TI ADS61B49IRGZR

ADS61B29
ADS61B49
www.ti.com ......................................................................................................................................... SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008
14-/12-Bit, 250-MSPS ADCs With Integrated Analog Buffer
FEATURES
1
•
•
•
•
•
•
•
•
•
•
•
Integrated High Impedance Analog Input
Buffer
Maximum Sample Rate: 250 MSPS
14-Bit Resolution – ADS61B49
12-Bit Resolution – ADS61B29
790 mW Total Power Dissipation at 250 MSPS
Double Data Rate (DDR) LVDS and Parallel
CMOS Output Options
Programmable Fine Gain up to 6 dB for
SNR/SFDR Trade-Off and 1-Vpp Full-Scale
Operation
DC Offset Correction
Supports Input Clock Amplitude Down to 400
mVPP Differential
48-QFN Package (7mm × 7mm)
Pin Compatible with ADS6149 Family
APPLICATIONS
•
•
•
•
•
•
•
•
•
Multicarrier, Wide Bandwidth Communications
Wireless Multi-Carrier Communications
Infrastructure
Software Defined Radio
Power Amplifier Linearization Feedback ADC
802.16d/e
Test and Measurement Instrumentation
High Definition Video
Medical Imaging
Radar Systems
DESCRIPTION
The ADS61B49 (ADS61B29) is a 14-bit (12-bit) A/D
converter with a sampling rate up to 250 MSPS. It
combines high dynamic performance and low power
consumption in a compact 48-QFN package. An
integrated analog buffer makes it well-suited for
multi-carrier,
wide
bandwidth
communications
applications.
The
buffer
maintains
constant
performance and input impedance across a wide
frequency range.
The ADS61B49 (ADS61B29) has fine gain options
that can be used to improve SFDR performance at
lower full-scale input ranges. It includes a dc offset
correction loop that can be used to cancel the ADC
offset. Both Double Data Rate (DDR) LVDS and
parallel CMOS digital output interfaces are available.
At lower sampling rates, the ADC automatically
operates at scaled down power with no loss in
performance.
It includes internal references while the traditional
reference pins and associated decoupling capacitors
have been eliminated. The device is specified over
the industrial temperature range (–40°C to 85°C).
ADS614X
14-Bit Family
ADS612X
12-Bit Family
ANALOG
BUFFER
250 MSPS
210 MSPS
NO
ADS6149
ADS6148
YES
ADS61B49
NO
ADS6129
YES
ADS61B29
ADS6128
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008, Texas Instruments Incorporated
ADS61B29
ADS61B49
SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008 ......................................................................................................................................... www.ti.com
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.
DRGND
DRVDD
AGND
AVDD
ADS61B49 BLOCK DIAGRAM
LVDS
Interface
CLKP
CLKOUTP
CLOCKGEN
CLKM
CLKOUTM
D0_D1_P
D0_D1_M
D2_D3_P
Analog
Buffer
D2_D3_M
D4_D5_P
D4_D5_M
INP
Sample
and
Hold
14-Bit ADC
Digital
Encoder
Serializer
D6_D7_P
D6_D7_M
INM
D8_D9_P
D8_D9_M
D10_D11_P
D10_D11_M
VCM
Control
Interface
Reference
D12_D13_P
D12_D13_M
OVR_SDOUT
DFS
MODE
SEN
SDATA
SCLK
RESET
ADS61B49
B0095-08
2
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ADS61B29
ADS61B49
www.ti.com ......................................................................................................................................... SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008
DRGND
DRVDD
AGND
AVDD
ADS61B29 BLOCK DIAGRAM
LVDS
Interface
CLKP
CLKOUTP
CLOCKGEN
CLKM
CLKOUTM
D0_D1_P
D0_D1_M
D2_D3_P
Analog
Buffer
D2_D3_M
D4_D5_P
D4_D5_M
INP
Sample
and
Hold
14-Bit ADC
Digital
Encoder
Serializer
D6_D7_P
D6_D7_M
INM
D8_D9_P
D8_D9_M
D10_D11_P
D10_D11_M
VCM
Control
Interface
Reference
OVR_SDOUT
DFS
MODE
SEN
SDATA
SCLK
RESET
ADS61B29
B0095-09
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ADS61B29
ADS61B49
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PACKAGE/ORDERING INFORMATION (1) (2)
PRODUCT
PACKAGELEAD
PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
LEAD/BALL
FINISH
PACKAGE
MARKING
ADS61B49
QFN-48
RGZ
–40°C to 85°C
Cu NiPdAu
AZ61B49
ADS61B29
QFN-48
RGZ
–40°C to 85°C
Cu NiPdAu
AZ61B29
(1)
(2)
ORDERING
NUMBER
TRANSPORT MEDIA,
QUANTITY
ADS61B49IRGZR
Tape and reel
ADS61B49IRGZT
ADS61B29IRGZR
Tape and reel
ADS61B29IRGZT
For thermal pad size on the package, see the mechanical drawings at the end of this data sheet. θJA = 25.41° C/W (0LFM air flow), θJC
= 16.5° C/W when used with 2oz. copper trace and pad soldered directly to a JEDEC standard four layer 3 in x 3 in (7.62 cm x 7.62 cm)
PCB.
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
website at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
VALUE
UNIT
Supply Voltage, AVDD
-0.3 to 3.9
V
Supply Voltage, DRVDD
-0.3 to 2.2
V
Voltage between AGND and DRGND
-0.3 to 0.3
V
Voltage between AVDD to DRVDD (when AVDD leads DRVDD)
0 to 3.3
V
Voltage between DRVDD to AVDD (when DRVDD leads AVDD)
-1.5 to 1.8
V
-0.3 to minimum (3.6, AVDD + 0.3)
V
-0.3 to (AVDD + 0.3)
V
Voltage applied to analog input pins - INP, INM
Voltage applied to input pins - CLKP, CLKM (2), RESET, SCLK,
SDATA, SEN, DFS and MODE
TA
Operating free-air temperature range
-40 to 85
°C
TJ
Max Operating junction temperature
125
°C
Tstg
Storage temperature range
-65 to 150
°C
(1)
(2)
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability.
When AVDD is turned off, it is recommended to switch off the input clock (or ensure the voltage on CLKP, CLKM is < 0.3V.) This
prevents the ESD protection diodes at the clock input pins from turning on.
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
UNIT
3
3.3
3.6
V
1.7
1.8
1.9
V
SUPPLIES
AVDD
Analog supply voltage
DRVDD
Digital supply voltage
ANALOG INPUTS
Differential input voltage range
2
Vpp
Input common-mode voltage (different than ADS6149 family)
2.3 ±0.1
Maximum analog input frequency with 2Vpp input amplitude (1)
500
MHz
V
Maximum analog input frequency with 1Vpp input amplitude (1)
800
MHz
CLOCK INPUT
Input clock sample rate
1
Sine wave, ac-coupled
Input clock amplitude differential
(VCLKP–VCLKM)
(1)
4
0.3
250
MSPS
1.5
LVPECL, ac-coupled
1.6
LVDS, ac-coupled
0.7
LVCMOS, single-ended, ac-coupled
3.3
Vpp
V
See the Theory of Operations in the applications section.
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ADS61B29
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RECOMMENDED OPERATING CONDITIONS (continued)
over operating free-air temperature range (unless otherwise noted)
Input clock duty cycle
MIN
NOM
MAX
40%
50%
60%
UNIT
DIGITAL OUTPUTS
CL
Maximum external load capacitance from each output pin to DRGND
RL
Differential load resistance between the LVDS output pairs (LVDS mode)
TA
Operating free-air temperature
5
pF
Ω
100
–40
85
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°C
5
ADS61B29
ADS61B49
SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008 ......................................................................................................................................... www.ti.com
ELECTRICAL CHARACTERISTICS – ADS61B49 and ADS61B29
Typical values are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1 dBFS differential analog input, internal
reference mode unless otherwise noted.
Min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C, AVDD = 3.3 V, DRVDD = 1.8 V
PARAMETER
ADS61B49/ADS61B29
250 MSPS
MIN
TYP
UNIT
MAX
ANALOG INPUT
Differential input voltage range
Differential input resistance (at dc), See Figure 62
Differential input capacitance, See Figure 63
2
VPP
10
kΩ
2
Analog input bandwidth
pF
750
Analog Input common-mode current (per input pin)
MHz
µA
2
VCM common-mode output voltage (different than ADS6149 family)
2.3
V
VCM output current capability
±4
mA
DC ACCURACY
Offset error
-15
Temperature coefficient of offset error
Gain error due to internal reference inaccuracy alone
EGCHAN
Gain error of channel alone
Temperature coefficient of EGCHAN
+15
0.005
Variation of offset error with supply
EGREF
±2
mV/°C
0.3
-2.5
±0.2
mV
mV/V
+2.5
%FS
0.2
%FS
.001
Δ%/°C
POWER SUPPLY
IAVDD
IDRVDD
Analog supply current
200
mA
Output buffer supply current, LVDS interface with 100-Ω external termination
70
mA
Output buffer supply current, CMOS interface Fin = 3 MHz,
10-pF external load capacitance
56
mA
Analog power
660
730
mW
Digital power LVDS interface
130
160
mW
Digital power CMOS interface, Fin = 3 MHz, 10-pF external load capacitance
101
Global power down
20
Standby
6
120
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mW
75
mW
mW
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ADS61B29
ADS61B49
www.ti.com ......................................................................................................................................... SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008
ELECTRICAL CHARACTERISTICS – ADS61B49 and ADS61B29
Typical values are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1 dBFS differential analog input, internal
reference mode unless otherwise noted.
Min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C, AVDD = 3.3 V, DRVDD = 1.8 V
PARAMETER
ADS61B49
250 MSPS
MIN
SNR
Signal-to-noise ratio, LVDS
MIN
72.3
70.1
72
69.8
71.6
69.6
Fin = 100 MHz
68.5
70.7
66.5
67.8
Fin = 20 MHz
72.5
70.3
Fin = 80 MHz
71.8
69.7
Fin = 100 MHz
71.6
67.5
dBFS
69
69
Fin = 170 MHz
UNIT
TYP MAX
Fin = 80 MHz
Fin = 300 MHz
ENOB
Effective number of bits
TYP MAX
Fin = 20 MHz
Fin = 170 MHz
SINAD
Signal-to-noise and distortion ratio, LVDS
ADS61B29
250 MSPS
69.5
70
65.7
dBFS
68.4
Fin = 300 MHz
67.1
66.3
Fin = 170 MHz (using SINAD in dBFS)
11.3
11.1
LSB
DNL
Differential non-linearity
-0.95
±0.4
1
-0.5
±0.2
1
LSB
INL
Integrated non-linearity
-5
±2
5
-2.5
±1
2.5
LSB
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ADS61B29
ADS61B49
SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008 ......................................................................................................................................... www.ti.com
ELECTRICAL CHARACTERISTICS – ADS61B49 and ADS61B29
Typical values are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1 dBFS differential analog input, internal
reference mode unless otherwise noted.
Min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C, AVDD = 3.3 V, DRVDD = 1.8 V
PARAMETER
ADS61B49/ADS61B29
250 MSPS
MIN
SFDR
Spurious free dynamic range
THD
Total harmonic distortion
Fin = 20 MHz
92
Fin = 80 MHz
86
Fin = 100 MHz
86
Fin = 170 MHz (all spurs/harmonics)
74
84
Fin = 170 MHz (excluding 2nd harmonic)
77
87
Fin = 300 MHz
76
Fin = 20 MHz
89
Fin = 80 MHz
83
Fin = 100 MHz
Fin = 170 MHz
HD2,
Second harmonic distortion
73
94
Fin = 80 MHz
90
Fin = 100 MHz
76
Fin = 20 MHz
93
Fin = 80 MHz
86
Fin = 100 MHz
76
Fin = 20 MHz
96
Fin = 80 MHz
94
Fin = 100 MHz
94
80
90
F1 = 46 MHz, F2 = 50 MHz,
Each tone at –7 dBFS
94
F1 = 185 MHz, F2 = 190 MHz,
Each tone at –7 dBFS
90
PSRR
AC power supply rejection ratio
For 100-mVpp signal on AVDD supply
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dBc
dBc
dBc
92
Fin = 300 MHz
Recovery to within 1% (of final value) for 6-dB
overload with sine wave input
dBc
87
Fin = 300 MHz
Input overload recovery
8
85
77
dBc
84
Fin = 300 MHz
Fin = 170 MHz
IMD
2-tone inter-modulation distortion
88
74
UNIT
MAX
79
Fin = 20 MHz
Fin = 170 MHz
Worst Spur
Other than second, third harmonics
82
72
Fin = 300 MHz
Fin = 170 MHz
HD3
Third harmonic distortion
TYP
dBFS
1
Clock
Cycles
25
dB
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DIGITAL CHARACTERISTICS – ADS61B49 and ADS61B29
The DC specifications refer to the condition where the digital outputs are not switching, but are permanently at a valid logic
level 0 or 1. AVDD = 3.3 V, DRVDD = 1.8 V
PARAMETER
ADS61B49/ADS61B29
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DIGITAL INPUTS – RESET, SCLK, SDATA, SEN (1)
High-level input voltage
All digital inputs support 1.8-V and 3.3-V CMOS
logic levels
Low-level input voltage
High-level input current
Low-level input current
1.3
V
0.4
SDATA, SCLK (2)
VHigh = 3.3 V
16
SEN (3)
VHigh = 3.3 V
10
SDATA, SCLK
VLow = 0 V
0
SEN
VLow = 0 V
–20
Input capacitance
V
µA
µA
4
pF
V
DIGITAL OUTPUTS – CMOS INTERFACE (Pins D0 to D13 and OVR_SDOUT)
High-level output voltage
with IOH = 1mA
DRVDD
DRVDD
-0.1
Low-level output voltage
with IOL = 1mA
0
Output capacitance (internal to device)
0.1
2
V
pF
DIGITAL OUTPUTS – LVDS INTERFACE (Pins D0_D1_P/M to D12_D13_P/M) (4)
VODH, High-level output voltage (5)
VODL, Low-level output voltage
(5)
VOCM, Common-mode output voltage
275
350
425
mV
–425
–350
–275
mV
1
1.2
1.3
Capacitance inside the device, from either output
to ground
Output capacitance
(1)
(2)
(3)
(4)
(5)
2
V
pF
SCLK, SDATA, SEN function as digital input pins in serial configuration mode.
SDATA, SCLK have internal 200-kΩ pull-down resistor.
SEN has internal 100-kΩ pull-up resistor to AVDD.
OVR_SDOUT has CMOS output logic levels, determined by DRVDD voltage.
With external 100-Ω termination
Dn_Dn+1_P
Dn_Dn+1_P
Logic 1
Logic 0
VODL = –350 mV
(1)
VODH = 350 mV
(1)
Dn_Dn+1_M
Dn_Dn+1_M
V
V
OCM
OCM
GND
GND
T0399-01
Figure 1. LVDS Voltage Levels
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TIMING REQUIREMENTS – LVDS AND CMOS MODES (1)
Typical values are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, sampling frequency = 250 MSPS, sine wave input clock,
CLOAD = 5 pF (2), RLOAD = 100 Ω (3), Low Speed mode disabled, unless otherwise noted.
Min and max values are across the full temperature range TMIN = –40°C to TMAX = 85°C, AVDD = 3.3 V, DRVDD = 1.7 V to
1.9 V.
PARAMETER
ta
Aperture delay
tj
Aperture jitter
Wake-up time
ADC Latency (4)
DDR LVDS MODE
TEST CONDITIONS
MIN
TYP
MAX
0.7
1.2
1.7
170
UNIT
ns
fs rms
Time to valid data after coming out of STANDBY mode
0.3
1
Time to valid data after coming out of PDN GLOBAL mode
25
100
Time to valid data after stopping and restarting the input clock
10
Clock
Cycles
Default, after reset
18
Clock
Cycles
0.8
1.2
ns
0.25
0.6
ns
µs
(5)
(6)
tsu
Data setup time
Data valid
th
Data hold time
Zero-crossing of CLKOUT to data becoming invalid (6)
tPDI
Clock propagation delay
Input clock rising edge cross-over to output clock rising edge cross-over
100 MSPS ≤ Sampling frequency ≤ 250 MSPS
tdelay
to zero-crossing of CLKOUTP
0.2 × ts + tdelay
5
6.2
ns
7.5
ns
LVDS bit clock duty cycle
Duty cycle of differential clock, (CLKOUTP–CLKOUTM)
100 MSPS ≤ Sampling frequency ≤ 250 MSPS
tRISE,
tFALL
Data rise time,
Data fall time
Rise time measured from –100 mV to 100 mV
Fall time measured from 100 mV to –100 mV
1 MSPS ≤ Sampling frequency ≤ 250 MSPS
0.08
0.14
0.2
ns
tCLKRISE,
tCLKFALL
Output clock rise time,
Output clock fall time
Rise time measured from –100 mV to 100 mV
Fall time measured from 100 mV to –100 mV
1 MSPS ≤ Sampling frequency ≤ 250 MSPS
0.08
0.14
0.2
ns
tOE
Output enable (OE) to data delay
Time to valid data after OE becomes active
52%
40
ns
PARALLEL CMOS MODE (7)
tSTART
Input clock to data delay
Input clock rising edge cross-over to start of data valid (8)
tDV
Data valid time
Time interval of valid data (8)
0.7
tPDI
Clock propagation delay
Input clock rising edge cross-over to output clock rising edge cross-over
100 MSPS ≤ Sampling frequency ≤ 150 MSPS
0.78 × ts + tdelay
tdelay
3.2
5
1.5
6.5
ns
ns
ns
8
ns
Output clock duty cycle
Duty cycle of differential clock, (CLKOUT)
100 MSPS ≤ Sampling frequency ≤ 150 MSPS
tRISE,
tFALL
Data rise time,
Data fall time
Rise time measured from 20% to 80% of DRVDD,
Fall time measured from 80% to 20% of DRVDD,
1 MSPS ≤ Sampling frequency ≤ 250 MSPS
0.7
1.2
2
ns
tCLKRISE,
tCLKFALL
Output clock rise time,
Output clock fall time
Rise time measured from 20% to 80% of DRVDD,
Fall time measured from 80% to 20% of DRVDD,
1 MSPS ≤ Sampling frequency ≤ 150 MSPS
0.5
1
1.5
ns
tOE
Output enable (OE) to data delay
Time to valid data after OE becomes active
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
10
50%
20
ns
Timing parameters are specified by design and characterization and not tested in production.
CLOAD is the effective external single-ended load capacitance between each output pin and ground
RLOAD is the differential load resistance between the LVDS output pair.
At higher frequencies, tPDI is greater than one clock period and overall latency = ADC latency + 1.
Measurements are done with a transmission line of 100-Ω characteristic impedance between the device and the load. Setup and hold
time specifications take into account the effect of jitter on the output data and clock.
Data valid refers to logic high of +100 mV and logic low of –100 mV.
For Fs > 150 MSPS, it is recommended to use external clock for data capture and NOT the device output clock signal (CLKOUT).
Data valid refers to logic high of 1.26 V and logic low of 0.54 V.
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LVDS Timings at Lower Sampling Frequencies
SAMPLING FREQUENCY, MSPS
SETUP TIME, ns
HOLD TIME, ns
MIN
TYP
MIN
TYP
210
1.0
1.4
MAX
0.4
0.8
190
1.1
1.5
0.5
0.9
170
1.3
1.7
0.7
1.1
150
1.6
1.9
0.9
1.2
125
1.9
2.2
1.1
1.4
<100
Enable low speed mode
2.5
MAX
2.0
tPDI, ns
MIN
1 ≤ Fs ≤ 100,
Enable low speed mode
TYP
MAX
8.2
CMOS Timings at Lower Sampling Frequencies
TIMINGS SPECIFIED WITH RESPECT TO INPUT CLOCK
SAMPLING FREQUENCY, MSPS
tSTART, ns
MIN
TYP
DATA VALID TIME, ns
MAX
MIN
TYP
210
1.7
1.6
2.4
190
0.4
2.2
3.0
170
5.1
2.4
3.6
150
4.8
3.0
4.3
MAX
TIMINGS SPECIFIED WITH RESPECT TO CLKOUT
SAMPLING FREQUENCY, MSPS
SETUP TIME, ns
MIN
TYP
150
2.0
125
2.9
<100
Enable low speed mode
5.0
HOLD TIME, ns
MAX
MIN
TYP
3.2
1.5
2.2
4
2.2
2.7
MAX
3.8
tPDI, ns
MIN
1 ≤ Fs ≤ 100
Enable low speed mode
TYP
MAX
14
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N+4
N+3
N+2
N+1
Sample
N
N+20
N+19
N+18
Input
Signal
ta
Input
Clock
CLKP
CLKM
CLKOUTM
CLKOUTP
tsu
Output Data
DXP, DXM
E
E – Even Bits D0,D2,D4,...
O – Odd Bits D1,D3,D5, ...
O
E
O
N–18
E
O
N–17
E
O
N–16
E
tPDI
th
18 Clock Cycles*
DDR
LVDS
O
E
O
E
O
E
N–15
O
N
E
E
O
O
N+2
N+1
tPDI
CLKOUT
tsu
Parallel
CMOS
18 Clock Cycles*
Output Data
N–18
N–17
N–16
N–15
th
N–14
N–1
N
N+1
N+2
* This is the ADC latency. At higher sampling frequencies, tPDI > 1 clock cycle.
Then, overall latency = ADC latency + 1.
T0105-10
Figure 2. Latency Diagram
12
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Input
Clock
CLKP
CLKM
tPDI
Output
Clock
CLKOUTP
CLKOUTM
tsu
th
tsu
Output
Data Pair
(1)
(2)
Dn
Dn_Dn+1_P,
Dn_Dn+1_M
th
Dn
(1)
Dn+1
(2)
– Bits D0, D2, D4,...
Dn+1 – Bits D1, D3, D5, ...
T0106-07
Figure 3. LVDS Mode Timing
Input
Clock
CLKM
CLKP
tPDI
Output
Clock
CLKOUT
th
tsu
Output
Data
Input
Clock
Dn
Dn*
CLKM
CLKP
tSTART
tDV
Output
Data
Dn
Dn*
*Dn – Bits D0, D1, D2, ...
T0107-05
Figure 4. CMOS Mode Timing
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DEVICE CONFIGURATION
The ADS61B49/29 can be configured independently using either parallel interface control or serial interface
programming.
PARALLEL CONFIGURATION ONLY
To put the device in parallel configuration mode, keep RESET tied to high (DRVDD).
Now, pins DFS, MODE, SEN, and SDATA can be used to directly control certain modes of the ADC. The device
can be easily configured by connecting the parallel pins to the correct voltage levels (as described in Table 3 to
Table 6). There is no need to apply reset.
In this mode, SEN and SDATA function as parallel interface control pins. Frequently used functions can be
controlled in this mode – standby, selection between LVDS/CMOS output formats, 2s complement/straight binary
output format, and position of the output clock edge.
Table 1 briefly describes the modes controlled by the parallel pins.
Table 1. Parallel Pin Functions
PIN
TYPE OF
CONTROL
DFS
Analog
Data format and LVDS/CMOS output interface.
MODE
Analog
In the ADS61B49/B29, external reference is not supported. Prior use
of the MODE pin in the ADS6149/29 family is therefore not the same
in the ADS61B49/B29 family. In the next generation pin-compatible
ADC family, MODE is converted to a digital control pin for certain
reserved functions. The MODE pin can be routed to a digital controller
for possible future migration to a next generation ADC.
SEN
Analog
CLKOUT edge programmability.
SDATA
Digital
Global power down (ADC, internal references and output buffers are
powered down)
CONTROL MODES
SERIAL INTERFACE CONFIGURATION ONLY
To exercise this mode, first the serial registers have to be reset to their default values and the RESET pin has to
be kept low.
SEN, SDATA, and SCLK function as serial interface pins in this mode and can be used to access the internal
registers of the ADC.
The registers can be reset either by applying a pulse on the RESET pin or by setting the <RESET> bit (D7 in
register 0x00) high. The serial interface section describes register programming and register reset in more detail.
Since the parallel pin DFS is not to be used in this mode, it has to be tied to ground.
14
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CONFIGURATION USING BOTH THE SERIAL INTERFACE AND PARALLEL CONTROLS
For increased flexibility, an additional configuration mode is supported wherein a combination of serial interface
registers and parallel pin control (DFS) can be used to configure the device.
To exercise this mode, the serial registers have to be reset to their default values and the RESET pin has to be
kept low.
SEN, SDATA, and SCLK function as serial interface pins in this mode and can be used to access the internal
registers of ADC. The registers can be reset either by applying a pulse on the RESET pin or by setting the
<RESET> bit (D7 in register 0x00) high. The serial interface section describes register programming and register
reset in more detail.
The parallel interface control pin DFS can be used and its function is determined by the appropriate voltage
levels as described in Table 3. The voltage levels can be easily derived, by using a resistor string as illustrated
with an example as shown in Figure 5.
Since some functions can be controlled using both the parallel pins and serial registers, the priority between the
two is determined by a priority table as listed in Table 2.
Table 2. Priority Between Parallel Pins and Serial Registers
FUNCTION
Int/ext reference - not used
Data format selection
LVDS or CMOS interface selection
PRIORITY
MODE is not used in this device (legacy from the ADS6149 and future family this pin could be
redefined)
DFS pin controls this selection ONLY if the register bits <DATA FORMAT> = 00, otherwise <DATA
FORMAT> controls the selection
DFS pin controls this selection ONLY if the register bits <LVDS CMOS> = 00, otherwise <LVDS
CMOS> controls the selection
DESCRIPTION OF PARALLEL PINS
Table 3. SDATA – DIGITAL CONTROL PIN
SDATA
0
AVDD
DESCRIPTION
Normal operation (default)
Global power down. ADC, internal references and the output buffers are powered down.
Table 4. SEN – ANALOG CONTROL PIN
DESCRIPTION – OUTPUT CLOCK EDGE PROGRAMMABILITY (1)
SEN
0
(3/8)AVDD
LVDS: Setup time decreases by (4xTs/26), hold time increases by (4xTs/26)
CMOS: Setup time increases by (9xTs/26), hold time reduces by (9xTs/26)
(5/8)AVDD
LVDS: Setup time increases by (4xTs/26), hold time reduces by (4xTs/26)
CMOS: Setup time increases by (3xTs/26), hold time reduces by (3xTs/26)
AVDD
(1)
LVDS: Data and output clock transitions are aligned
CMOS: Setup time increases by (6xTs/26), hold time reduces by (6xTs/26)
Default output clock position (setup/hold timings of output data with respect to this clock position is specified in the
timing characteristics table).
Ts = 1 / sampling frequency
Table 5. DFS – ANALOG CONTROL PIN
DFS
0
DESCRIPTION
2s complement data and DDR LVDS output
(3/8)AVDD
2s complement data and parallel CMOS output
(5/8)AVDD
Offset binary data and parallel CMOS output
AVDD
Offset binary data and DDR LVDS output
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Table 6. MODE – ANALOG CONTROL PIN
MODE
DESCRIPTION
Not used
In the ADS61B49/B29, external reference is not supported. The prior use of the MODE pin in ADS6149/29 family is
therefore not the same in the ADS61B49/B29 family. In the next generation pin-compatible ADC family, MODE
could be converted to a digital control pin for certain reserved functions. The MODE pin can be routed to a digital
controller for possible future migration to a next generation ADC.
AVDD
(5/8) AVDD
3R
(5/8) AVDD
GND
AVDD
2R
(3/8) AVDD
(3/8) AVDD
3R
To Parallel Pin
GND
S0321-01
Figure 5. Simple Scheme to Configure Parallel Pins SEN and SCLK
SERIAL INTERFACE
The ADC has a set of internal registers, which can be accessed by the serial interface formed by pins SEN
(Serial interface Enable), SCLK (Serial Interface Clock) and SDATA (Serial Interface Data).
Serial shift of bits into the device is enabled when SEN is low. Serial data SDATA is latched at every falling edge
of SCLK when SEN is active (low). The serial data is loaded into the register at every 16th SCLK falling edge
when SEN is low. In case the word length exceeds a multiple of 16 bits, the excess bits are ignored. Data can be
loaded in multiples of 16-bit words within a single active SEN pulse.
The first 8 bits form the register address, and the remaining 8 bits are the register data. The interface can work
with a SCLK frequency from 20 MHz down to very low speeds (few hertz) and also with a non-50% SCLK duty
cycle.
Register Initialization
After power-up, the internal registers MUST be initialized to their default values. This can be done in one of two
ways:
1. Either through hardware reset by applying a high-going pulse on the RESET pin (of width greater than 10 ns)
as shown in Figure 6.
OR
2. By applying a software reset. Using the serial interface, set the <RESET> bit (D7 in register 0x00) to high.
This initializes the internal registers to their default values and then self-resets the <RESET> bit to low. In
this case the RESET pin is kept low.
16
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Register Data
Register Address
SDATA
A7
A6
A5
A4
A3
A2
A1
A0
D7
D6
t(SCLK)
D5
D4
D3
D2
D1
D0
t(DH)
t(DSU)
SCLK
t(SLOADH)
t(SLOADS)
SEN
RESET
T0109-01
Figure 6. Serial Interface Timing
SERIAL INTERFACE TIMING CHARACTERISTICS
Typical values at 25°C, min and max values across the full temperature range
TMIN = –40°C to TMAX = 85°C, AVDD = 3.3 V, DRVDD = 1.8 V, unless otherwise noted.
PARAMETER
MIN
> dc
TYP
MAX
UNIT
20
MHz
fSCLK
SCLK frequency (= 1/ tSCLK)
tSLOADS
SEN to SCLK setup time
25
ns
tSLOADH
SCLK to SEN hold time
25
ns
tDS
SDATA setup time
25
ns
tDH
SDATA hold time
25
ns
SERIAL REGISTER READOUT
The device includes an option where the contents of the internal registers can be read back. This may be useful
as a diagnostic check to verify the serial interface communication between the external controller and the ADC.
a. First, set register bit <SERIAL READOUT> = 1. This also disables any further writes into the registers
(EXCEPT register bit <SERIAL READOUT> itself).
b. Initiate a serial interface cycle specifying the address of the register (A7-A0) whose content has to be read.
c. The device outputs the contents (D7-D0) of the selected register on the OVR_SDOUT pin.
d. The external controller can latch the contents at the falling edge of SCLK.
e. To enable register writes, reset register bit <SERIAL READOUT> = 0.
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A) Enable serial readout (<SERIAL READOUT> = 1)
Register Data (D7:D0) = 0x01
Register Address (A7:A0) = 0x00
SDATA
0
0
0
0
0
0
0
0
D7
D6
D5
D4
D3
D2
D1
D0
SCLK
SEN
Pin OVR_SDOUT functions as OVR (<SERIAL READOUT> = 0)
OVR_SDOUT
B) Read contents of register 0x3F. This register has been initialized with 0x04 (device is put in global power down mode)
Register Data (D7:D0) = XX (Don't Care)
Register Address (A7:A0) = 0x3F
SDATA
A7
A6
A5
A4
A3
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
0
0
0
0
0
1
0
0
SCLK
SEN
OVR_SDOUT
Pin OVR_SDOUT functions as serial readout (<SERIAL READOUT> = 1)
T0386-01
Figure 7. Serial Readout
18
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RESET TIMING
Typical values at 25°C, min and max values across the full temperature range
TMIN = –40°C to TMAX = 85°C, unless otherwise noted.
PARAMETER
t1
TEST CONDITIONS
Power-on delay time
MIN
TYP
Delay from power-up of AVDD and DRVDD to RESET pulse active
t2
Reset pulse width
Pulse width of active RESET signal that resets the serial registers
t3
Delay time
Delay from RESET disable to SEN active
MAX
UNIT
1
ms
10
ns
µs
1
100
ns
Power Supply
AVDD, DRVDD
t1
RESET
t2
t3
SEN
T0108-01
Figure 8. Reset Timing Diagram
SERIAL REGISTER MAP
Table 7. Summary of Functions Supported by Serial Interface (1)
REGISTER ADDRESS
REGISTER FUNCTIONS
A7–A0 IN HEX
D7
D6
D5
D4
D3
D2
D1
D0
00
<RESET>
Software
Reset
0
0
0
0
0
0
<SERIAL
READOUT>
20
0
0
0
0
0
<ENABLE
LOW SPEED
MODE>
0
0
3F
0
0
0
<PDN
GLOBAL>
<STANDBY>
<PDN
OBUF>
0
0
0
0
0
0
0
<LVDS CMOS>
Output interface
41
0
0
52
0
0
53
0
<ENABLE OFFSET CORR>
51
0
0
0
<DATA FORMAT>
2s complement or offset
binary
0
<CUSTOM PATTERN LOW>
55
(1)
0
<CLKOUT POSN>
Output clock position control
44
50
<REF> (RESERVED)
<CUSTOM PATTERN HIGH>
0
0
0
0
0
63
0
0
0
0
<OFFSET CORR TIME CONSTANT>
Offset correction time constant
<FINE GAIN >
62
0
0
0
0
<TEST PATTERNS>
<PROGRAM OFFSET PEDESTAL >
Multiple functions in a register can be programmed in a single write operation.
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DESCRIPTION OF SERIAL REGISTERS
A)
A7–A0 IN HEX
D7
D6
D5
D4
D3
D2
D1
D0
00
<RESET>
Software Reset
0
0
0
0
0
0
<SERIAL READOUT>
D7
<RESET>
1
Software reset applied – resets all internal registers and self-clears to 0.
D0
<SERIAL READOUT>
0
Serial readout disabled
1
Serial readout enabled, pin OVR_SDOUT functions as serial data readout.
B)
A7–A0 IN HEX
20
D2
D7
D6
0
D5
0
0
D4
D3
D2
D1
D0
0
<ENABLE
LOW SPEED
MODE>
0
0
D3
D2
D1
D0
0
<PDN
GLOBAL>
<STANDBY>
<PDN
OBUF>
0
<ENABLE LOW SPEED MODE>
0
Low speed mode disabled. Use for sampling frequency > 100 MSPS
1
Enable low speed mode for sampling frequencies ≤ 100 MSPS.
C)
A7–A0 IN HEX
3F
D6,D5
D7
0
D6
D5
<REF>(RESERVED)
D4
0
<REF> RESERVED (Not used)
In the ADS61B49/61B29, external reference mode is not supported. See ADS6149/6129 non-buffered ADCs if an external
reference is required. This register controls the reference mode in those devices.
D2
<PDN GLOBAL>
0
Normal operation
1
Total power down – ADC, internal references and output buffers are powered down. Slow wake-up time.
D1
<STANDBY>
0
Normal operation
1
ADC alone powered down. Internal references, output buffers are active. Quick wake-up time
D0
<PDN OBUF> Power down output buffer
0
Output buffer enabled
1
Output buffer powered down
D)
A7–A0 IN HEX
41
D7,D6
D7
D6
<LVDS CMOS>
D5
D4
D3
D2
D1
D0
0
0
0
0
0
0
D4
D3
D2
D1
D0
0
0
<LVDS CMOS>
00
DFS pin controls LVDS or CMOS interface selection
10
DDR LVDS interface
11
Parallel CMOS interface
E)
A7–A0 IN HEX
44
20
D7
D6
D5
CLKOUT POSN> Output clock position control
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LVDS Interface
D7-D5
<CLKOUT POSN> Output clock rising edge position
000
Default output clock position (refer to timing specification table)
100
Default output clock position (refer to timing specification table)
101
Rising edge shifted by + (4/26)Ts
110
Rising edge aligned with data transition
111
Rising edge shifted by - (4/26)Ts
D4-D2
<CLKOUT POSN> Output clock falling edge position
000
Default output clock position (refer to timing specification table)
100
Default output clock position (refer to timing specification table)
101
Falling edge shifted by + (4/26)Ts
110
Falling edge aligned with data transition
111
Falling edge shifted by - (4/26)Ts
CMOS Interface
D7-D5
<CLKOUT POSN> Output clock rising edge position
000
Default output clock position (refer to timing specification table)
100
Default output clock position (refer to timing specification table)
101
Rising edge shifted by + (4/26)Ts
110
Rising edge shifted by + (6/26)Ts
111
Rising edge aligned with data transition
D4-D2
<CLKOUT POSN> Output clock falling edge position
000
Default output clock position (refer to timing specification table)
100
Default output clock position (refer to timing specification table)
101
Falling edge shifted by + (4/26)Ts
110
Falling edge shifted by + (6/26)Ts
111
Falling edge aligned with data transition
F)
A7–A0 IN HEX
D7
D6
D5
D4
D3
50
0
0
0
0
0
D5
D4
D2,D1
D2
D1
<DATA FORMAT> 2s
complement or offset binary
D0
0
<DATA FORMAT>
00
DFS pin controls data format selection
10
2s complement
11
Offset binary
G)
A7–A0 IN HEX
D7
D6
51
52
D7–D0
D3
D2
D1
D0
<Custom LOW>
<Custom HIGH>
<CUSTOM LOW>
8 lower bits of custom pattern available at the output instead of ADC data.
D5–D0
<CUSTOM HIGH>
6 upper bits of custom pattern available at the output instead of ADC data
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H)
A7–A0 IN HEX
53
D6
D7
D6
D5
D4
D3
D2
D1
D0
0
<ENABLE OFFSET CORR>
Offset correction enable
0
0
0
0
0
0
<ENABLE OFFSET CORR>
0
Offset correction disabled
1
Offset correction enabled
I)
A7–A0 IN HEX
D7
55
D7–D4
D6
<FINE GAIN>
D4
D3
D2
D1
D0
<OFFSET CORR TC> Offset correction time constant
<FINE GAIN> Gain programmability in 0.5-dB steps
0000
0-dB gain, default after reset
0001
0.5-dB gain
0010
1.0-dB gain
0011
1.5-dB gain
0100
2.0-dB gain
0101
2.5-dB gain
0110
3.0-dB gain
0111
3.5-dB gain
1000
4.0-dB gain
1001
4.5-dB gain
1010
5.0-dB gain
1011
5.5-dB gain
1100
6.0-dB gain
D3–D0
D5
<OFFSET CORR TC> Time constant of correction loop in number of clock cycles. See Offset Correction in application
section.
0000
256 k
0001
512 k
0010
1M
0011
2M
0100
4M
0101
8M
0110
16 M
0111
32 M
1000
64 M
1001
128 M
1010
256 M
1011
512 M
1100 to 1111 Reserved
22
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J)
A7–A0 IN HEX
D7
D6
D5
D4
D3
62
0
0
0
0
0
D2–D0
D2
D1
D0
<TEST PATTERNS>
<TEST PATTERNS> Test patterns to verify data capture
000
Normal operation
001
Outputs all zeros
010
Outputs all ones
011
Outputs toggle pattern
100
Outputs digital ramp
101
Outputs custom pattern
110
Unused
111
Unused
K)
A7–A0 IN HEX
D7
D6
63
0
0
D5–D0
D5
D4
D3
D2
D1
D0
<OFFSET PEDESTAL>
<OFFSET PEDESTAL> When the offset correction is enabled, the final converged value after the offset is corrected is the
ADC mid-code value.
A pedestal can be added to the final converged value by programming these bits. For example, See Offset Correction in
application section.
011111
Mid-code + 31 LSB
011110
Mid-code + 30 LSB
011101
Mid-code + 29 LSB
....
000000
Mid-code
111111
Mid-code - 1 LSB
111110
Mid-code - 2 LSB
....
100000
Mid-code - 32 LSB
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D12_D13_M
D10_D11_P
D10_D11_M
D8_D9_P
D8_D9_M
D6_D7_P
D6_D7_M
D4_D5_P
D4_D5_M
D2_D3_P
D2_D3_M
47
45
44
43
42
41
40
39
38
37
1
46
DRGND
48
D12_D13_P
DEVICE INFORMATION
Pad is connected to DRGND
36
DRGND
35
DRVDD
DRVDD
2
OVR_SDOUT
3
34
D0_D1_P
CLKOUTM
4
33
D0_D1_M
CLKOUTP
5
32
NC
DFS
6
31
NC
Thermal Pad
22
23
24
AVDD
MODE
AVDD
21
NC
AGND
20
AVDD
25
AVDD
26
12
18
11
19
CLKM
AGND
AVDD
SEN
AGND
27
17
10
AGND
CLKP
16
SDATA
INM
SCLK
28
14
29
9
15
AVDD
AGND
INP
RESET
AGND
30
8
13
7
VCM
OE
P0023-12
D10_D11_M
D8_D9_P
D8_D9_M
D6_D7_P
D6_D7_M
D4_D5_P
D4_D5_M
D2_D3_P
D2_D3_M
D0_D1_P
D0_D1_M
47
45
44
43
42
41
40
39
38
37
1
46
DRGND
48
D10_D11_P
Figure 9. PIN CONFIGURATION (LVDS MODE) — ADS61B49
Pad is connected to DRGND
36
DRGND
35
DRVDD
DRVDD
2
OVR_SDOUT
3
34
NC
CLKOUTM
4
33
NC
CLKOUTP
5
32
NC
DFS
6
31
NC
Thermal Pad
OE
7
30
RESET
22
23
24
AVDD
AVDD
21
NC
MODE
20
AVDD
AGND
18
AGND
19
AVDD
25
AVDD
26
12
AGND
11
17
CLKM
AGND
SEN
16
27
INM
10
14
CLKP
15
SDATA
INP
SCLK
28
AGND
29
9
13
8
VCM
AVDD
AGND
P0023-13
Figure 10. PIN CONFIGURATION (LVDS MODE) — ADS61B29
24
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Table 8. PIN ASSIGNMENTS (LVDS MODE) — ADS61B49 and ADS61B29
PIN
NAME
NO.
I/O
NO.
of
PINS
DESCRIPTION
AVDD
8, 18, 20,
22, 24, 26
I
6
3.3-V analog power supply
AGND
9, 12, 14,
17, 19, 25
I
6
Analog ground
CLKP, CLKM
10, 11
I
2
Differential clock input
INP, INM
15, 16
I
2
Differential analog input
13
IO
1
Internal reference mode – Common-mode voltage output.
VCM
External reference mode – Reference input. The voltage forced on this pin sets the internal
references.
Serial interface RESET input.
RESET
30
I
1
SCLK
29
I
1
When using serial interface mode, the user MUST initialize the internal registers through a
hardware RESET by applying a high-going pulse on this pin or by using the software reset option.
Refer to the SERIAL INTERFACE section.
In parallel interface mode, the user has to tie the RESET pin permanently high. (SDATA and SEN
are used as parallel pin controls in this mode.)
The pin has an internal 100-kΩ pull-down resistor.
Serial interface clock input. The pin has an internal 100-kΩ pull-down resistor.
This pin functions as the serial interface data input when RESET is low. It functions as the power-down control
pin when RESET is tied high.
SDATA
28
I
1
See Table 3 for detailed information.
The pin has an internal 100-kΩ pull-down resistor.
This pin functions as the serial interface enable input when RESET is low.
It functions as the output clock edge control when RESET is tied high. See Table 4 for detailed
information.
The pin has an internal 100-kΩ pull-up resistor to AVDD.
SEN
27
I
1
OE
7
I
1
Output buffer enable input, active high. The pin has an internal 100-kΩ pull-up resistor to DRVDD
DFS
8
I
1
Data format select input. This pin sets the data format (2s complement or offset binary) and the LVDS/CMOS
output interface type.
MODE (1)
23
I
1
Not used. See Table 6 and note below for detailed information.
CLKOUTP
5
O
1
Differential output clock, true
CLKOUTM
4
O
1
Differential output clock, complement
D0_D1_P
O
1
Differential output data D0 and D1 multiplexed, true
D0_D1_M
O
1
Differential output data D0 and D1 multiplexed, complement
D2_D3_P
O
1
Differential output data D2 and D3 multiplexed, true
D2_D3_M
O
1
Differential output data D2 and D3 multiplexed, complement
D4_D5_P
O
1
Differential output data D4 and D5 multiplexed, true
D4_D5_M
O
1
Differential output data D4 and D5 multiplexed, complement
O
1
Differential output data D6 and D7 multiplexed, true
O
1
Differential output data D6 and D7 multiplexed, complement
O
1
Differential output data D8 and D9 multiplexed, true
D8_D9_M
O
1
Differential output data D8 and D9 multiplexed, complement
D10_D11_P
O
1
Differential output data D10 and D11 multiplexed, true
D10_D11_M
O
1
Differential output data D10 and D11 multiplexed, complement
D12_D13_P
O
1
Differential output data D12 and D13 multiplexed, true
D12_D13_M
O
1
Differential output data D12 and D13 multiplexed, complement
3
O
1
It is a CMOS output with logic levels determined by the DRVDD supply. It functions as an out-of-range indicator
after a reset and when register bit <SERIAL READOUT> = 0. It functions as the serial register readout pin when
register bit <SERIAL READOUT> = 1.
DRVDD
2, 35
I
2
1.8-V digital and output buffer supply
DRGND
1, 36, PAD
I
2
Digital and output buffer ground
See Table 5 for detailed information.
D6_D7_P
D6_D7_M
D8_D9_P
OVR_SDOUT
(1)
See
Figure 9
and
Figure 10
In the next generation pin-compatible ADC family, MODE is converted to a digital control pin for certain reserved functions. So, the
selection of the internal or external reference and low speed functions are supported using MODE. In a system board using the
ADS61x9/x8, the MODE pin can be routed to a digital controller. This avoids board modification if migrating to the next generation ADC.
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ADS61B29
ADS61B49
SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008 ......................................................................................................................................... www.ti.com
Table 8. PIN ASSIGNMENTS (LVDS MODE) — ADS61B49 and ADS61B29 (continued)
PIN
NAME
NC
26
NO.
See
Figure 9
and
Figure 10
I/O
NO.
of
PINS
DESCRIPTION
Do not connect
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ADS61B29
ADS61B49
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
46
45
44
43
42
41
40
39
38
37
D13
1
48
DRGND
47
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Pad is connected to DRGND
36
DRGND
35
DRVDD
DRVDD
2
OVR_SDOUT
3
34
D1
UNUSED
4
33
D0
CLKOUT
5
32
NC
DFS
6
31
NC
Thermal Pad
22
23
24
MODE
AVDD
AGND
AVDD
25
21
12
NC
AGND
20
AVDD
AVDD
SEN
26
18
27
11
19
CLKP
CLKM
AVDD
SDATA
AGND
28
10
17
9
AGND
AGND
16
SCLK
INM
29
15
8
INP
AVDD
13
RESET
14
30
VCM
7
AGND
OE
P0023-14
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
46
45
44
43
42
41
40
39
38
37
D11
1
48
DRGND
47
Figure 11. PIN CONFIGURATION (CMOS MODE) – ADS61B49
Pad is connected to DRGND
36
DRGND
DRVDD
2
35
DRVDD
OVR_SDOUT
3
34
NC
UNUSED
4
33
NC
CLKOUT
5
32
NC
DFS
6
31
NC
Thermal Pad
23
24
MODE
AVDD
AGND
22
25
AVDD
12
21
AGND
NC
AVDD
20
26
AVDD
11
18
CLKM
19
SEN
AVDD
27
AGND
10
17
CLKP
AGND
SDATA
16
28
INM
9
15
AGND
INP
SCLK
13
RESET
29
14
30
8
VCM
7
AGND
OE
AVDD
P0023-15
Figure 12. PIN CONFIGURATION (CMOS MODE) – ADS61B29
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ADS61B49
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PIN ASSIGNMENTS (CMOS MODE) – ADS61B49 and ADS61B29
PIN
NAME
NO.
I/O
NO. of
PINS
DESCRIPTION
AVDD
8, 18, 20,
22, 24, 26
I
6
3.3-V analog power supply
AGND
9, 12, 14,
17, 19, 25
I
6
Analog ground
CLKP, CLKM
10, 11
I
2
Differential clock input
INP, INM
15, 16
I
2
Differential analog input
13
IO
1
Internal reference mode – Common-mode voltage output.
External reference mode – Reference input. The voltage forced on this pin sets the internal
references.
VCM
RESET
30
I
1
Serial interface RESET input.
When using serial interface mode, the user MUST initialize the internal registers through a
hardware RESET by applying a high-going pulse on this pin or by using the software reset
option. Refer to the SERIAL INTERFACE section.
In parallel interface mode, the user has to tie the RESET pin permanently high. (SDATA and
SEN are used as parallel pin controls in this mode.)
The pin has an internal 100-kΩ pull-down resistor.
SCLK
29
I
1
Serial interface clock input. The pin has an internal 100-kΩ pull-down resistor.
1
This pin functions as the serial interface data input when RESET is low. It functions as the
power-down control pin when RESET is tied high.
See Table 3 for detailed information.
The pin has an internal 100-kΩ pull-down resistor.
SDATA
28
I
SEN
27
I
1
This pin functions as the serial interface enable input when RESET is low.
It functions as the output clock edge control when RESET is tied high. See Table 4 for detailed
information.
The pin has an internal 100-kΩ pull-up resistor to DVDD.
DFS
8
I
1
Data format select input. This pin sets the data format (2s complement or offset binary) and the
LVDS/CMOS output interface type.
See Table 5 for detailed information.
MODE (1)
23
I
1
Not used. See Table 6 and note below for detailed information.
CLKOUT
5
O
1
CMOS output clock
OE
7
I
1
Output buffer enable input, active high. The pin has an internal 100-kΩ pull-up resistor to
DRVDD
See
Figure 11
and
Figure 12
O
14/12
3
O
1
It is a CMOS output with logic levels determined by the DRVDD supply. It functions as an
out-of-range indicator after a reset and when register bit <SERIAL READOUT> = 0. It functions
as the serial register readout pin when <SERIAL READOUT> = 1.
DRVDD
2, 35
I
2
1.8-V digital and output buffer supply
DRGND
1, 36, PAD
I
2
Digital and output buffer ground
1
Unused pin in CMOS mode
D0–D13
OVR_SDOUT
UNUSED
NC
(1)
28
4
See
Figure 11
and
Figure 12
14-bit/12-bit CMOS output data
Do not connect
In the next generation pin-compatible ADC family, MODE is converted to a digital control pin for certain reserved functions. So, the
selection of the internal or external reference and low speed functions are supported using MODE. In a system board using the
ADS61x9/x8, the MODE pin can be routed to a digital controller. This avoids board modification while migrating to the next generation
ADC.
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Product Folder Link(s): ADS61B29 ADS61B49
ADS61B29
ADS61B49
www.ti.com ......................................................................................................................................... SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008
TYPICAL CHARACTERISTICS - ADS61B49
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
FFT for 20 MHz INPUT SIGNAL
FFT for 65 MHz INPUT SIGNAL
0
0
SFDR = 91.5 dBc
SINAD = 72.5 dBFS
SNR = 72.6 dBFS
THD = 86.8 dBc
−20
Amplitude − dB
Amplitude − dB
−20
SFDR = 88.9 dBc
SINAD = 72.1 dBFS
SNR = 72.2 dBFS
THD = 84.9 dBc
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
100
f − Frequency − MHz
125
0
25
G001
Figure 13.
FFT for 170 MHz INPUT SIGNAL
100
125
G002
FFT for 300 MHz INPUT SIGNAL
0
SFDR = 80.3 dBc
SINAD = 70.2 dBFS
SNR = 70.7 dBFS
THD = 79.2 dBc
SFDR = 75.7 dBc
SINAD = 67.2 dBFS
SNR = 68.4 dBFS
THD = 72.4 dBc
−20
Amplitude − dB
−20
Amplitude − dB
75
Figure 14.
0
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
100
f − Frequency − MHz
125
0
25
G003
75
100
125
G004
Figure 16.
FFT for 2-TONE INPUT SIGNAL (IMD)
FFT for 2-TONE INPUT SIGNAL (IMD)
0
0
fIN1 = 190 MHz, –7 dBFS
fIN2 = 185 MHz, –7 dBFS
2-Tone IMD = –90 dBFS
SFDR = –95 dBFS
fIN1 = 190.1 MHz, –36 dBFS
fIN2 = 185.1 MHz, –36 dBFS
2-Tone IMD = –112 dBFS
SFDR = –99 dBFS
−20
Amplitude − dB
−20
50
f − Frequency − MHz
Figure 15.
Amplitude − dB
50
f − Frequency − MHz
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
f − Frequency − MHz
100
125
0
25
G005
Figure 17.
50
75
100
f − Frequency − MHz
125
G006
Figure 18.
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TYPICAL CHARACTERISTICS - ADS61B49 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
SFDR
vs
INPUT FREQUENCY
SNR
vs
INPUT FREQUENCY
100
100
Gain = 0 dB
Gain = 0 dB
95
92
90
88
85
SNR − dBFS
SFDR − dBc
96
84
80
76
80
75
70
72
65
68
60
64
55
60
50
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
G007
Figure 19.
Figure 20.
SFDR
vs
INPUT FREQUENCY and INTERNAL GAIN
SINAD
vs
INPUT FREQUENCY and INTERNAL GAIN
95
74
Input adjusted to get −1dBFS input
1 dB
72
2 dB
90
6 dB
85
4 dB
3 dB
80
75
0 dB
Input adjusted to get −1dBFS input
2 dB
5 dB
SINAD − dBFS
SFDR − dBc
G008
3 dB
70
0 dB
68
66
1 dB
4 dB
64
5 dB
6 dB
70
62
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
0
50
100 150 200 250 300 350 400 450 500
G009
Figure 21.
30
fIN − Input Frequency − MHz
G010
Figure 22.
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TYPICAL CHARACTERISTICS - ADS61B49 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
PERFORMANCE
vs
INPUT AMPLITUDE
PERFORMANCE
vs
INPUT COMMON-MODE VOLTAGE
85
92
76
fIN = 65 MHz
External Reference Mode
SFDR (dBFS)
75
SNR (dBFS)
60
70
40
65
SFDR (dBc)
20
88
2.10
2.15
2.20
2.25
2.30
2.35
71
2.40
VCM − Common-Mode Voltage − V
G011
G012
Figure 24.
SFDR
vs
TEMPERATURE and AVDD
SFDR
vs
TEMPERATURE and DRVDD
95
DRVDD = 1.8 V
fIN = 65 MHz
AVDD = 3.6 V
91
93
AVDD = 3.3 V
fIN = 65 MHz
AVDD = 3.5 V
89
SFDR − dBc
SFDR − dBc
2.05
Figure 23.
93
87
85
AVDD = 3.3 V
AVDD = 3.4 V
81
AVDD = 3.2 V
79
75
−40
72
82
2.00
95
77
73
SNR
84
fIN = 65 MHz
0
55
−100 −90 −80 −70 −60 −50 −40 −30 −20 −10 0
83
74
86
60
Input Amplitude − dBFS
75
SFDR
SFDR − dBc
80
90
SNR − dBFS
80
SFDR − dBc, dBFS
100
SNR − dBFS
120
AVDD = 3 V
−20
DRVDD = 1.9 V
91
DRVDD = 2 V
89
87
DRVDD = 1.7 V
AVDD = 3.1 V
0
20
DRVDD = 1.8 V
40
60
TA − Free-Air Temperature − °C
85
−40
80
−20
G013
Figure 25.
0
20
40
60
80
TA − Free-Air Temperature − °C
G014
Figure 26.
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TYPICAL CHARACTERISTICS - ADS61B49 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
SNR
vs
TEMPERATURE and AVDD
SNR
vs
TEMPERATURE and DRVDD
73.0
74.0
AVDD = 3.6 V
AVDD = 3.3 V,
AVDD = 3.5 V
AVDD = 3.3 V
fIN = 65 MHz
73.5
SNR − dBFS
SNR − dBFS
72.5
AVDD = 3 V
72.0
AVDD = 3.1 V
DRVDD = 1.7 V
73.0
DRVDD = 1.8 V
72.5
72.0
71.5
AVDD = 3.2 V,
AVDD = 3.4 V
DRVDD = 1.8 V
fIN = 65 MHz
71.0
−40
−20
0
20
40
60
TA − Free-Air Temperature − °C
71.0
−40
80
G015
20
40
60
PERFORMANCE
vs
INPUT CLOCK AMPLITUDE
PERFORMANCE
vs
INPUT CLOCK DUTY CYCLE
78
fIN = 65 MHz
80
G016
96
74
fIN = 65 MHz
77
92
73
SFDR
86
74
84
73
SNR
82
72
80
71
0.5
1.0
1.5
88
72
84
71
SNR
80
70
76
69
72
70
2.0
Input Clock Amplitude − VPP
SFDR − dBc
75
SNR − dBFS
88
SNR − dBFS
76
SFDR
SFDR − dBc
0
TA − Free-Air Temperature − °C
Figure 28.
90
78
0.0
−20
Figure 27.
94
92
DRVDD = 1.9 V,
DRVDD = 2 V
71.5
68
35
40
G017
45
50
55
Input Clock Duty Cycle − %
Figure 29.
60
65
G018
Figure 30.
OUTPUT NOISE HISTOGRAM
40
RMS (LSB) = 1.179
35
Occurence − %
30
25
20
15
10
5
0
8216 8217 8218 8219 8220 8221 8222 8223 8224 8225 8226
Output Code
G019
Figure 31.
32
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www.ti.com ......................................................................................................................................... SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008
TYPICAL CHARACTERISTICS - ADS61B29
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 DBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
FFT for 20 MHz INPUT SIGNAL
FFT for 65 MHz INPUT SIGNAL
0
0
SFDR = 91.9 dBc
SINAD = 70.3 dBFS
SNR = 70.3 dBFS
THD = 86.9 dBc
−20
Amplitude − dB
Amplitude − dB
−20
SFDR = 88.7 dBc
SINAD = 70 dBFS
SNR = 70.1 dBFS
THD = 84.8 dBc
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
100
f − Frequency − MHz
125
0
25
G020
Figure 32.
FFT for 170 MHz INPUT SIGNAL
100
125
G021
FFT for 300 MHz INPUT SIGNAL
0
SFDR = 80.1 dBc
SINAD = 68.8 dBFS
SNR = 69.1 dBFS
THD = 79 dBc
SFDR = 75.7 dBc
SINAD = 66.4 dBFS
SNR = 67.4 dBFS
THD = 72.3 dBc
−20
Amplitude − dB
−20
Amplitude − dB
75
Figure 33.
0
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
100
f − Frequency − MHz
125
0
25
G022
75
100
125
G023
Figure 35.
FFT for 2-TONE INPUT SIGNAL (IMD)
FFT for 2-TONE INPUT SIGNAL (IMD)
0
0
fIN1 = 190.1 MHz, –7 dBFS
fIN2 = 185.1 MHz, –7 dBFS
2-Tone IMD = –89.7 dBFS
SFDR = –96 dBFS
fIN1 = 190.1 MHz, –36 dBFS
fIN2 = 185.1 MHz, –36 dBFS
2-Tone IMD = –110 dBFS
SFDR = –99 dBFS
−20
Amplitude − dB
−20
50
f − Frequency − MHz
Figure 34.
Amplitude − dB
50
f − Frequency − MHz
−40
−60
−80
−100
−40
−60
−80
−100
−120
−120
0
25
50
75
f − Frequency − MHz
100
125
0
25
G024
Figure 36.
50
75
100
f − Frequency − MHz
125
G025
Figure 37.
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TYPICAL CHARACTERISTICS - ADS61B29 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 DBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
SFDR
vs
INPUT FREQUENCY
SNR
vs
INPUT FREQUENCY
100
100
Gain = 0 dB
Gain = 0 dB
95
92
90
88
85
SNR − dBFS
SFDR − dBc
96
84
80
76
80
75
70
72
65
68
60
64
55
60
50
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
G026
Figure 38.
Figure 39.
SFDR
vs
INPUT FREQUENCY and INTERNAL GAIN
SINAD
vs
INPUT FREQUENCY and INTERNAL GAIN
95
74
Input adjusted to get −1dBFS input
Input adjusted to get −1dBFS input
2 dB
90
0 dB
72
5 dB
1 dB
3 dB
SINAD − dBFS
SFDR − dBc
G027
6 dB
85
4 dB
80
0 dB
75
1 dB
2 dB
70
3 dB
68
66
4 dB
64
5 dB
6 dB
70
62
0
50
100 150 200 250 300 350 400 450 500
fIN − Input Frequency − MHz
0
50
100 150 200 250 300 350 400 450 500
G028
Figure 40.
34
fIN − Input Frequency − MHz
G029
Figure 41.
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TYPICAL CHARACTERISTICS - ADS61B29 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 DBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
PERFORMANCE
vs
INPUT AMPLITUDE
PERFORMANCE
vs
INPUT COMMON-MODE VOLTAGE
120
92
85
74
fIN = 65 MHz
External Reference Mode
SFDR (dBFS)
SNR (dBFS)
60
70
40
73
SFDR
88
SNR − dBFS
75
SFDR − dBc
80
90
SNR − dBFS
80
SFDR − dBc, dBFS
100
72
86
71
SNR
65
84
60
82
2.00
70
SFDR (dBc)
20
−60
fIN = 65 MHz
−50
−40
−30
−20
−10
0
Input Amplitude − dBFS
2.15
2.20
2.25
2.30
2.35
69
2.40
VCM − Common-Mode Voltage − V
G030
G031
Figure 43.
SFDR
vs
TEMPERATURE and AVDD
SFDR
vs
TEMPERATURE and DRVDD
95
AVDD = 3.5 V
91
DRVDD = 1.8 V
AVDD = 3.4 Vf = 65 MHz
IN
93
AVDD = 3.3 V
fIN = 65 MHz
AVDD = 3.6 V
89
DRVDD = 1.9 V
SFDR − dBc
SFDR − dBc
2.10
Figure 42.
95
93
2.05
87
85
83
AVDD = 3.3 V
91
DRVDD = 2 V
89
81
79
AVDD = 3.2 V
77
75
−40
87
AVDD = 3 V
DRVDD = 1.7 V
DRVDD = 1.8 V
AVDD = 3.1 V
−20
0
20
40
60
TA − Free-Air Temperature − °C
85
−40
80
−20
G032
Figure 44.
0
20
40
60
80
TA − Free-Air Temperature − °C
G033
Figure 45.
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TYPICAL CHARACTERISTICS - ADS61B29 (continued)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 DBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
SNR
vs
TEMPERATURE and AVDD
SNR
vs
TEMPERATURE and DRVDD
71.0
71.0
70.0
AVDD = 3 V
AVDD = 3.2 V
69.5
DRVDD = 1.8 V
70.5
SNR − dBFS
70.5
SNR − dBFS
AVDD = 3.3 V
fIN = 65 MHz
AVDD = 3.1 V, AVDD = 3.3 V,
AVDD = 3.4 V, AVDD = 3.5 V,
AVDD = 3.6 V
70.0
DRVDD = 1.7 V,
DRVDD = 1.9 V
69.5
DRVDD = 2 V
DRVDD = 1.8 V
fIN = 65 MHz
−20
0
20
40
60
TA − Free-Air Temperature − °C
20
40
60
PERFORMANCE
vs
INPUT CLOCK AMPLITUDE
PERFORMANCE
vs
INPUT CLOCK DUTY CYCLE
fIN = 65 MHz
92
72
SFDR
86
72
71
SNR
82
70
80
69
1.0
1.5
68
2.0
Input Clock Amplitude − VPP
SFDR − dBc
73
84
73
74
88
G035
fIN = 65 MHz
75
SFDR
80
96
SNR − dBFS
SFDR − dBc
G034
76
0.5
0
TA − Free-Air Temperature − °C
Figure 47.
90
78
0.0
−20
Figure 46.
94
92
69.0
−40
80
88
71
84
70
SNR
80
69
76
68
72
SNR − dBFS
69.0
−40
67
35
40
G036
45
50
55
Input Clock Duty Cycle − %
Figure 48.
60
65
G037
Figure 49.
OUTPUT NOISE HISTOGRAM
100
90
RMS (LSB) = 0.3
Occurence − %
80
70
60
50
40
30
20
10
0
2051 2052 2053 2054 2055 2056 2057 2058 2059
Output Code
G038
Figure 50.
36
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TYPICAL CHARACTERISTICS - COMMON PLOTS (Both ADS61B49/61B29)
All plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock. 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1 DBFS differential analog input, internal reference mode, 0-dB gain,
LVDS output interface (unless otherwise noted)
CMRR
vs
INPUT FREQUENCY
FFT SHOWING EFFECTS OF COMMON-MODE SIGNAL
0
0
−10
fIN = 65 MHz
fCM = 40 MHz, 140 mVpp
HD3 = 86 dBc
SNR = 68.1 dBFS
−20
Amplitude − dB
CMRR − dB
−20
−30
−40
−50
SINAD = 67.8 dBFS
THD = 82 dBc
Amp (fCM) = 86.5 dBFS
Amp (fIN + fCM) = 74.5 dBFS
Amp (fIN − fCM) = 72.3 dBFS
−40
fIN − fCM
−60
fIN + fCM
fCM
HD3
−80
−60
−100
−70
−80
−120
0
50
100
150
200
250
300
0
50
75
100
125
f − Frequency − MHz
fIN − Input Frequency − Hz
G042
G039
Figure 51.
Figure 52.
TOTAL POWER
vs
SAMPLING FREQUENCY
DRVDD CURRENT
vs
SAMPLING FREQUENCY
1.0
100
IDRVDD − DRVDD Current − mA
0.9
CMOS
CL = 10 pF
0.8
P − Total Power − W
25
0.7
LVDS
0.6
0.5
0.4
CMOS
CL = 0 pF
0.3
0.2
0.1
fIN = 3 MHz
90
80
CMOS
CL = 10 pF
70
LVDS
60
50
40
30
20
CMOS
CL = 0 pF
10
0.0
0
0
50
100
150
200
fS − Sampling Frequency − MSPS
250
0
50
G040
Figure 53.
100
150
200
250
fS − Sampling Frequency − MSPS
G041
Figure 54.
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CONTOUR PLOTS - ADS61B49/ADS61B29
Plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, sine wave input clock, 1.5-VPP differential clock amplitude, 50% clock duty
cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain, LVDS output interface (unless otherwise noted)
250
74
240
90
82
74
200
180
66
86
220
fS - Sampling Frequency - MSPS
70
78
70
90
82
160
66
78
74
86
140
120
90
70
78
66
100
82
86
80
20
50
100
74
200
150
250
350
300
400
500
450
fIN - Input Frequency - MHz
70
65
75
80
85
90
SFDR - dBc
M0049-22
Figure 55. SFDR Contour Plot (0-dB gain)
250
88
240
85
88
79
82
76
85
fS - Sampling Frequency - MSPS
220
200
76
85
180
73
85
88
82
160
88
79
85
76
140
82
120
79
91
88
100
85
80
20
50
100
150
200
250
73
76
300
350
400
450
500
fIN - Input Frequency - MHz
70
75
80
85
90
SFDR - dBc
M0049-23
Figure 56. SFDR Contour Plot (6-dB gain)
38
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CONTOUR PLOTS - ADS61B49
Plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, sine wave input clock, 1.5-VPP differential clock amplitude, 50% clock duty
cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain, LVDS output interface (unless otherwise noted)
250
240
72
220
fS - Sampling Frequency - MSPS
69
70
66
67
68
71
200
69
67
180
160
65
68
70
72
66
71
140
120
69
67
73
68
100
72
80
20
50
100
71
70
150
200
250
350
300
65
66
400
500
450
fIN - Input Frequency - MHz
64
62
66
68
70
72
74
SNR - dBFS
M0048-22
Figure 57. SNR Contour Plot (0-dB gain)
250
240
66.5
66
fS - Sampling Frequency - MSPS
65
65.5
220
64
64.5
200
180
65.5
66
66.5
160
64
64.5
67
65
140
120
64
66.5
100
67
80
20
50
66
100
200
150
250
300
64.5
65
65.5
350
400
450
500
fIN - Input Frequency - MHz
62
63
64
65
66
SNR - dBFS
67
68
M0048-23
Figure 58. SNR Contour Plot (6-dB gain)
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CONTOUR PLOTS - ADS61B29
Plots are at 25°C, AVDD = 3.3 V, DRVDD = 1.8 V, sine wave input clock, 1.5-VPP differential clock amplitude, 50% clock duty
cycle, –1 dBFS differential analog input, internal reference mode, 0-dB gain, LVDS output interface (unless otherwise noted)
250
240
69.5
69
67.5
68.5
70
65.5
65
68
220
fS - Sampling Frequency - MSPS
66
66.5
67
200
180
69.5
160
66
66.5
69
70.5
68.5
70
67.5
68
64.5
67
65
65.5
140
120
69.5
100
80
20
70.5
70
50
69
100
68
68.5
200
150
67.5
250
67
66.5
66
350
300
65
65.5
400
64.5
500
450
fIN - Input Frequency - MHz
65
64
66
68
67
69
70
71
SNR - dBFS
M0048-24
Figure 59. SNR Contour Plot (0-dB gain)
250
240
65.5
65
64
66
64.5
fS - Sampling Frequency - MSPS
220
63.5
200
180
66
64
64.5
65
65.5
160
66.5
140
120
63.5
65.5
66
66.5
65
100
64
64.5
80
20
50
100
150
200
250
300
350
400
450
500
fIN - Input Frequency - MHz
62
63
65
64
66
SNR - dBFS
67
M0048-25
Figure 60. SNR Contour Plot (6-dB gain)
40
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APPLICATION INFORMATION
THEORY OF OPERATION
The ADS61B49/29 are high performance, low power 14-bit and 12-bit A/D converters with maximum sampling
rates up to 250 MSPS. The primary difference from the ADS6149/29 is the addition of an integrated analog
buffer (hence B in the device name).
The conversion process is initiated by a rising edge of the external input clock and the analog input signal is
sampled. The sampled signal is sequentially converted by a series of small resolution stages, with the outputs
combined in a digital correction logic block. At every clock edge the sample propagates through the pipeline
resulting in a data latency of 18 clock cycles. The output is available as 14-bit/12-bit data, in DDR LVDS or
CMOS and coded in either straight offset binary or binary 2s complement format.
The dynamic offset of the first stage sub-ADC limits the maximum analog input frequency to about 500MHz (with
2-Vpp amplitude) and about 800MHz (with 1-Vpp amplitude) before the performance becomes ill-behaved. This
is separate from the full power analog bandwidth of 750MHz, which is only an indicator of signal amplitude
versus frequency.
ANALOG INPUT
The analog input consists of an integrated input buffer followed by a switched-capacitor based differential sample
and hold architecture. The addition of a buffer provides isolation from the non-linear impedance and switching
transients of the switched-capacitor circuit. With a constant input impedance, the ADC is easier to drive and to
reproduce data sheet measurements. For wide-band applications, like power amplifier linearization, the signal
gain across frequency is more consistent. Spectral performance variance across frequency is also reduced.
This differential topology results in very good ac performance even for high input frequencies at high sampling
rates. The INP and INM pins have to be externally biased around a common-mode voltage of 2.3 V, available on
the VCM pin. For a full-scale differential input, each input pin INP, INM has to swing symmetrically between
VCM+ 0.5 V and VCM – 0.5 V, resulting in a 2-Vpp differential input swing.
Lpkg
» 1 nH
5W
Buffer
INP
Cbond
» 1 pF
Ceq Buf
Resr
» 100 W
Req Buf
5 kW
2.3 V
5 kW
Lpkg
» 1 nH
Sample
and
Hold
Req Buf
Ceq Buf
5W
INM
Cbond
» 1 pF
Buffer
Resr
» 100 W
Ceq Buf (Equivalent Input Capacitance of the Buffer) = 3 pF
Req Buf » 10 W
No Capacitance Shown for Soldered-Down Package, Typically 1 pF–2 pF to Ground
S0384-01
Figure 61. Analog Input Equivalent Circuit
The input sampling circuit has a high 3-dB bandwidth that extends up to 750 MHz (measured from the input pins
to the sampled voltage).
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Drive Circuit Requirements
For optimum performance, the analog inputs must be driven differentially. This improves the common-mode
noise immunity and even-order harmonic rejection. A 5-Ω resistor in series with each input pin is recommended
to dampen out ringing caused by package parasitics.
Due to the integrated high impedance buffer in the ADS61B49/29 family, the filtering of the glitches with an
external R-C-R filter suggested for the ADS6149/29 family is not required. The drive circuit may have to be
designed to provide a low insertion loss over the desired frequency range and matched impedance to the source.
While doing this, the ADC input impedance must be considered. Figure 62 and Figure 63 show the impedance
(ZIN = RIN || CIN) looking into the ADC input pins. These figures compare the buffered ADS61B49 to the
non-buffered ADS6149.
RIN − Input Resistance − kΩ
100
10
ADS61B49
1
0.1
ADS6149
0.01
0
100
200
300
400
500
600
700
800
900
1000
f − Frequency − MHz
G081
Figure 62. ADC Analog Input Resistance Across Frequency
4.5
CIN − Input Capacitance − pF
4.0
3.5
ADS6149
3.0
2.5
2.0
1.5
ADS61B49
1.0
0.5
0.0
0
100
200
300
400
500
600
700
800
900
1000
f − Frequency − MHz
G082
Figure 63. ADC Analog Input Capacitance Across Frequency
42
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Driving Circuit
Two example driving circuit configurations are shown in Figure 64 and Figure 65 – one optimized for low input
frequencies and the other for high input frequencies. Notice in both cases that the board circuitry is simplified
compared to the non-buffered ADS6149. In Figure 64, a single transformer is used and is suited for low input
frequencies and works for some high frequency applications as well. To optimize even-harmonic performance at
high input frequencies (> 2nd Nyquist), the use of back-to-back transformers is recommended (see Figure 65).
Note that both drive circuits have been terminated by 50-Ω near the ADC side. The ac-coupling capacitors allow
the analog inputs to self-bias around the required common-mode voltage.
ADS61Bx9
0.1 mF
5W
INP
0.1 mF
25 W
25 W
INM
5W
1:1
S0381-01
Figure 64. Drive Circuit for Low Frequencies
The mismatch in the transformer parasitic capacitance (between the windings) results in degraded even-order
harmonic performance. Connecting two identical RF transformers back-to-back helps minimize this mismatch and
good performance is obtained for high frequency input signals. An additional termination resistor pair may be
required between the two transformers as shown in the figures. The center point of this termination is connected
to ground to improve the balance between the P and M sides. The values of the terminations between the
transformers and on the secondary side have to be chosen to achieve an effective 50 Ω (in the case of 50-Ω
source impedance).
ADS61Bx9
0.1 mF
5W
INP
50 W
0.1 mF
50 W
50 W
50 W
INM
1:1
1:1
5W
S0382-01
Figure 65. Drive Circuit for High Frequencies
Input Common-Mode
To ensure a low-noise common-mode reference, the VCM pin is filtered with a 0.1-µF low-inductance capacitor
connected to ground. The input common-mode voltage is nominally 2.3 V, which is 1.5 V for the ADS6149.
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REFERENCE
The ADS61B49/29 have built-in internal references REFP and REFM, requiring no external components. Design
schemes are used to linearize the converter load seen by the references; this and the on-chip integration of the
requisite reference capacitors eliminates the need for external decoupling. External reference mode is not
supported. The reference generates the VCM output (2.3 V).
Internal
Reference
VCM
REFM
REFP
S0165-10
Figure 66. Reference Section
CLOCK INPUT
The ADS61B49/29 clock inputs can be driven differentially (sine, LVPECL, or LVDS) or single-ended (LVCMOS)
with little or no difference in performance between them. The common-mode voltage of the clock inputs is set to
VCM using internal 5-kΩ resistors. This allows using transformer-coupled drive circuits for sine wave clock or
ac-coupling for LVPECL, LVDS clock sources.
44
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Clock Buffer
Lpkg
» 2 nH
20 W
CLKP
Cbond
» 1 pF
Ceq
Resr
» 100 W
Ceq
5 kW
VCM
2 pF
5 kW
Lpkg
» 2 nH
20 W
CLKM
Cbond
» 1 pF
Resr
» 100 W
Ceq » 1 to 3 pF, Equivalent Input Capacitance of Clock Buffer
S0275-04
Figure 67. Internal Clock Buffer
A single-ended CMOS clock can be ac-coupled to the CLKP input, with CLKM connected to ground with a 0.1-µF
capacitor, as shown in Figure 69. For best performance, the clock inputs have to be driven differentially, reducing
susceptibility to common-mode noise. For high input frequency sampling, it is recommended to use a clock
source with very low jitter. Band-pass filtering of the clock source can help reduce the effect of jitter. There is no
change in performance with a non-50% duty cycle clock input.
0.1 mF
0.1 mF
CMOS Clock Input
CLKP
Differential Sine-Wave
or PECL or LVDS Clock Input
CLKP
1.5 V
0.1 mF
0.1 mF
CLKM
CLKM
S0168-16
S0167-10
Figure 68. Differential Clock Driving Circuit
Figure 69. Single-Ended Clock Driving Circuit
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FINE GAIN CONTROL
The ADS61B49/29 include gain settings that can be used to get improved SFDR performance (compared to no
gain) or to reduce the required full-scale input voltage. The gain is programmable from 0 dB to 6 dB (in 0.5-dB
steps). For each gain setting, the analog input full-scale range scales proportionally, as shown in Table 9.
The SFDR improvement is achieved at the expense of SNR; for each gain setting, the SNR degrades about
0.5–1 dB. The SNR degradation is less at high input frequencies. As a result, the fine gain is useful at high input
frequencies as the SFDR improvement is significant with marginal degradation in SNR.
So, the fine gain can be used to trade-off between SFDR and SNR. Note that the default gain after reset is 0 dB.
Table 9. Full-Scale Range Across Gains
GAIN, dB
TYPE
0
Default after reset
FULL-SCALE, VPP
2V
1
1.78
2
1.59
3
4
Fine, programmable
1.42
1.26
5
1.12
6
1.00
OFFSET CORRECTION
The ADS61B49/29 have an internal offset correction algorithm that estimates and corrects the dc offset up to ±10
mV. The correction can be enabled using the serial register bit <ENABLE OFFSET CORR>. Once enabled, the
algorithm estimates the channel offset and applies the correction every clock cycle. The time constant of the
correction loop is a function of the sampling clock frequency. The time constant can be controlled using register
bits <OFFSET CORR TIME CONSTANT> as described in Table 10.
After the offset is estimated, the correction can be locked in by setting <OFFSET CORR TIME CONSTANT> = 0.
Once locked, the last estimated value is used for offset correction every clock cycle. Note that offset correction is
disabled by default after a reset.
Figure 70 shows the time response of the offset correction algorithm, after it is enabled.
Table 10. Time Constant of Offset Correction Algorithm
<OFFSET CORR TIME CONSTANT> D3-D0
TIME CONSTANT (TCCLK), NUMBER OF
CLOCK CYCLES
TIME CONSTANT, sec (TCCLK x 1/Fs) (1)
0000
256 k
1 ms
0001
512 k
2 ms
0010
1M
4 ms
0011
2M
8 ms
0100
4M
17 ms
0101
8M
33 ms
0110
16 M
67 ms
0111
32 M
134 ms
1000
64 M
268 ms
1001
128 M
536 ms
1010
256 M
1.1 s
1011
512 M
2.2 s
1100
Reserved
–
1101
Reserved
–
1110
Reserved
–
(1)
46
Sampling frequency, Fs = 250 MSPS
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Table 10. Time Constant of Offset Correction Algorithm (continued)
<OFFSET CORR TIME CONSTANT> D3-D0
TIME CONSTANT (TCCLK), NUMBER OF
CLOCK CYCLES
TIME CONSTANT, sec (TCCLK x 1/Fs) (1)
1111
Reserved
–
8204
Offset Correction Disabled
8200
Offset Correction Enabled
8196
8192
8188
Code − LSB
8184
Output Data With
Offset Corrected
8180
8176
8172
8168
Output Data With
36 LSB Offset
8164
8160
8156
8152
8148
0
4
8
12
16
20
24
28
32
36
40
44
48
52
t − Time − µs
56
G080
Figure 70. Output Code Time Response with Offset Correction Enabled
POWER DOWN
The ADS61B49/29 have three power-down modes – power-down global, standby, and output buffer disable.
Power-Down Global
In this mode, the entire chip including the A/D converter, the internal reference, and the output buffers are
powered down resulting in reduced total power dissipation of about 20 mW. The output buffers are in a high
impedance state. The wake-up time from global power down to data becoming valid in normal mode is typically
25 µs.
This can be controlled using register bit <PDN GLOBAL> or using the SDATA pin (in parallel configuration
mode).
Standby
Here, only the A/D converter is powered down and the internal references are active, resulting in a fast wake-up
time of 300 ns. The total power dissipation in standby is about 120 mW.
This can be controlled using register bit <STANDBY>.
Output Buffer Disable
The output buffers can be disabled and put in a high impedance state – wakeup time from this mode is fast,
about 40 ns. This can be controlled using register bit <PDN OBUF>.
Input Clock Stop
In addition to the above, the converter enters a low-power mode when the input clock frequency falls below 1
MSPS. The power dissipation is about 120 mW.
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POWER SUPPLY SEQUENCE
During power-up, the AVDD and DRVDD supplies can come up in any sequence. The two supplies are
separated in the device.
DIGITAL OUTPUT INFORMATION
The ADS61B49/29 provide 14-bit/12-bit data and an output clock synchronized with the data.
Output Interface
Two output interface options are available – double data rate (DDR) LVDS and parallel CMOS. They can be
selected using the serial interface register bit <ODI> or using the DFS pin in parallel configuration mode.
DDR LVDS Outputs
In this mode, the data bits and clock are output using low voltage differential signal (LVDS) levels. Two data bits
are multiplexed and output on each LVDS differential pair.
Pins
14 bit ADC data
CLKOUTP
CLKOUTM
Output Clock
D0_D1_P
D0_D1_M
Data bits D0, D1
D2_D3_P
D2_D3_M
Data bits D2, D3
D4_D5_P
D4_D5_M
Data bits D4, D5
CLKOUTP
CLKOUTM
D0_D1_P
D0_D1_M
LVDS Buffers
LVDS Buffers
Pins
Output Clock
Data bits D0, D1
P
D2_D3_
D2_D3_M
D4_D5_P
D4_D5_M
Data bits D2, D3
Data bits D4, D5
12 bit ADC data
D6_D7_P
D6_D7_P
D6_D7_M
Data bits D6, D7
D8_D9_P
D8_D9_M
Data bits D8, D9
D10_D11_P
D10_D11_M
Data bits D10, D11
D12_D13_P
D12_D13_M
Data bits D12, D13
D6_D7_M
D8_D9_P
D8_D9_M
Data bits D6, D7
Data bits D8, D9
D10_D11_P
D10_D11_M
Data bits D10, D11
ADS612X
ADS 614 X
Figure 71. 14-Bit ADC LVDS Outputs
Figure 72. 12-Bit ADC LVDS Outputs
Even data bits D0, D2, D4… are output at the falling edge of CLKOUTP, and the odd data bits D1, D3, D5… are
output at the rising edge of CLKOUTP. Both the rising and falling edges of CLKOUTP have to be used to capture
all of the data bits (see Figure 73).
48
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CLKOUTP
CLKOUTM
D0_D1_P,
D0_D1_M
D0
D1
D0
D1
D2_D3_P,
D2_D3_M
D2
D3
D2
D3
D4_D5_P,
D4_D5_M
D4
D5
D4
D5
D6_D7_P,
D6_D7_M
D6
D7
D6
D7
D8_D9_P,
D8_D9_M
D8
D9
D8
D9
D10_D11_P,
D10_D11_M
D10
D11
D10
D11
D12_D13_P,
D12_D13_M
D12
D13
D12
D13
Sample N
Sample N+1
T0110-01
Figure 73. DDR LVDS Interface
LVDS Buffer
The equivalent circuit of each LVDS output buffer is shown in Figure 74. The buffer is designed to present an
output impedance of 100 Ω (Rout). The differential outputs can be terminated at the receive end by a 100-Ω
termination. The buffer output impedance behaves like a source-side series termination. By absorbing reflections
from the receiver end, it helps to improve signal integrity. Note that this internal termination cannot be disabled
and its value cannot be changed.
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+
–
Low
0.35 V
High
SLWS214A – OCTOBER 2008 – REVISED DECEMBER 2008 ......................................................................................................................................... www.ti.com
OUTP
+
–
–0.35 V
+
–
Rout
High
1.2 V
Low
External
100-W Load
OUTM
Switch impedance is
nominally 50 W (±10%)
When the High switches are closed, OUTP = 1.375 V, OUTM = 1.025 V
When the Low switches are closed, OUTP = 1.025 V, OUTM = 1.375 V
When the High (or Low) switches are closed, Rout = 100 W
S0374-02
Figure 74. LVDS Buffer Equivalent Circuit
Parallel CMOS Interface
In CMOS mode, each data bit is output on a separate pin as a CMOS voltage level, every clock cycle. The rising
edge of the output clock CLKOUT can be used to latch data in the receiver (for sampling frequencies up to
approximately 150 MSPS).
Up to 150 MSPS, the setup and hold timings of the output data with respect to CLKOUT are specified. It is
recommended to minimize the load capacitance seen by data and clock output pins by using short traces to the
receiver. Also, match the output data and clock traces to minimize the skew between them.
For sampling frequencies > 150 MSPS in CMOS mode, it is recommended to use an external clock to capture
data. The input clock to output data delay and data valid times are specified for the higher sampling frequencies.
These timings can be used to delay the input clock appropriately and use it to capture the data (see Figure 4). It
is recommended to consider using the LVDS output mode at high sample rates due to device and board noise
generated by the CMOS mode.
50
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Pins
OVR_SDOUT
CLKOUT
D0
14-Bit ADC Data
CMOS
Output Buffers
D1
D2
•
•
•
D11
D12
D13
ADS614x
Figure 75. CMOS Output Interface
Output Buffer Strength Programmability
Switching noise (caused by CMOS output data transitions) can couple into the analog inputs during the instant of
sampling and degrade the SNR. The coupling and SNR degradation increases as the output buffer drive is made
stronger. To minimize this, the CMOS output buffers are designed with a controlled drive strength to achieve the
best SNR. The default drive strength also ensures a wide data stable window for load capacitances up to 5 pF.
CMOS Interface Power Dissipation
With CMOS outputs, the DRVDD current scales with the sampling frequency and the load capacitance on every
output pin. The maximum DRVDD current occurs when each output bit toggles between 0 and 1 every clock
cycle. In an actual application, the DRVDD current would be determined by the average number of output bits
switching, which is a function of the sampling frequency and the nature of the analog input signal.
Digital current due to CMOS output switching = CL × DRVDD × (N × FAVG),
where
CL = load capacitance,
N x FAVG = average number of output bits switching.
Figure 54 shows the current across the sampling frequencies with a 3-MHz analog input frequency.
Output Data Format
Two output data formats are supported – 2s complement and offset binary. They can be selected using the serial
interface register bit <DATA FORMAT> or controlling the DFS pin in parallel configuration mode.
In the event of an input voltage overdrive, the digital outputs go to the appropriate full-scale level. For a positive
overdrive, the output code is 0x3FFF in offset binary output format, and 0x1FFF in 2s complement output format.
For a negative input overdrive, the output code is 0x0000 in offset binary output format and 0x2000 in 2s
complement output format.
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BOARD DESIGN CONSIDERATIONS
Grounding
A single ground plane is sufficient to achieve good performance, provided the analog, digital, and clock sections
of the board are cleanly partitioned. See the EVM User Guide for details on layout and grounding.
Supply Decoupling
As the ADS61B49/29 already include internal decoupling, minimal external decoupling can be used without a
loss in performance. Note that decoupling capacitors can help filter external power supply noise, so the optimum
number of capacitors depends on the actual application. The decoupling capacitors should be placed very close
to the converter supply pins.
Exposed Pad
In addition to providing a path for heat dissipation, the pad is also electrically connected to digital ground
internally. So, it is necessary to solder the exposed pad to the ground plane for best thermal and electrical
performance.
For detailed information, see the application notes for QFN Layout Guidelines (SLOA122) and QFN/SON PCB
Attachment (SLUA271).
52
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DEFINITION OF SPECIFICATIONS
Analog Bandwidth – The analog input frequency at which the power of the fundamental is reduced by 3 dB with
respect to the low frequency value.
Aperture Delay – The delay in time between the rising edge of the input sampling clock and the actual time at
which the sampling occurs. This delay will be different across channels. The maximum variation is specified as
aperture delay variation (channel-channel).
Aperture Uncertainty (Jitter) – The sample-to-sample variation in aperture delay.
Clock Pulse Width/Duty Cycle – The duty cycle of a clock signal is the ratio of the time the clock signal remains
at a logic high (clock pulse width) to the period of the clock signal. Duty cycle is typically expressed as a
percentage. A perfect differential sine-wave clock results in a 50% duty cycle.
Maximum Conversion Rate – The maximum sampling rate at which certified operation is given. All parametric
testing is performed at this sampling rate unless otherwise noted.
Minimum Conversion Rate – The minimum sampling rate at which the ADC functions.
Differential Nonlinearity (DNL) – An ideal ADC exhibits code transitions at analog input values spaced exactly
1 LSB apart. The DNL is the deviation of any single step from this ideal value, measured in units of LSBs.
Integral Nonlinearity (INL) – The INL is the deviation of the ADC transfer function from a best fit line determined
by a least squares curve fit of that transfer function, measured in units of LSBs.
Gain Error – Gain error is the deviation of the ADC actual input full-scale range from its ideal value. The gain
error is given as a percentage of the ideal input full-scale range. Gain error has two components: error due to
reference inaccuracy and error due to the channel. Both these errors are specified independently as EGREF and
EGCHAN.
To a first order approximation, the total gain error is ETOTAL ~ EGREF + EGCHAN.
For example, if ETOTAL = ±0.5%, the full-scale input varies from (1-0.5/100) x FSideal to (1 + 0.5/100) x FSideal.
Offset Error – The offset error is the difference, given in number of LSBs, between the actual average idle
channel output code and the ideal average idle channel output code of the ADC. This quantity is often mapped
into mV.
Temperature Drift – The temperature drift coefficient (with respect to gain error and offset error) specifies the
change per degree Celsius of the parameter from TMIN to TMAX. It is calculated by dividing the maximum deviation
of the parameter across the TMIN to TMAX range by the difference TMAX–TMIN.
Signal-to-Noise Ratio – SNR is the ratio of the power of the fundamental (PS) to the noise floor power (PN),
excluding the power at DC and the first nine harmonics.
P
SNR = 10Log10 S
PN
(1)
SNR is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used as the
reference, or dBFS (dB to full scale) when the power of the fundamental is extrapolated to the full-scale range of
the converter.
Signal-to-Noise and Distortion (SINAD) – SINAD is the ratio of the power of the fundamental (PS) to the power
of all the other spectral components including noise (PN) and distortion (PD), but excluding dc.
PS
SINAD = 10Log10
PN + PD
(2)
SINAD is either given in units of dBc (dB to carrier) when the absolute power of the fundamental is used as the
reference, or dBFS (dB to full scale) when the power of the fundamental is extrapolated to the full-scale range of
the converter.
Effective Number of Bits (ENOB) – The ENOB is a measure of the converter performance as compared to the
theoretical limit based on quantization noise.
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ENOB =
SINAD - 1.76
6.02
(3)
Total Harmonic Distortion (THD) – THD is the ratio of the power of the fundamental (PS) to the power of the
first nine harmonics (PD).
P
THD = 10Log10 S
PN
(4)
THD is typically given in units of dBc (dB to carrier).
Spurious-Free Dynamic Range (SFDR) – The ratio of the power of the fundamental to the highest other
spectral component (either spur or harmonic). SFDR is typically given in units of dBc (dB to carrier).
Two-Tone Intermodulation Distortion – IMD3 is the ratio of the power of the fundamental (at frequencies f1
and f2) to the power of the worst spectral component at either frequency 2f1–f2 or 2f2–f1. IMD3 is either given in
units of dBc (dB to carrier) when the absolute power of the fundamental is used as the reference, or dBFS (dB to
full scale) when the power of the fundamental is extrapolated to the converter’s full-scale range.
DC Power Supply Rejection Ratio (DC PSRR) – The DC PSSR is the ratio of the change in offset error to a
change in analog supply voltage. The DC PSRR is typically given in units of mV/V.
AC Power Supply Rejection Ratio (AC PSRR) – AC PSRR is the measure of rejection of variations in the
supply voltage by the ADC. If ΔVSUP is the change in supply voltage and ΔVOUT is the resultant change of the
ADC output code (referred to the input), then
DVOUT
(Expressed in dBc)
PSRR = 20Log 10
DVSUP
(5)
Voltage Overload Recovery – The number of clock cycles taken to recover to less than 1% error after an
overload on the analog inputs. This is tested by separately applying a sine wave signal with 6dB positive and
negative overload. The deviation of the first few samples after the overload (from their expected values) is noted.
Common Mode Rejection Ratio (CMRR) – CMRR is the measure of rejection of variation in the analog input
common-mode by the ADC. If ΔVCM_IN is the change in the common-mode voltage of the input pins and ΔVOUT is
the resultant change of the ADC output code (referred to the input), then
DVOUT
(Expressed in dBc)
CMRR = 20Log10
DVCM
(6)
Cross-Talk (only for multi-channel ADC)– This is a measure of the internal coupling of a signal from adjacent
channel into the channel of interest. It is specified separately for coupling from the immediate neighboring
channel (near-channel) and for coupling from channel across the package (far-channel). It is usually measured
by applying a full-scale signal in the adjacent channel. Cross-talk is the ratio of the power of the coupling signal
(as measured at the output of the channel of interest) to the power of the signal applied at the adjacent channel
input. It is typically expressed in dBc.
54
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PACKAGE OPTION ADDENDUM
www.ti.com
22-Dec-2008
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
ADS61B29IRGZR
ACTIVE
QFN
RGZ
48
2500 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
ADS61B29IRGZT
ACTIVE
QFN
RGZ
48
250
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
ADS61B49IRGZR
ACTIVE
QFN
RGZ
48
2500 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
ADS61B49IRGZT
ACTIVE
QFN
RGZ
48
250
CU NIPDAU
Level-3-260C-168 HR
Green (RoHS &
no Sb/Br)
Lead/Ball Finish
MSL Peak Temp (3)
(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.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Dec-2008
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
ADS61B29IRGZR
QFN
RGZ
48
SPQ
Reel
Reel
Diameter Width
(mm) W1 (mm)
A0 (mm)
B0 (mm)
K0 (mm)
P1
(mm)
W
Pin1
(mm) Quadrant
2500
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS61B29IRGZT
QFN
RGZ
48
250
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS61B49IRGZR
QFN
RGZ
48
2500
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
ADS61B49IRGZT
QFN
RGZ
48
250
330.0
16.4
7.3
7.3
1.5
12.0
16.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Dec-2008
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
ADS61B29IRGZR
QFN
RGZ
48
2500
333.2
345.9
28.6
ADS61B29IRGZT
QFN
RGZ
48
250
333.2
345.9
28.6
ADS61B49IRGZR
QFN
RGZ
48
2500
333.2
345.9
28.6
ADS61B49IRGZT
QFN
RGZ
48
250
333.2
345.9
28.6
Pack Materials-Page 2
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