the N divider and fractional values by the included channel divide to account for
the included channel divide.
5. Program the device with the VCO_PHASE_SYNC = 1. Note that this does not count as applying a SYNC to
device (for category 2).
6. Apply the SYNC, if required
(a) If category 2, VCO_PHASE_SYNC can be toggled from 0 to 1. Alternatively, a rising edge can be sent to
the SYNC pin and the timing of this is not critical.
(b) If category 3, the SYNC pin must be used, and the timing must be away from the rising edge of the
OSCin signal.
7.3.10.4 SYNC Input Pin
The SYNC input pin can be driven either in CMOS or LVDS mode. However, if not using SYNC mode
(VCO_PHASE_SYNC = 0), then the INPIN_IGNORE bit must be set to one, otherwise it causes issues with lock
detect. If the pin is desired for to be used and VCO_PHASE_SYNC=1, then set INPIN_IGNORE = 0. LVDS or
CMOS mode may be used. LVDS works to 250 mVPP, but is not ensured in production.
7.3.11 Phase Adjust
The LMX2594 can use the sigma-delta modulator to adjust the output signal phase with respect to the input
reference. The phase shift every time you write the value of MASH SEED is:
Phase shift in degrees = 360 × ( MASH_SEED / PLL_DEN) × ( IncludedDivide/CHDIV )
(5)
Example:
Mash seed = 1
Denominator = 12
Channel divider = 16
Phase shift ( VCO_PHASE_SYNC=1) = 360 × (1/12) × (1/16) = 1.875 degrees
Phase Shift (VCO_PHASE_SYNC=1) = 360 × (1/12) × (4/16) = 7.5 degrees
Phase shift can be done with a FRAC_NUM=0, but FRAC_ORDER must be greater than zero. In the case of one
output being set to the VCO and the other output unused, the unused output can powered down but directed to
the channel divider to put part of this in the loop, which can sometimes be used to create a fraction. For the
phase adjust, the condition PLL_DEN > PLL_NUM + MASH_SEED must be satisfied.
7.3.12 Ramping Function
The LMX2594 supports the ability to make ramping waveforms using manual mode or automatic mode. In
manual mode, the user defines a step and uses the RampClk and RampDir pins to create the ramp. In automatic
mode, the user sets up the ramp with up to two linear segments in advance and the device automatically creates
this ramp. Table 11 fields apply in both automatic mode and manual pin mode.
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Table 11. Ramping Field Descriptions
FIELD
PROGRAMMING
DESCRIPTION
GENERAL COMMANDS
0 = Disabled
1 = Enabled
RAMP_EN must be 1 for any ramping functions to work.
0 = Automatic ramping mode
1 = Manual pin ramping mode
In automatic ramping mode, the ramping is automatic and the
clock is based on the phase detector. In manual pin ramping
mode, the clock is based on rising edges on the RampCLk
pin.
RAMPx_INC
0 to 230 – 1
This is the amount the fractional numerator is increased for
each phase detector cycle in the ramp.
RAMPx_DLY
0 to 65535
RAMP_EN
RAMP_MANUAL
This is the length of the ramp in phase detector cycles.
DEALING WITH VCO CALIBRATION
0 to ± 232
Whenever the fractional numerator changes this much (either
positive or negative) because the VCO was last calibrated,
the VCO is forced to recalibrate.
RAMP_TRIG_CAL
0 = Disabled
1 = Enabled
When enabled, the VCO is forced to re-calibrate at the
beginning each ramp. This only applies in automatic ramping
mode.
PLL_DEN
4294967295
In ramping mode, the denominator must be fixed to this
forced value of 232 – 1. However, the effective denominator in
ramping mode is 224.
RAMP_THRESH
LD_DLY
0
This must be zero to avoid interfering with calibration.
RAMP LIMITS
RAMP_LIMIT_LOW
RAMP_LIMIT_HIGH
2’s complement of the total value of the ramp low and high
limits can never go beyond. If this value is exceeded, then the
frequency is limited.
0 to 231
Table 12. General Restrictions for Ramping
RULE
Phase Detector
Frequency
RESTRICTION
EXPLANATION
fOSC / 2CAL_CLK_DIV ≤ fPD≤ 125
MHz
Minimum Phase Detector Frequency when Ramping
The phase detector frequency cannot be less than the state machine clock
frequency. The state machine clock frequency is calculated from expression
on the left-hand side of the inequality. This is satisfied provided there is no
division in the input path. However, if the PLL R divider is used, it is
necessary to adjust CAL_CLK_DIV to satisfy this constraint. Also, this implies
a maximum total division in the input path of 8.
Maximum Phase Detector Frequency
TI recommends that phase-detector frequency be less or equal than 125 MHz
because if the phase detector frequency is too high, it can lead to distortion in
the ramp. Higher phase-detector frequency frequencies may be possible, but
this distortion is application specific.
7.3.12.1 Manual Pin Ramping
Manual pin ramping is enabled by setting RAMP_EN = 1 and RAMP_MODE = 1. In this mode, the ramp is
clocked by rising edges applied to the RampCLk pin, and the RampDir pin controls the size of the change. If a
rising edge is seen on the RampCLk pin while the VCO is calibrating, then this rising edge is ignored. The
frequency for the RampCLK must be limited to a frequency of 250 kHz or less, and the rising edge of the
RampDir signal must be targeted to the falling edge of the RampCLK pin.
Table 13. RAMP_INC
32
RampDir PIN
STEP SIZE
Low
Add RAMP0_INC
High
Add RAMP1_INC
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7.3.12.1.1 Manual Pin Ramping Example
In this ramping example, assume that we want to use the pins for UP/Down control of the ramp for 10 MHz steps
and the phase detector is 100 MHz.
Table 14. Step Ramping Example
FIELD
PROGRAMMING
RAMP_EN
DESCRIPTION
1 = Enabled
RAMP_MANUAL
1 = Manual pin ramping mode
RAMP0_INC
1677722
(10 MHz )/ (100 MHz) × 16777216 = 1677722
2’s complement = 1677722
RAMP1_INC
1072064102
(–10 MHz )/ (100 MHz) × 16777216 = –1677722
2’s complement = 2^30 – 1677722 = 1072064102
1
Re-calibrate at every clock cycle
Output Frequency
RAMP_TRIG_CAL
RampClk/Trig1 Pin
time
RampDir/Trig2 Pin
time
time
Figure 23. Step Ramping Example
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7.3.12.2 Automatic Ramping
Automatic ramping is enabled when RAMP_EN=1 and RAMP_MODE = 0. The action of programming FCAL = 1
starts the ramping. In this mode, there are two ramps that one can set the length and frequency change. In
addition to this, there are ramp limits that can be used to create more complicated waveforms.
Automatic ramping can really be divided into two classes depending on if the VCO must calibrate in the middle of
the ramping waveform or not. If the VCO can go the entire range without calibrating, this is calibration-free
ramping, which is shown in Typical Characteristics. Note that this range is less at hot temperatures and for lower
frequency VCOs. This range is not ensured, so margin must be built into the design.
For waveforms that are NOT calibration free, the slew rate of the ramp must be kept less than 250 kHz/µs. Also,
for all automatic ramping waveforms, be aware that there is a very small phase disturbance as the VCO crosses
over the integer boundary, so one might consider using the input multiplier to avoid these or timing the VCO
calibrations at integer boundaries.
Table 15. Automatic Ramping Field Descriptions
FIELD
PROGRAMMING
DESCRIPTION
RAMP_DLY
0 = One clock cycle
1 = Two clock cycles
Normally the ramp clock is equal to the phase detector frequency.
When this feature is enabled, it reduces the ramp clock by a factor of
2.
RAMP0_LEN
RAMP1_LEN
0 to 65535
This is the length of the ramp in clock cycles. Note that the time that
the VCO is calibrating is added to this time.
RAMP0_INC
RAMP1_INC
0 to 230
2’s complement of the value for the ramp increment.
0 = RAMP0
1 = RAMP1
Defines which ramp comes after the current ramp.
0
1
2
3
Determines what triggers the action of the next ramp occurring.
RAMP0_NEXT
RAMP1_NEXT
RAMP0_NEXT_TRIG
RAMP1_NEXT_TRIG
RAMP_TRIG_A
RAMP_TRIG_B
RAMP0_RST
RAMP1_RST
RAMP_BURST_COUNT
RAMP_BURST_TRIG
= Timeout counter
= Trigger A
= Trigger B
= Reserved
0 = Disabled
1 = RampCLk rising edge
2 = RampDir rising edge
4 = Always triggered
9 = RampCLk falling edge
10 = RampDir falling edge
All other States = invalid
This field defines what the ramp trigger is.
0 = Disabled
1 = Enabled
Enabling this bit causes the ramp to reset to the original value when
the ramping started. This is useful for roundoff errors.
0 to 8191
This is the number the ramping pattern repeats and only applies for a
terminating ramping pattern.
0 = Ramp Transition
1 = Trigger A
2 = Trigger B
This defines what causes the RAMP_COUNT to increment.
3 = Reserved
34
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7.3.12.2.1 Automatic Ramping Example (Triangle Wave)
Suppose user wants to generate a sawtooth ramp that goes from 8 to 10 GHz in 2 ms (including calibration
breaks) with a phase-detector frequency of 50 MHz. Divide this into segments of 50 MHz where the VCO ramps
for 25 µs, then calibrates for 25 µs, for a total of 50 µs. There would therefore be 40 such segments which span
over a 2-GHz range and would take 2 ms, including calibration time.
Table 16. Sawtooth Ramping Example
FIELD
RAMP_EN
RAMP_MANUAL
RAMP_TRIG_CAL
RAMP_THRESH
PROGRAMMING
DESCRIPTION
1 = Enabled
0 = Automatic ramping
mode
0 = Disabled
50 MHz / 50 MHz × 224 = 16777216
8388608
RAMP_DLY
0 = 1 clock cycle
RAMPx_LEN
13422
1000 µs × 50 MHz = 50000
RAMP0_INC
13422
(2000 MHz) / (50 MHz) × 224 / 50000 = 13422
RAMP1_INC
1073740146
(–2000 MHz) / (50 MHz) × 224 / 50000 = –13422
2’s complement = 230 – 13422 = 1073728402
RAMP0_NEXT
1 = RAMP1
RAMP1_NEXT
0 = RAMP0
RAMPx_NEXT_TRIG
0 = Timeout counter
RAMP_TRIG_x
0 = Disabled
RAMP0_RST
1 = Enabled
Not necessary, but good practice to reset.
RAMP1_RST
0 = Disabled
Do not reset this, or ramp does not work.
RAMP_BURST_COUNT
RAMP_BURST_TRIG
0
0 = Ramp Transition
10 GHz
RA
MP
RA
0
MP
1
0
MP
RA
8 GHz
1 ms
time
2 ms
Figure 24. Triangle Waveform Example
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7.3.13 SYSREF
The LMX2594 can used to a SYSREF output signal that synchronized to the output with a programmable delay.
This output can be a single pulse, series of pulse, or a continuous stream of pulses. To use the SYSREF
capability, the PLL must be in SYNC mode with VCO_PHASE_SYNC = 1.
fVCO
To Phase
Detector
fOUT
MUX
Rest of Channel
Divider
Part of Channel
Divider
(SYSREF_DIV_CH)
RFoutA
N Divider
fPRESYSREF
Divider
(SYSREF_DIV_PRE)
Divider
(SYSREF_DIV)
fSYSREF
fSYSREF
RFoutB
Delay Circuit
Figure 25. SYSREF Setup
As Figure 25 shows, the SYSREF feature shares parts of the channel divide and puts a pre-divider in front of the
N divider; this must be taken into consideration when using the SYSREF feature.
When configured for this mode, a rising edge is sent to the SysRefReq pin, which causes the device to output
either a single pulse or a series of pulses to the RFoutB pins. These pulses are synchronous with the RFoutA
signal with an adjustable delay.
Table 17. SYSREF Setup
PARAMETER
MIN
MAX
UNIT
fVCO
7.5
15
GHz
fINTERPOLATOR
0.8
1.5
GHz
SYSREF_DIV_CH (Part of channel divider)
TYP
2, 4, or 6
SYSREF_DIV_PRE
1, 2, or 4
SYSREF_DIV
1 to 2047, but maybe not all values can be used
fINTERPOLATOR
fPRESYSREF = fVCO /(SYSREF_DIV_CH ×
SYSREF_DIV_PRE)
fSYSREF
fSYSREF = fINTERPOLATOR / (2 × SYSREF_DIV)
Delay step size
9
Pulses for pulsed mode (SYSREF_PULSE_CNT)
0
ps
15
n/a
The delay can be programmed using the JESD_DAC1_CTRL, JESD_DAC2_CTRL, JESD_DAC3_CTRL, and
JESD_DAC4_CTRL words. By concatenating these words into a larger word called "SysRefPhaseShift", the
relative delay can be found. The sum of these words should always be 63.
36
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Table 18. SysRef Delay
SysRef
DELAY
DELAY
JESD_DAC1
JESD_DAC2
JESD_DAC3
JESD_DAC4
0
Minimum
36
27
0
0
0
0
36
0
63
0
0
37
62
1
0
0
99
0
0
63
0
100
0
0
62
1
161
0
0
1
62
162
0
0
0
63
163
1
0
0
62
224
63
0
0
0
225
62
1
0
0
...
...
...
247
Maximum
41
22
0
0
> 247
Invalid
Invalid
Invalid
Invalid
Invalid
7.3.13.1 Programmable Fields
Table 19 has the programmable fields for the SYSREF functionality.
Table 19. SYSREF Programming Fields
FIELD
SYSREF_EN
PROGRAMMING
0 = Disabled 1 = enabled
DEFAULT
0
DESCRIPTION
Enables the SYSREF mode
SYSREF_DIV_PRE
1: DIV1
2: DIV2
4: DIV4
Other states: invalid
The output of this divider is the fPRESYSREF.
SYSREF_REPEAT
0 = Generator
1 = Repeater
0
In generator mode, the device creates a
series of SYSREF pulses. In repeater mode,
SYSREF pulses are generated with the
SysRefReq pin.
0 = Continuous mode
1 = Pulsed mode
0
Continuous mode continuously makes
SYSREF pulses, where pulsed mode makes
a series of SYSREF_PULSE_CNT pulses
0 to 15
4
In the case of using pulsed mode, this is the
number of pulses. Setting this to zero is an
allowable, but not practical state.
170 to 2047
0
The SYSREF frequency is at the VCO
frequency divided by this value.
SYSREF_PULSE
SYSREF_PULSE_CNT
SYSREF_DIV
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7.3.13.2 Input and Output Pin Formats
7.3.13.2.1 Input Format for SYNC and SYSREF Pins
These pins are single-ended but a differential signal can be converted to drive them. In the LVDS mode, if the
INPIN_FMT is set to LVDS mode, then the bias level can be adjusted with INPIN_LVL and the hysteresis can be
adjusted with INPIN_HYST.
VMIN
SYNC
LMX2594
VMAX
Figure 26. Driving SYNC/SYSREF with Differential Signal
7.3.13.2.2 SYSREF Output Format
The SYSREF output comes in differential format through RFoutB. This will have a minimum voltage of about 2.3
V and a maximum of 3.3 V. If DC coupling cannot be used, there are two strategies for AC coupling.
3.3 V
SysRefOutP
Data
Converter
SysRefOutN
LMX2594
3.3 V
Figure 27. SYSREF Output
1. Send a series of pulses to establish a DC-bias level across the AC-coupling capacitor.
2. Establish a bias voltage at the data converter that is below the threshold voltage by using a resistive divider.
7.3.13.3 Examples
The SYSREF can be used in a repeater mode, which just echos the input, after being reclocked to OSCin and
then RFout, or it can be used in a repeater. In either mode, there is a phase adjustment with resolution of 1/16 of
the output phase up to a maximum of 1 ns. In repeater mode, it can repeat 1,2,4,8, or infinite (continuous)
pulses. The frequency for repeater mode is equal to the RFout frequency divided by the SYSREF divider.
38
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RFoutAP
SYNC
RFoutAN
¥
OSCinP
OSCinN
¥
t1
LMX2594
t1
RFoutBP/SYSREFoutP
SysRefReq
RFoutBP/SYSREFoutN
RFoutAP
SYNC
RFoutAN
OSCinN
¥
¥
OSCinP
LMX2594
t2
t2
RFoutBP/SYSREFoutP
SysRefReq
RFoutBP/SYSREFoutN
Figure 28. SYSREF Out In Repeater Mode
RFoutAP
SYNC
RFoutAN
¥
OSCinP
OSCinN
¥
t
LMX2594
RFoutBP/SYSREFoutP
SysRefReq
RFoutBP/SYSREFoutN
RFoutAP
SYNC
RFoutAN
¥
¥
OSCinP
OSCinN
LMX2594
t
RFoutBP/SYSREFoutP
SysRefReq
RFoutBP/SYSREFoutN
Figure 29. Figure 1. SYSREF Out In Pulsed/Continuous Mode
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7.3.13.4 SYSREF Procedure
To
1.
2.
3.
use SYSREF, do the these steps:
Put the device in SYNC mode using the procedure already outlined.
Figure out the included channel divide the same way it is done for SYNC mode.
Calculate the SYSREF_DIV_PRE value such that the interpolator frequency (fINTERPOLATOR) is in the range of
800 to 1500 MHz. fINTERPOLATOR = fVCO/IncludedDivide/SYSREF_DIV_PRE
4. If using master mode (SYSREF_REPEAT=0), ensure SysRefReq pin is high, ensure the SysRefReq pin is
high.
5. If using repeater mode (SYSREF_REPEAT=1), set up the pulse count if desired. Pulses are created by
toggling the SysRefReq pin.
6. Adjust the delay between the RFoutA and RFoutB signal using the JESD_DACx_CTL fields.
7.3.14 SysRefReq Pin
The SysRefReq pin can be used in CMOS all the time, or LVDS mode is also optional if SYSREF_REPEAT = 1.
LVDS mode cannot be used in master mode.
7.4 Device Functional Modes
Although there is a vast number of ways to configure this device, there is really only one functional.
Table 20. Device Functional Modes
MODE
DESCRIPTION
RESET
Registers are held in their reset state. This device does have a
power on reset, but it is good practice to also do a software reset if
there is any possibility of noise on the programming lines, especially
if there is sharing with other devices. Also realize that there are
registers not disclosed in the data sheet that are reset as well.
RESET = 1, POWERDOWN = 0
Device is powered down.
POWERDOWN = 1
or CE Pin = Low
POWERDOWN
Normal operating mode
SYNC mode
SYSREF mode
40
SOFTWARE SETTINGS
This is used with at least one output on as a frequency synthesizer.
This is used where part of the channel divider is in the feedback path
VCO_PHASE_SYNC = 1
to ensure deterministic phase.
In this mode, RFoutB is used to generate pulses for SYSREF.
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VCO_PHASE_SYNC =1,
SYSREF_EN = 1
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7.5 Programming
The LMX2594 is programmed using 24-bit shift registers. The shift register consists of a R/W bit (MSB), followed
by a 7-bit address field and a 16-bit data field. For the R/W bit, 0 is for write, and 1 is for read. The address field
ADDRESS[6:0] is used to decode the internal register address. The remaining 16 bits form the data field
DATA[15:0]. While CSB is low, serial data is clocked into the shift register upon the rising edge of clock (data is
programmed MSB first). When CSB goes high, data is transferred from the data field into the selected register
bank. See Figure 1 for timing details.
7.5.1 Recommended Initial Power-Up Sequence
For the most reliable programming, TI recommends this procedure:
1. Apply power to device.
2. Program RESET = 1 to reset registers.
3. Program RESET = 0 to remove reset.
4. Program registers as shown in the register map in REVERSE order from highest to lowest.
5. Program register R0 one additional time with FCAL_EN = 1 to ensure that the VCO calibration runs from a
stable state.
7.5.2 Recommended Sequence for Changing Frequencies
The recommended sequence for changing frequencies is as follows:
1. Change the N divider value.
2. Program the PLL numerator and denominator.
3. Program FCAL_EN (R0[3]) = 1.
7.6 Register Maps and Descriptions
Note that for registers that have numbers, but defined programmable bits, it is necessary to program these
values just as shown in the register map. Registers must be programmed from highest to lowest (R0 Last)
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Table 21. Full Register Map
R/W
A6
A5
A4
A3
A2
A1
A0
D15
D14
D13
D12
D11
D10
D9
1
0
0
1
OUT
_MU
TE
D8
D7
D6
D5
D4
D3
D2
D1
D0
1
FCA
L
_EN
MUX
OUT
_LD_
SEL
RES
ET
POW
ERD
OWN
R0
0
0
0
0
0
0
0
0
RAMP
_EN
VCO
_PH
ASE
_SY
NC_
EN
R1
0
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
0
0
0
1
CAL_CLK_DIV
R2
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
R3
0
0
0
0
0
0
1
1
0
0
0
0
0
1
1
0
0
1
0
0
0
0
1
0
R4
0
0
0
0
0
1
0
0
0
0
0
0
1
0
1
0
0
1
0
0
0
0
1
1
R5
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
1
1
0
0
1
0
0
0
R6
0
0
0
0
0
1
1
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
1
0
0
OUT
_FO
RCE
0
0
0
0
0
0
1
0
1
1
0
0
1
0
1
0
VCO
_CA
PCT
RL_F
ORC
E
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
1
0
0
1
0
1
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
R7
0
0
0
0
0
1
1
1
FCAL_HPF
D_ADJ
FCAL_LPFD
_ADJ
R8
0
0
0
0
1
0
0
0
0
VCO
_DA
CISE
T_F
ORC
E
R9
0
0
0
0
1
0
0
1
0
0
0
OSC
_2X
R10
0
0
0
0
1
0
1
0
0
0
0
1
R11
0
0
0
0
1
0
1
1
0
0
0
0
R12
0
0
0
0
1
1
0
0
0
1
0
1
R13
0
0
0
0
1
1
0
1
0
1
0
0
0
0
0
0
0
R14
0
0
0
0
1
1
1
0
0
0
0
1
1
1
1
0
0
R15
0
0
0
0
1
1
1
1
0
0
0
0
0
1
1
0
0
R16
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
VCO_DACISET
R17
0
0
0
1
0
0
0
1
0
0
0
0
0
0
0
VCO_DACISET_STRT
R18
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
R19
0
0
0
1
0
0
1
1
0
0
1
0
0
1
1
1
R20
0
0
0
1
0
1
0
0
1
0
VCO
_SEL
_FO
RCE
0
0
0
1
0
0
1
0
0
0
R21
0
0
0
1
0
1
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
1
R22
0
0
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
42
MULT
PLL_R
PLL_R_PRE
VCO_SEL
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0
0
0
0
CPG
1
1
0
1
0
0
0
VCO_CAPCTRL
Copyright © 2017, Texas Instruments Incorporated
Product Folder Links: LMX2594
LMX2594
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SNAS696 – MARCH 2017
Table 21. Full Register Map (continued)
R/W
A6
A5
A4
A3
A2
A1
A0
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
R23
0
0
0
1
0
1
1
1
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
R24
0
0
0
1
1
0
0
0
0
0
0
0
0
1
1
1
0
0
0
1
1
0
1
0
R25
0
0
0
1
1
0
0
1
0
0
0
0
0
1
1
0
0
0
1
0
0
1
0
0
R26
0
0
0
1
1
0
1
0
0
0
0
0
1
1
0
1
1
0
1
1
0
0
0
0
R27
0
0
0
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
R28
0
0
0
1
1
1
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
0
0
0
R29
0
0
0
1
1
1
0
1
0
0
1
1
0
0
0
1
1
0
0
0
1
1
0
0
R30
0
0
0
1
1
1
1
0
0
0
1
1
0
0
0
1
1
0
0
0
1
1
0
0
R31
0
0
0
1
1
1
1
1
0
1
0
0
0
0
1
1
1
1
1
0
1
1
0
0
R32
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
1
0
0
1
1
R33
0
0
1
0
0
0
0
1
0
0
0
1
1
1
1
0
0
0
1
0
0
0
0
1
R34
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R35
0
0
1
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
R36
0
0
1
0
0
1
0
0
0
0
0
0
0
1
0
0
OUT
B_P
D
OUT
A_P
D
MAS
H_R
ESE
T_N
0
0
MASH_ORDER
0
1
1
PLL_N[18:16]
PLL_N
MASH_SEE
D_EN
R37
0
0
1
0
0
1
0
1
0
PFD_DLY_SEL
R38
0
0
1
0
0
1
1
0
R39
0
0
1
0
0
1
1
1
PLL_DEN[15:0]
R40
0
0
1
0
1
0
0
0
MASH_SEED[31:16]
R41
0
0
1
0
1
0
0
1
MASH_SEED[15:0]
R42
0
0
1
0
1
0
1
0
PLL_NUM[31:16]
R43
0
0
1
0
1
0
1
1
PLL_NUM[15:0]
PLL_DEN[31:16]
R44
0
0
1
0
1
1
0
0
0
0
OUTA_PWR
R45
0
0
1
0
1
1
0
1
1
1
0
R46
0
0
1
0
1
1
1
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
R47
0
0
1
0
1
1
1
1
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
R48
0
0
1
1
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
R49
0
0
1
1
0
0
0
1
0
1
0
0
0
0
0
1
1
0
0
0
0
0
0
0
R50
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R51
0
0
1
1
0
0
1
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
R52
0
0
1
1
0
1
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
R53
0
0
1
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
OUTA_MUX
OUT_ISET
OUTB_PWR
OUTB_MUX
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Table 21. Full Register Map (continued)
R/W
A6
A5
A4
A3
A2
A1
A0
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
R54
0
0
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R55
0
0
1
1
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R56
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R57
0
0
1
1
1
0
0
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
R58
0
0
1
1
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
R59
0
0
1
1
1
0
1
1
R60
0
0
1
1
1
1
0
0
R61
0
0
1
1
1
1
0
R62
0
0
1
1
1
1
R63
0
0
1
1
1
R64
0
1
0
0
0
R65
0
1
0
0
R66
0
1
0
R67
0
1
0
R68
0
1
R69
0
R70
0
0
0
0
0
0
0
0
LD_T
YPE
0
1
0
1
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
0
1
0
0
0
SYS
REF
_EN
SYS
REF
_RE
PEA
T
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
0
0
1
0
1
MASH_RST_COUNT[31:16]
1
0
0
0
1
1
0
MASH_RST_COUNT[15:0]
LD_DLY
R71
0
1
0
0
0
1
1
1
0
0
0
0
0
R72
0
1
0
0
1
0
0
0
0
0
0
0
0
R73
0
1
0
0
1
0
0
1
0
0
0
0
R74
0
1
0
0
1
0
1
0
SYSREF_PULSE_CNT
R75
0
1
0
0
1
0
1
1
0
0
0
0
1
R76
0
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
R77
0
1
0
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
RAM
P_T
HRE
SH[3
2]
0
QUIC
K_R
ECA
L_EN
0
0
0
0
SYSREF_DIV
JESD_DAC2_CTRL
JESD_DAC1_CTRL
JESD_DAC4_CTRL
JESD_DAC3_CTRL
CHDIV
R78
0
1
0
0
1
1
1
0
R79
0
1
0
0
1
1
1
1
RAMP_THRESH[31:16]
R80
0
1
0
1
0
0
0
0
RAMP_THRESH[15:0]
44
0
0
SYS
REF
SYSREF_DIV_PRE
_PUL
SE
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0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
VCO_CAPCTRL_STRT
1
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SNAS696 – MARCH 2017
Table 21. Full Register Map (continued)
R/W
A6
A5
A4
A3
A2
A1
A0
D15
0
D14
0
D10
0
D9
0
D8
D7
0
D6
1
0
1
0
0
0
1
R82
0
1
0
1
0
0
1
0
RAMP_LIMIT_HIGH[31:16]
R83
0
1
0
1
0
0
1
1
RAMP_LIMIT_HIGH[15:0]
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R85
0
1
0
1
0
1
0
1
RAMP_LIMIT_LOW[31:16]
R86
0
1
0
1
0
1
1
0
RAMP_LIMIT_LOW[15:0]
R87
0
1
0
1
0
1
1
1
0
0
0
0
0
0
0
0
R88
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
R89
0
1
0
1
1
0
0
1
0
0
0
0
0
0
0
R90
0
1
0
1
1
0
1
0
0
0
0
0
0
0
R91
0
1
0
1
1
0
1
1
0
0
0
0
0
R92
0
1
0
1
1
1
0
0
0
0
0
0
0
R93
0
1
0
1
1
1
0
1
0
0
0
0
R94
0
1
0
1
1
1
1
0
0
0
0
R95
0
1
0
1
1
1
1
1
0
0
0
0
0
0
R97
0
1
1
0
0
0
0
1
RAMP0_RS
T
R98
0
1
1
0
0
0
1
0
0
0
0
0
0
0
RAMP_BURST_COUNT
0
0
0
1
RAMP_TRIGB
RAMP_TRIGA
0
R99
0
1
1
0
0
0
1
1
RAMP0_INC[15:0]
R100
0
1
1
0
0
1
0
0
RAMP0_LEN
R101
0
1
1
0
0
1
0
1
0
0
R102
0
1
1
0
0
1
1
0
0
0
R103
0
1
1
0
0
1
1
1
0
0
0
0
0
RAMP_BUR
ST_TRIG
RAM RAM
P0_F P0_D
L
LY
RAMP0_INC[29:16]
0
0
RAM
P_LI
MIT_
HIGH
[32]
0
1
0
D0
0
0
0
0
D1
0
1
1
0
D2
0
0
1
0
D3
0
1
0
0
D4
RAM
P_LI
MIT_
LOW
[32]
0
R96
D5
0
R84
RAMP_BUR
ST_EN
0
0
D11
0
0
0
D12
R81
0
0
D13
0
RAM
P1
_DLY
RAM
P1
_RS
T
RAM
P0
_NE
XT
0
0
RAMP0
_NEXT
_TRIG
RAMP1_INC[29:16]
RAMP1_INC[15:0]
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Table 21. Full Register Map (continued)
R/W
A6
A5
A4
A3
A2
A1
A0
D15
D14
D13
D12
D11
D10
D9
R104
0
1
1
0
1
0
0
0
R105
0
1
1
0
1
0
0
1
R106
0
1
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
R107
0
1
1
0
1
0
1
1
0
0
0
0
0
0
0
0
0
R108
0
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
R109
0
1
1
0
1
1
0
1
0
0
0
0
0
0
0
0
0
D7
D6
D5
D4
D3
D2
D1
D0
RAM
RAM
P_M
P1_N
ANU
EXT
AL
0
0
0
RAM
P_T
RIG_
CAL
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RAMP1_LEN
RAMP_DLY_CNT
rb_LD_VTU
NE
R110
0
1
1
0
1
1
1
0
0
0
0
0
0
R111
0
1
1
0
1
1
1
1
0
0
0
0
0
0
0
R112
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
46
D8
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0
0
rb_VCO_SEL
RAMP1_NE
XT_TRIG
RAMP_SCALE_CO
UNT
rb_VCO_CAPCTRL
rb_VCO_DACISET
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SNAS696 – MARCH 2017
7.6.1 General Registers R0, R1, & R7
Figure 30. Registers Excluding Address
Addre
ss
R0
R1
R7
D15
D14
D13
VCO_
PHAS
RAMP
E_SY
_EN
NC_E
N
0
0
OUT_
0
FORC
E
D12
D11
D10
D9
D8
D7
OUT_ FCAL_HPFD_
MUTE
ADJ
D6
D5
D4
D3
D2
1
FCAL
_EN
MUX
OUT_
LD_S
EL
FCAL_LPFD_
ADJ
1
0
0
1
0
0
1
0
0
0
0
0
0
0
1
0
0
0
0
0
0
1
0
1
1
0
D1
D0
POW
RESE
ERDO
T
WN
CAL_CLK_DIV
0
1
0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 22. Field Descriptions
Location
Field
Type
Reset
Description
R0[15]
RAMP_EN
R/W
0
0 : Disable frequency ramping mode
1 : Enable frequency ramping mode
R0[14]
VCO_PHASE_SYNC
R/W
0
0 : Disable phase SYNC mode
1 : Enable phase SYNC mode
R0[9]
OUT_MUTE
R/W
0
Mute the outputs when the VCO is calibrating.
0 : Disabled. If disabled, also be sure to enable OUT_FORCE
1 : Enabled. If enabled, also be sure to disable OUT_FORCE
R0[8:7]
FCAL_HPFD_ADJ
R/W
R0[6:5]
FCAL_LPFD_ADJ
R/W
0
Set this field in accordance to the phase detector frequency for
optimal VCO calibration.
0: fPD ≥ 10 MHz
1: 10 MHz > fPD ≥ 5 MHz
2: 5 MHz > fPD ≥ 2.5 MHz
3: fPD < 2.5 MHz
R0[3]
FCAL_EN
R/W
0
Enablie the VCO frequency calibration. Also note that the action
of programming this bit to a 1 activates the VCO calibration
R0[2]
MUXOUT_LD_SEL
R/W
0
Selects the state of the function of the MUXout pin
0: Readback
1: Lock detect
R0[1]
RESET
R/W
0
Resets and holds all state machines and registers to default
value.
0: Normal operation
1: Reset
R0[0]
POWERDOWN
R/W
0
Powers down entire device
0: Normal operation
1: Powered down
R1[2:0]
CAL_CLK_DIV
R/W
3
Sets divider for VCO calibration state machine clock based on
input frequency.
0: fOSC ≤ 200 MHz
1: 200 MHz < fOSC ≤ 400 MHz
2: 400 MHz < fOSC ≤ 800 MHz
3: fOSC > 800 MHz
R7[14]
OUT_FORCE
R/W
0
Works with OUT_MUTE in disabling outputs when VCO
calibrating.
Set this field in accordance to the phase-detector frequency for
optimal VCO calibration.
0 : fPD ≤ 100 MHz
1: 100 MHz < fPD ≤ 150 MHz
2 : 150 MHz < fPD ≤ 200 MHz
3: fPD >200 MHz
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7.6.2 Input Path Registers
Figure 31. Registers excluding address
D15
D14
D13
R9
0
0
0
R10
R11
R12
0
0
0
0
0
1
0
0
0
D12
OSC_
2X
1
0
1
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
1
1
0
0
0
0
0
0
1
0
0
1
0
1
1
1
0
0
0
0
0
0
MULT
PLL_R
PLL_R_PRE
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 23. Field Descriptions
Location
Field
Type
Reset
Description
OSC_2X
R/W
0
Low=noise OSCin frequency doubler.
0: Disabled
1: Enabled
R10[11:7]
MULT
R/W
1
Programmable input frequency multiplier
0,2,,8-31: Reserved
1: Byapss
3: 3X
...
7: 7X
R11[11:4]
PLL_R
R/W
1
Programmable input path divider after the programmable input
frequency multiplier.
R12[11:0]
PLL_R_PRE
R/W
1
Programmable input path divider before the programmable input
frequency multiplier.
R9[12]
7.6.3 Charge Pump Registers (R13, R14)
Figure 32. Registers excluding address
R14
D15
0
D14
0
D13
0
D12
1
D11
1
D10
1
D9
1
D8
0
D7
0
D6
D5
CPG
D4
D3
0
D2
0
D1
0
D0
0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 24. Field Descriptions
Location
Field
Type
Reset
Description
R14[6:4]
CPG
R/W
7
Effective charge-pump current. This is the sum of up and down
currents.
0: 0 mA
1: 6 mA
2: Reserved
3: 12 mA
4: 3 mA
5: 9 mA
6: Reserved
7: 15 mA
48
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7.6.4 VCO Calibration Registers
Figure 33. Registers Excluding Address
D15
R8
0
R16
0
D14
VCO_
DACI
SET_
FORC
E
0
D13
D12
1
0
0
0
D11
VCO_
CAPC
TRL_
FORC
E
0
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
VCO_DACISET
R17
0
0
0
0
0
0
0
R19
0
1
1
1
1
0
VCO_
SEL_
FORC
E
0
R20
0
VCO_
SEL_
STRT
_EN
VCO_
DACI
SET_
STRT
1
0
0
0
1
VCO_SEL
0
0
VCO_CAPCTRL
0
0
1
0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 25. Field Descriptions
Location
Field
Type
Reset
Description
R8[14]
VCO_DACISET_FORCE
R/W
0
This forces the VCO_DACISET value
R8[11]
VCO_CAPCTRL_FORCE
R/W
0
This forces the VCO_CAPCTRL value
R16[8:0]
VCO_DACISET
R/W
128
This sets the final amplitude for the VCO calibration in the case
that amplitude calibration is forced.
R17[8:0]
VCO_DACISET_STRT
R/W
250
This sets the initial starting point for the VCO amplitude
calibration.
R19[7:0]
VCO_CAPCTRL
R/W
183
This sets the final VCO band when VCO_CAPCTRL is forced.
R/W
7
This sets the VCO that is used when VCO_SEL_STRT_EN=1 or
VCO_SEL_FORCE=1
0: Not Used
1: VCO1
2: VCO2
3: VCO3
4: VCO4
5: VCO5
6: VCO6
7: VCO7
R/W
0
This forces the VCO to use the core specified by VCO_SEL. It is
intended mainly for diagnostic purposes.
0: Disabled (recommended)
1: Enabled
R20[13:11] VCO_SEL
R20[10]
VCO_SEL_FORCE
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7.6.5 N Divider, MASH, and Output Registers
Figure 34. Registers Excluding Address
D15
0
D14
0
MASH
_SEE
D_EN
0
R34
R36
R37
D13
0
D12
0
D11
0
D10
0
D9
0
D8
D7
0
0
PLL_N
PFD_DLY_SEL
D6
0
D5
0
D4
0
D3
0
D2
0
0
0
0
1
MASH
_RES
ET_N
0
0
1
1
0
R38
R39
R40
R41
R42
R43
D1
D0
PLL_N[18:16]
0
0
PLL_DEN[31:16]
PLL_DEN[15:0]
MASH_SEED[31:16]
MASH_SEED[15:0]
PLL_NUM[31:16]
PLL_NUM[15:0]
R44
0
0
R45
R46
1
0
1
0
OUTB OUTA
_PD
_PD
OUTA_PWR
0
0
OUTA_MUX
0
0
OUT_ISET
1
1
0
1
1
1
1
1
MASH_ORDER
OUTB_PWR
1
1
OUTB_MUX
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 26. Field Descriptions
Location
Field
Type
Reset
Description
R34[2:0]
R36[15:0]
PLL_N
R/W
100
The PLL_N divider value is in the feedback path and divides the
VCO frequency.
0: Disabled
1: Enabled
MASH_SEED_EN
R/W
0
Enabling this bit allows the MASH_SEED to be applied to shift
the phase at the output or optimize spurs.
R37[13:8]
PFD_DLY_SEL
R/W
2
The PFD_DLY_SEL must be adjusted in accordance to the N
divider value. This is with the functional description for the N
divider.
R38[15:0]
R39[15:0]
PLL_DEN
R/W
42949672
95
The fractional denominator.
R40[15:0]
R41[15:0]
MASH_SEED
R/W
0
The initial state of the MASH engine first accumulator. Can be
used to shift phase or optimize fractional spurs. Every time the
MASH_SEED field is programmed, it ADDS this MASH seed to
the existing one. To reset it, use the MASH_RESET_N bit.
R42[15:0]
R43[15:0]
PLL_NUM
R/W
0
The fractional numerator
R44[13:8]
OUTA_PWR
R/W
31
Adjusts output power. Higher numbers give more output power
to a point, depending on the pullup component used.
R44[7]
OUTB_PD
R/W
1
Powers down output B
0: Output B active
1: Output B powered down
R44[6]
OUTA_PD
R/W
0
Powers down output A
0: Output A Active
1: Output A powered down
R44[5]
MASH_RESET_N
R/W
1
Resets MASH circuitry to an initial state
0: Disabled. Fractional mode enabled.
1: Enabled. All fractions are ignored and MASH engine is reset.
MASH_ORDER
R/W
0
Sets the MASH order
0: Integer mode
1: First order modulator
2: Second order modulator
3: Third order modulator
4: Fourth order modulator
5-7: Reserved
R37[15]
R44[2:0]
50
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Table 26. Field Descriptions (continued)
Type
Reset
Description
R45[12:11] OUTA_MUX
Location
Field
R/W
1
Selects what signal goes to RFoutA
0: Channel divider
1: VCO
2: Reserved
3: High impedance
R45[10:9]
OUT_ISEL
R/W
0
Setting to a lower value allows slightly higher output power at
higher frequencies at the expense of higher current
consumption.
0: Maximum output power boost
...
3: No output power boost
R45[5:0]
OUTB_PWR
R/W
31
Output power setting for RFoutB.
R46[1:0]
OUTB_MUX
R/W
1
Selects what signal goes to RFoutB
0: Channel divider
1: VCO
2: Sysref
3: High impedance
7.6.6 Lock Detect Registers
Figure 35. Registers Excluding Address
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R59
R60
D0
LD_T
YPE
LD_DLY
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 27. Field Descriptions
Location
R59[0]
R60[15:0]
Field
Type
Reset
Description
LD_TYPE
R/W
1
Lock detect type
0: VCO calibration status
1: VCO calibration status and Vtune
LD_DLY
R/W
1000
This is the delay added to the lock detect after the VCO
calibration is successful. It is in phase-detector cycles.
7.6.7 MASH_RESET
Figure 36. Registers Excluding Address
D15
D14
D13
D12
D11
D10
R69
R70
D9
D8
D7
D6
MASH_RST_COUNT[31:16]
MASH_RST_COUNT[15:0]
D5
D4
D3
D2
D1
D0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 28. Field Descriptions
Location
Field
Type
Reset
Description
R69[15:0]
R70[15:0]
MASH_RST_COUNT
R/W
50000
If not using this device in fractional mode with
VCO_PHASE_SYNC=1, then this field can be set to 0. In phasesync mode with fractions, this bit is used so that there is a delay
for the VCO divider after the MASH is reset. This delay must be
set to greater than the lock time of the PLL. It does impact the
latency time of the SYNC feature.
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7.6.8 SysREF Registers
Figure 37. Registers Excluding Address
D15
D14
D13
D12
D11
R71
0
0
0
0
0
R72
R73
R74
0
0
0
0
0
0
0
0
SYSREF_PULSE_CNT
0
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
SYSR
SYSR SYSR
EF_R
0
0
0
SYSREF_DIV_PRE
EF_P EF_E
0
EPEA
ULSE
N
T
SYSREF_DIV
JESD_DAC2_CTRL
JESD_DAC1_CTRL
JESD_DAC4_CTRL
JESD_DAC3_CTRL
D0
1
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 29. Field Descriptions
Location
Field
Type
Reset
Description
R71[7:5]
STSREF_DIV_PRE
R/W
4
Pre divider for SYSREF
2: Divide by 2
4: Divide by 4
All other states: invalid
R71[4]
SYSREF_PULSE
R/W
0
Enable pulser mode in master mode
0: Disabled
1: Enabled
R71[3]
SYSREF_EN
R/W
0
Enable SYSREF
R71[2]
SYSREF_REPEAT
R/W
0
Enable repeater mode
0: Master mode
1: Repeater mode
R72[10:0]
SYSREF_DIV
R/W
0
Divider for the SYSREF
Fout = Fin / (2 × SYSREF_DIV + 4)
These are the adjustments for the delay for the SYSREF. Two of
these must be zero and the other two values must sum to 63.
R73[5:0]
JESD_DAC1_CTRL
R/W
63
R73[11:6]
JESD_DAC2_CTRL
R/W
0
R74[5:0]
JESD_DAC3_CTRL
R/W
0
R74[11:6]
JESD_DAC4_CTRL
R/W
0
R/W
0
R74[15:12] SYSREF_PULSE_CNT
52
Number of pulses in pulse mode in master mode
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7.6.9 CHANNEL Divider Registers
Figure 38. Registers Excluding Address
Reg
15
0
R75
14
0
13
0
12
0
11
1
10
9
8
CHDIV
7
6
5
0
4
0
3
0
2
0
1
0
0
0
D9
D8
D7
D6
D5
D4
D3
QUIC
K_RE
VCO_CAPCTRL_STRT
CAL_
EN
RAMP_THRESH[31:16]
RAMP_THRESH[15:0]
D2
D1
D0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 30. Field Descriptions
Location
Field
Type
Reset
Description
R75[10:6]
CHDIV
R/W
0
VCO divider value
0: 2
1: 4
2: 6
3: 8
4: 12
5: 16
6: 24
7: 32
8: 48
9: 64
10: 72
11: 96
12: 128
13: 192
14: 256
15: 384
16: 512
17: 768
18-31: Reserved
7.6.10 Ramping and Calibration Fields
Figure 39. Registers Excluding Address
D15
D14
D13
D12
0
0
0
0
R78
D11
RAMP
_THR
ESH[3
2]
D10
0
R79
R80
1
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 31. Field Descriptions
Location
Field
Type
Reset
Description
R78[11]
R79[15:0]
R80[15:0]
RAMP_THRESH
R/W
0
This sets how much the ramp can change the VCO frequency
before calibrating. If this frequency is chosen to be Δf, then it is
calculated as follows:
RAMP_THRESH = (Δf / fPD) × 16777216
QUICK_RECAL_EN
R/W
0
Causes the initial VCO_CORE, VCO_CAPCTRL, and
VCO_DACISET to be based on the last value. Useful if the
frequency change is small, as is often the case for ramping.
0: Disabled
1: Enabled
VCO_CAPCTRL_STRT
R/W
0
This is the capcode that is used for the calibration when
VCO_CAPCTRL_STRT_EN = 1. Smaller values yield a higher
frequency band within a VCO core. Valid number range is 0 to
183.
R78[9]
R78[8:1]
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7.6.11 Ramping Registers
These registers are only relevant for ramping functions and are enabled if and only if RAMP_EN (R0[15]) = 1.
7.6.11.1 Ramp Limits
Figure 40. Registers Excluding Address
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R81
R82
R83
D0
RAMP
_LIMI
T_HIG
H[32]
RAMP_LIMIT_HIGH[31:16]
RAMP_LIMIT_HIGH[15:0]
R84
0
0
0
0
0
0
0
R85
R86
0
0
0
RAMP
_LIMI
T_LO
W[32]
RAMP_LIMIT_LOW[31:16]
RAMP_LIMIT_LOW[15:0]
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 32. Field Descriptions
Location
Field
Type
Reset
Description
R81[0]
R82[15:0]
R83[15:0]
RAMP_LIMIT_HIGH
R/W
0
This sets a maximum frequency that the ramp can not exceed
so that the VCO does not get set beyond a valid frequency
range. Suppose fHIGH is this frequency and fVCO is the starting
VCO frequency then:
For fMAX ≥ fVCO:
RAMP_LIMIT_HIGH = (fHIGH - fVCO)/fPD × 16777216
For fMAX < fVCO this is not a valid condition to choose.
R84[0]
R85[15:0]
R86[15:0]
RAMP_LIMIT_LOW
R/W
0
This sets a minimum frequency that the ramp can not exceed so
that the VCO does not get set beyond a valid frequency range.
Suppose fLOW is this frequency and fVCO is the starting VCO
frequency then:
For fLOW ≤ fVCO:
RAMP_LIMIT_LOW =232 - (fLOW - fVCO) / fPD × 16777216
For fLOW > fVCO this is not a valid condition to choose.
7.6.11.2
54
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7.6.11.3 Ramping Triggers, Burst Mode, and RAMP0_RST
Figure 41. Registers Excluding Address
R96
R97
D15
RAMP
_BUR
ST_E
N
RAMP
0_RS
T
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
RAMP_BURST_COUNT
0
0
0
1
RAMP_TRIGB
RAMP_TRIGA
0
D1
D0
0
0
RAMP_BURS
T_TRIG
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 33. Field Descriptions
Location
R96[15]
Field
Type
Reset
Description
RAMP_BURST_EN
R/W
0
Enables burst ramping mode. In this mode, a
RAMP_BURST_COUNT ramps are sent out when RAMP_EN is
set from 0 to 1.
0: Disabled
1: Enabled
R/W
0
Sets how many ramps are run in burst ramping mode.
RAMP96[1 RAMP_BURST_COUNT
4:2]
R97[15]
RAMP0_RST
R/W
0
Resets RAMP0 at start of ramp to eliminate round-off errors.
Must only be used in automatic ramping mode.
0: Disabled
1: Enabled
R97[6:3]
RAMP_TRIGA
R/W
0
Multipurpose Trigger A definition:
0: Disabled
1: RampCLK pin rising edge
2: RampDIR pin rising edge
4: Always triggered
9: RampCLK pin falling edge
10: RampDIR pin falling edge
All other states: reserved
R97[10:7]
RAMP_TRIGB
R/W
0
Multipurpose trigger B definition:
0: Disabled
1: RampCLK pin Rising Edge
2: RampDIR pin Rising Edge
4: Always Triggered
9: RampCLK pin Falling Edge
10: RampDIR pin Falling Edge
All other states: Reserved
R97[1:0]
RAMP_BURST_TRIG
R/W
0
Ramp burst trigger definition that triggers the next ramp in the
count. Note that RAMP_EN starts the count, not this word.
0: Disabled
1: RampCLK pin rising edge
5: CMP0 detected
8: Always triggered
All other states: reserved
7.6.11.4 Ramping Configuration
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Figure 42. Registers Excluding Address
D15
D14
D13
D12
D11
D10
R98
D9
D8
D7
D6
D5
D4
D3
D2
RAMP0_INC[29:16]
R99
R100
D1
0
D0
RAMP
0_DL
Y
RAMP0_INC[15:0]
RAMP0_LEN
R101
0
0
R102
R103
R104
0
0
0
0
R105
0
0
RAMP
RAMP RAMP
0
0
0
1
1
_NEX
_DLY _RST
T
RAMP1_INC[29:16]
RAMP1_INC[15:0]
RAMP1_LEN
RAMP
RAMP
1
_MAN
_NEX
UAL
T
RAMP
0
0
0
0
_TRIG
_CAL
0
RAMP_DLY_CNT
R106
0
0
0
0
0
0
0
0
RAMP
0_
NEXT
_TRIG
RAMP0_
NEXT_TRIG
0
0
RAMP1_
NEXT_TRIG
0
RAMP_SCALE_COUN
T
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 34. Field Descriptions
Location
Field
Type
Reset
Description
R98[15:2]
R99[15:0]
RAMP0_INC
R/W
0
2's complement of the amount the RAMP0 is incremented in
phase detector cycles.
R98[0]
RAMP0_DLY
R/W
0
Enabling this bit uses two clocks instead of one to clock the
ramp. Effectively doubling the length.
0: Normal ramp length
1: Double ramp length
R100[15:0] RAMP0_LEN
R/W
0
Length of RAMP0 in phase detector cycles
R101[6]
RAMP1_DLY
R/W
0
Enabling this bit uses two clocks instead of one to clock the
ramp. Effectively doubling the length.
0: Normal ramp length
1: Double ramp length
R101[5]
RAMP1_RST
R/W
0
Resets RAMP1 to eliminate rounding errors. Must be used in
automatic ramping mode.
0: Disabled
1: Enabled
R101[4]
RAMP0_NEXT
R/W
0
Defines what ramp comes after RAMP0
0: RAMP0
1: RAMP1
RAMP0_NEXT_TRIG
R/W
0
Defines what triggers the next ramp
0: RAMP0_LEN timeout counter
1: Trigger A
2: Trigger B
3: Reserved
R102[13:0] RAMP1_INC
R103[15:0]
R/W
0
2's complement of the amount the RAMP0 is incremented in
phase detector cycles.
R104[15:0] RAMP1_LEN
R/W
0
Length of RAMP1 in phase detector cycles
R105[15:6] RAMP_DLY_CNT
R/W
0
This is the amount of time for the VCO calibration in automatic
mode. If the VCO calibration is less, then it is this time. if it is
more then the time is the VCO caliabration time.
R101[1:0]
R105[5]
RAMP_MANUAL
R/W
0
Enables manual ramping mode, otherwise automatic mode
0: Automatic ramping mode
1: Manual ramping mode
R105[4]
RAMP1_NEXT
R/W
0
Determines what ramp comes after RAMP1:
0: RAMP0
1: RAMP1
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Table 34. Field Descriptions (continued)
Location
Field
Type
Reset
Description
R105[1:0]
RAMP_NEXT_TRIG
R/W
0
Defines what triggers the next ramp
0: RAMP1_LEN timeout counter
1: Trigger A
2: Trigger B
3: Reserved
RAMP_TRIG_CAL
R/W
0
Enabling this bit forces the VCO to calibrate after the ramp.
RAMP_SCALE_COUNT
R/W
7
Multiplies RAMP_DLY count by 2RAMP_SCALE_COUNT
R106[4]
R106[2:0]
7.6.12 Readback Registers
Figure 43. Registers Excluding Address
D15
D14
D13
D12
D11
R110
0
0
0
0
0
R111
R112
0
0
0
0
0
0
0
0
0
0
D10
D9
rb_LD_
VTUNE
0
0
0
0
D8
0
D7
D6
rb_VCO_SEL
0
D5
D4
D3
D2
D1
D0
0
0
0
0
0
rb_VCO_CAPCTRL
rb_VCO_DACISET
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 35. Field Descriptions
Type
Reset
Description
R110[10:9] rb_LD_VTUNE
Location
Field
R
0
Readback of Vtune lock detect
0: Unlocked (Vtune low)
1: Unlocked (Vtune high)
2: Locked
3: Invalid State
R110[7:5]
rb_VCO_SEL
R
0
Reads back the actual VCO that the calibration has selected.
0: Invalid
1: VCO1
...
7: VCO7
R111[7:0]
rb_VCO_CAPCTRL
R
183
Reads back the actual CAPCTRL capcode value the VCO
calibration has chosen.
R112[8:0]
rb_VCO_DACISET
R
170
Reads back the actual amplitude (DACISET) value that the VCO
calibration has chosen.
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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
8.1.1 OSCin Configuration
OSCin supports single or differential-ended clock.
Table 36. OSCin Configuration
OSCin TYPE
SINGLE-ENDED CLOCK
DIFFERENTIAL CLOCK
VT
0.1 µF
OSCin
OSCin
Connection diagram
VT
50 Ÿ
OSCin*
OSCin*
50 Ÿ
Input clock definitions are shown in Figure 44:
VOSCin
VOSCin
VOSCin
CMOS
Sine wave
Differential
Figure 44. Input Clock Definitions
8.1.2 OSCin Slew Rate
The slew rate of the OSCin signal can have an impact on the spurs and phase noise of the LMX2594 if it is too
low. In general, the best performance is for a high slew rate, but lower amplitude signal, such as LVDS.
8.1.3 RF Output Buffer Power Control
The OUTA_PWR and OUTB_PWR registers can be used to control the output power of the output buffers. The
setting for optimal power may depend on the pullup component, but typically is around 50. The higher the setting,
the higher the current consumption of the output buffer.
8.1.4 RF Output Buffer Pullup
The choice of output buffer components is very important and can have a profound impact on the output power.
Table 37 shows how to treat each pin. If using single-ended, the pullup is still needed, and user puts a 50-Ω
resistor after the capacitor.
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Table 37. Different Methods for Pullup on Outputs
PULLUP STYLE
DIAGRAM
COMMENTS
+vcc
Potentially higher output power,
but output impedance is far from
50 Ω. Consider also using with a
resistive pad.
L
Inductor
C
RFoutAP
+vcc
Resistor
More consistent matching
R
C
RFoutAP
Table 38. Output Pullup Configuration
COMPONENT
VALUE
Inductor
Varies with frequency
PART NUMBER
Resistor
50 Ω
Vishay FC0402E50R0BST1
Capacitor
Varies with frequency
ATC 520L103KT16T
ATC 504L50R0FTNCFT
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8.2 Typical Application
Figure 45. Typical Application Schematic
8.2.1 Design Requirements
The design of the loop filter is complex and is typically done with software. The PLLatinum Sim software is an
excellent resource for doing this and the design is shown in the Figure 46. For those interested in the equations
involved, the PLL Performance, Simulation, and Design Handbook listed in the end of this document goes into
great detail as to theory and design of PLL loop filters.
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Typical Application (continued)
Figure 46. PLLatinum Sim Design Screen
8.2.2 Detailed Design Procedure
The integration of phase noise over a certain bandwidth (jitter) is an performance specification that translates to
signal-to-noise ratio. Phase noise inside the loop bandwidth is dominated by the PLL, while the phase noise
outside the loop bandwidth is dominated by the VCO. Generally, jitter is lowest if loop bandwidth is designed to
the point where the two intersect. A higher phase margin loop filter design has less peaking at the loop
bandwidth and thus lower jitter. The tradeoff with this is longer lock times and spurs must be considered in
design as well.
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Typical Application (continued)
8.2.3 Application Curves
Figure 47. Typical Jitter
62
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9 Power Supply Recommendations
TI recommends placement of 100 nF close to each of the power supply pins. If fractional spurs are a large
concern, using a ferrite bead to each of these power supply pins can reduce spurs to a small degree. This device
has integrated LDOs, which improves the resistance to power supply noise. However, the pullup components on
the RFoutA and RFoutB pins on the outputs have a direct connection to the power supply, so extra care must be
made to ensure that the voltage is clean for these pins. Figure 48 is a typical application example.
This device can be powered by an external DC-DC buck converter, such as the TPS62150. Note that although
Rtps, Rtps1, and Rtps2 are 0 Ω in the schematic, they could be potentially replaced with a larger resistor value or
inductor value for better power supply filtering.
Figure 48. Using the TPS62150 as a Power Supply
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10 Layout
10.1 Layout Guidelines
In general, the layout guidelines are similar to most other PLL devices. Here are some specific guidelines.
• GND pins may be routed on the package back to the DAP.
• The OSCin pins, these are internally biased and must be AC coupled.
• If not used, RampCLK, RampDIR, and SysRefReq can be grounded to the DAP.
• For the Vtune pin, try to get a loop filter capacitor as close to this as possible. This may mean separating it
from the rest of the loop filter.
• For the outputs, keep the pullup component as close as possible to the pin and use the same component on
each side of the differential pair.
• If a single-ended output is needed, the other side must have the same loading and pullup. However, the
routing for the used side can be optimized by routing the complementary side through a via to the other side
of the board. On this side, use the same pullup and make the load look equivalent to the side that is used.
• Ensure DAP on device is well-grounded with many vias, preferably copper filled.
• Have a thermal pad that is as large as the LMX2594 exposed pad. Add vias to the thermal pad to maximize
thermal performance.
• Use a low loss dielectric material, such as Rogers 4003, for optimal output power.
• See instructions for the LMX2594EVM (LMX2594 EVM Instructions, 15 GHz Wideband Low Noise PLL with
Integrated VCO) for more details on layout.
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10.2 Layout Example
Figure 49. LMX2594 PCB Layout
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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
Texas Instruments has several software tools to aid in the development at www.ti.com. Among these tools are:
• EVM software to understand how to program the LMX2594 and for programming the EVM board.
• EVM board instructions for seeing typical measured data with detailed measurement conditions and a
complete design.
• PLLatinum Sim program for designing loop filters, simulating phase noise, and simulating spurs on the
LMX2594.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
• AN-1879 Fractional N Frequency Synthesis
• PLL Performance, Simulation, and Design Handbook
• LMX2594 EVM Instructions, 15 GHz Wideband Low Noise PLL with Integrated VCO
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.4 Community Resources
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.
11.5 Trademarks
E2E is a trademark of Texas Instruments.
11.6 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.
11.7 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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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.
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PACKAGE OPTION ADDENDUM
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30-Mar-2017
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)
LMX2594RHAR
ACTIVE
VQFN
RHA
40
2500
Green (RoHS
& no Sb/Br)
CU NIPDAUAG
Level-3-260C-168 HR
-40 to 85
LMX2594
LMX2594RHAT
ACTIVE
VQFN
RHA
40
250
Green (RoHS
& no Sb/Br)
CU NIPDAUAG
Level-3-260C-168 HR
-40 to 85
LMX2594
(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.
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.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
30-Mar-2017
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 MATERIALS INFORMATION
www.ti.com
31-Mar-2017
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
LMX2594RHAR
VQFN
RHA
40
2500
330.0
16.4
6.3
6.3
1.5
12.0
16.0
Q1
LMX2594RHAT
VQFN
RHA
40
250
178.0
16.4
6.3
6.3
1.5
12.0
16.0
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
31-Mar-2017
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
LMX2594RHAR
VQFN
RHA
40
2500
367.0
367.0
38.0
LMX2594RHAT
VQFN
RHA
40
250
210.0
185.0
35.0
Pack Materials-Page 2
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