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ADS42LB49, ADS42LB69
SLAS904F – OCTOBER 2012 – REVISED MAY 2016
ADS42LBx9 14- and 16-Bit, 250-MSPS, Analog-to-Digital Converters
1 Features
2 Applications
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Dual Channel
14- and 16-Bit Resolution
Maximum Clock Rate: 250 MSPS
Analog Input Buffer with High Impedance Input
Flexible Input Clock Buffer with
Divide-by-1, -2, and -4
2-VPP and 2.5-VPP Differential Full-Scale Input
(SPI-Programmable)
DDR or QDR LVDS Interface
64-Pin VQFN Package (9-mm × 9-mm)
Power Dissipation: 820 mW/ch
Aperture Jitter: 85 fS
Internal Dither
Channel Isolation: 100 dB
Performance at fIN = 170 MHz at 2 VPP, –1 dBFS
– SNR: 73.2 dBFS
– SFDR:
– 87 dBc (HD2 and HD3)
– 100 dBc (Non HD2 and HD3)
Performance at fIN = 170 MHz:
2.5 VPP, –1 dBFS
– SNR: 74.9 dBFS
– SFDR:
– 85 dBc (HD2 and HD3)
– 97 dBc (Non HD2 and HD3)
Communication and Cable Infrastructure
Multi-Carrier, Multimode Cellular Receivers
Radar and Smart Antenna Arrays
Broadband Wireless
Test and Measurement Systems
Software-Defined and Diversity Radios
Microwave and Dual-Channel I/Q Receivers
Repeaters
Power Amplifier Linearization
3 Description
The ADS42LB49 and ADS42LB69 are a family of
high-linearity,
dual-channel,
14and
16-bit,
250-MSPS, analog-to-digital converters (ADCs)
supporting DDR and QDR LVDS output interfaces.
The buffered analog input provides uniform input
impedance across a wide frequency range while
minimizing sample-and-hold glitch energy. A
sampling clock divider allows more flexibility for
system clock architecture design. The ADS42LBx9
provides excellent spurious-free dynamic range
(SFDR) over a large input frequency range with lowpower consumption.
Device Information(1)
PART NUMBER
PACKAGE
ADS42LB49
VQFN (64)
ADS42LB69
VQFN (64)
INTERFACE OPTION
14-bit DDR or QDR LVDS
14-bit JESD204B
16-bit DDR or QDR LVDS
16-bit JESD204B
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
space
space
Simplified Schematic
ADS42LB49, ADS42LB69
14-, 16-Bit
ADC
CLKINP,
CLKINM
Output
Formatter
Digital Gain
and Test
Patterns
QDR
LVDS
Divide
by 1,2,4
SYNCINP,
SYNCINM
DACLKP,
DACLKM
Fs = 250Msps
Fin = 170MHz
Ain = -1dBFS
HD2 = 90dBc
HD3 = 89dBc
Non HD2,3 = 100dBc
-20
DA[3:0]P,
DA[3:0]M
-40
Delay
DB[3:0]P,
B[3:0]MM
Digital
Block
14-, 16-Bit
ADC
INBP,
INBM
0
DAFRAMEP,
AFRAMEM
Output
Formatter
Digital Gain
and Test
Patterns
QDR
LVDS
DBCLKP,
BCLKM
DBFRAMEP,
BFRAMEM
Amplitude (dB)
INAP,
INAM
FFT for 170MHz Input Signal
OVRA
Digital
Block
-60
-80
OVRB
VCM
Common
Mode
Configuration
Registers
CTRL1
CTRL2
SDOUT
SEN
SCLK
SDATA
RESET
-100
Copyright © 2016, Texas Instruments Incorporated
-120
0
25
50
75
Frequency (MHz)
100
125
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.
ADS42LB49, ADS42LB69
SLAS904F – OCTOBER 2012 – REVISED MAY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
6.13
6.14
6.15
7
1
1
1
2
4
9
Absolute Maximum Ratings ...................................... 9
ESD Ratings.............................................................. 9
Recommended Operating Conditions..................... 10
Thermal Information ................................................ 10
Electrical Characteristics: ADS42LB69 (16-Bit) ...... 11
Electrical Characteristics: ADS42LB49 (14-Bit) ...... 12
Electrical Characteristics: General .......................... 13
Digital Characteristics ............................................. 14
Timing Requirements: General ............................... 15
Timing Requirements: DDR LVDS Mode.............. 15
Timing Requirements: QDR LVDS Mode ............ 16
Typical Characteristics: ADS42LB69 .................... 17
Typical Characteristics: ADS42LB49 .................... 22
Typical Characteristics: Common ......................... 27
Typical Characteristics: Contour ........................... 28
Parameter Measurement Information ................ 31
8
Detailed Description ............................................ 34
8.1
8.2
8.3
8.4
8.5
8.6
9
Overview .................................................................
Functional Block Diagrams .....................................
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
Register Maps .........................................................
34
34
35
40
43
47
Application and Implementation ........................ 60
9.1 Application Information............................................ 60
9.2 Typical Application .................................................. 60
10 Power Supply Recommendations ..................... 67
11 Layout................................................................... 67
11.1 Layout Guidelines ................................................. 67
11.2 Layout Example .................................................... 68
12 Device and Documentation Support ................. 70
12.1
12.2
12.3
12.4
12.5
Related Links ........................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
70
70
70
70
70
13 Mechanical, Packaging, and Orderable
Information ........................................................... 70
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision E (December 2014) to Revision F
Page
•
Added Using the ADS42LBx9 In Time-Domain, Low-Frequency Pulse Applications section.............................................. 63
•
Added Community Resources section ................................................................................................................................ 70
Changes from Revision D (September 2013) to Revision E
Page
•
Added ESD Ratings table and Feature Description, Device Functional Modes, Application and
Implementation, Power Supply Recommendations, Layout, Device and Documentation Support, and Mechanical,
Packaging, and Orderable Information sections..................................................................................................................... 1
•
Deleted Ordering Information section..................................................................................................................................... 4
•
Merged all Pin Functions tables into one table ...................................................................................................................... 7
•
Changed INAP, INAM pin numbers for ADS42LB69 and ADS42LB49 DDR LVDS in pin assignments table ...................... 7
•
Added footnote to Table 1 ................................................................................................................................................... 15
•
Added footnote to Table 2 ................................................................................................................................................... 16
•
Changed pin 34 to pin 37 in Figure 79 ................................................................................................................................ 36
Changes from Revision C (September 2013) to Revision D
Page
•
Changed device status to Production Data ............................................................................................................................ 1
•
Added pre-RTM changes throughout document .................................................................................................................... 1
2
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Changes from Revision B (March 2013) to Revision C
•
Page
Added pre-RTM changes throughout document .................................................................................................................... 1
Changes from Revision A (November 2012) to Revision B
•
Page
Added pre-RTM changes throughout document .................................................................................................................... 1
Changes from Original (October 2012) to Revision A
•
Page
Added pre-RTM changes throughout document .................................................................................................................... 1
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Product Folder Links: ADS42LB49 ADS42LB69
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5 Pin Configuration and Functions
49 DRVDD
50 DA10M
51 DA10P
52 DA12M
53 DA12P
54 DA14M
55 DA14P
56 CLKOUTM
57 CLKOUTP
58 DB14M
59 DB14P
60 DB12M
61 DB12P
62 DB10P
DB8M
1
48
DB8P
2
47 DA8M
DB6M
3
46 DA6P
DB6P
4
45 DA6M
DB4M
5
44 DA4P
DB4P
6
43 DA4M
DB2M
7
42 DA2P
DB2P
8
41 DA2M
DB0M
9
40 DA0P
DA8P
DB0P
10
39 DA0M
DRVDD
11
38 AVDD
CTRL2
12
37 CTRL1
AVDD
13
36 AVDD
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32
AVDD3V
AVDD 31
SYNCINM 30
SYNCINP 29
RESERVED 28
VCM 27
AVDD 26
CLKINP 25
AVDD 23
33 AVDD
CLKINM 24
16
RESET 22
AVDD
SDOUT 21
34 INAM
SEN 20
35 INAP
SDATA 19
14
15
SCLK 18
INBP
INBM
AVDD3V 17
4
63 DB10P
64 DRVDD
ADS42LB69 DDR LVDS: RGC Package
64-Pin VQFN
Top View
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
49 DRVDD
50 DA8M
51 DA8P
52 DA10M
53 DA10P
54 DA12M
55 DA12P
56 CLKOUTM
57 CLKOUTP
58 DB12M
59 DB12P
60 DB10M
61 DB10P
62 DB8P
63 DB8P
64 DRVDD
ADS42LB49 DDR LVDS: RGC Package
64-Pin VQFN
Top View
DB6M
1
48
DB6P
2
47 DA6M
DB4M
3
46 DA4P
DB4P
4
45 DA4M
DB2M
5
44 DA2P
DB2P
6
43 DA2M
DB0M
7
DA6P
42 DA0P
GND Pad (Backside)
DB0P
8
NC/OVR
9
40 NC/OVR
NC/OVR
10
39 NC/OVR
DRVDD
11
38 AVDD
CTRL2
12
37 CTRL1
AVDD
13
36 AVDD
41 DA0M
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32
AVDD 31
AVDD3V
SYNCINP 29
SYNCINM 30
RESERVED 28
VCM 27
AVDD 26
CLKINP 25
CLKINM 24
AVDD 23
33 AVDD
RESET 22
16
SEN 20
AVDD
SDOUT 21
34 INAM
SDATA 19
35 INAP
SCLK 18
14
15
AVDD3V 17
INBP
INBM
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49 DRVDD
50 DA3M
51 DA3P
52 DAFRAMEM
53 DAFRAMEM
54 OVRA
55 NC
56 NC
57 NC
58 NC
59 OVRB
60 NC
61 NC
62 DB0M
DB1M
1
48
DA2P
DB1P
2
47 DA2M
DBCLKM
3
46 DACLKP
DBCLKP
4
45 DACLKM
DB2M
5
44 DA1P
DB2P
6
43 DA1M
DB3M
7
42 DA0P
DB3P
8
GND Pad (Backside)
41 DA0M
AVDD
16
33 AVDD
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AVDD3V
32
34 INAM
AVDD 31
15
SYNCINM 30
INBM
SYNCINP 29
35 INAP
VCM 27
36 AVDD
14
RESERVED 28
13
INBP
AVDD 26
AVDD
CLKINP 25
37 CTRL1
AVDD 23
38 AVDD
12
CLKINM 24
11
CTRL2
RESET 22
DRVDD
SDOUT 21
39 NC
SEN 20
40 NC
10
SDATA 19
9
DBFRAMEP
SCLK 18
DBFRAMEM
AVDD3V 17
6
63 DB0P
64 DRVDD
ADS42LB69, ADS42LB49 QDR LVDS: RGC Package
64-Pin VQFN
Top View
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Pin Functions
PIN
I/O
DESCRIPTION
ADS42LB69
DDR LVDS
ADS42LB49
DDR LVDS
QDR LVDS
INAP, INAM
35, 34
35, 34
34, 35
I
Differential analog input for channel A
INBP, INBM
14, 15
14, 15
14, 15
I
Differential analog input for channel B
27
27
27
O
Common-mode voltage for analog inputs, 1.9 V
CLKINP, CLKINM
25, 24
25, 24
24, 25
I
Differential clock input for ADC
SYNCINP, SYNCINM
29, 30
29, 30
29, 30
I
External sync input. If not used, connect SYNCINP to GND and SYNCINM to
AVDD.
CTRL1
37
37
37
I/O
Can be configured as power-down input pin or as OVR output pin for channel A,
depending on the register bit PDN/OVR FOR CTRL PINS.
CTRL2
12
12
12
I/O
Can be configured as power-down input pin or as OVR output pin for channel B,
depending on the register bit PDN/OVR FOR CTRL PINS
NC
—
—
39, 40, 55-58, 60,
61
—
Do not connect
NC/OVR
—
9, 10, 39, 40
—
—
If the OVR ON LSB bit is set, these pins can be used because they carry
overrange information. Otherwise, do not connect these pins.
Reserved
28
28
28
—
Do not connect
RESET
22
22
22
I
Hardware reset. Active high.
SCLK
18
18
18
I
Serial interface clock input
SDATA
19
19
19
I
Serial interface data input
SDOUT
21
21
21
O
Serial interface data output
SEN
20
20
20
I
Serial interface enable
57, 56
57, 56
—
O
Differential LVDS output clock
—
—
41-44, 47, 48, 50,
51
O
4-bit QDR LVDS output interface for channel A
39-48, 50-55
41-48, 50-55
—
O
DDR LVDS output interface for channel A
DACLKP, DACLKM
—
—
45, 46
O
Differential output clock for channel A
DAFRAMEP, DAFRAMEM
—
—
52, 53
—
Differential frame clock output for channel A
DB[3:0]P, DB[3:0]M
—
—
1, 2, 5-8, 62, 63
—
4-bit QDR LVDS output interface for channel B
1-10, 58-63
1-8, 58-63
—
O
DDR LVDS output interface for channel B
DBCLKP, DBCLKM
—
—
3, 4
—
Differential output clock for channel A
DBFRAMEP, DBFRAMEM
—
—
9, 10
—
Differential frame clock output for channel A
NAME
INPUT AND REFERENCE
VCM
CLOCK AND SYNC
CONTROL AND SERIAL
DATA INTERFACE
CLKOUTP, CLKOUTM
DA[3:0]P, DA[3:0]M
DA[14:0]P, DA[14:0]M
DB[14:0]P, DB[14:0]M
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Pin Functions (continued)
PIN
I/O
DESCRIPTION
ADS42LB69
DDR LVDS
ADS42LB49
DDR LVDS
QDR LVDS
OVRA
—
—
54
O
Overrange indication channel A
OVRB
—
—
59
O
Overrange indication channel A
13, 16, 23, 26, 31,
33, 36, 38
13, 16, 23, 26, 31,
33, 36, 38
13, 16, 23, 26, 31,
33, 36, 38
I
Analog 1.8-V power supply
NAME
POWER SUPPLY
AVDD
AVDD3V
17, 32
17, 32
17, 32
I
Analog 3.3 V power supply for analog buffer
DRVDD
11, 49, 64
11, 49, 64
11, 49, 64
I
Digital 1.8-V power supply
Ground pad
Ground pad
Ground pad
I
Ground
GND
8
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
Supply voltage
MIN
MAX
AVDD3V
–0.3
3.6
AVDD
–0.3
2.1
DRVDD
–0.3
2.1
–0.3
0.3
Voltage between AGND and DGND
Voltage applied to input pins
Temperature
INA, INBP, INA, INBM
–0.3
3
CLKINP, CLKINM
–0.3
AVDD + 0.3
SYNCINP, SYNCINM
–0.3
AVDD + 0.3
SCLK, SEN, SDATA, RESET, CTRL1, CTRL2
–0.3
3.9
Operating free-air, TA
–40
+85
Operating junction, TJ
Storage, Tstg
(1)
UNIT
V
V
V
+125
–65
°C
+150
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
V(ESD)
(1)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
VALUE
UNIT
±2000
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
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6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted) (1)
MIN
NOM
MAX
UNIT
SUPPLIES
AVDD
Analog supply voltage
AVDD3V
Analog buffer supply voltage
DRVDD
Digital supply voltage
1.7
1.8
1.9
V
3.15
3.3
3.45
V
1.7
1.8
1.9
V
ANALOG INPUTS
VID
Differential input voltage range
VICR
Input common-mode voltage
Default after reset
2
Register programmable (2)
VPP
2.5
VCM ± 0.025
V
Maximum analog input frequency with 2.5-VPP input amplitude
250
MHz
Maximum analog input frequency with 2-VPP input amplitude
400
MHz
CLOCK INPUT
Input clock sample rate
QDR interface
30
250
DDR interface
10
250
0.3 (3)
Sine wave, ac-coupled
Input clock amplitude differential
(VCLKP – VCLKM)
1.5
LVPECL, ac-coupled
1.6
LVDS, ac-coupled
0.7
LVCMOS, single-ended, ac-coupled
1.5
Input clock duty cycle
35%
MSPS
50%
VPP
V
65%
DIGITAL OUTPUTS
CLOAD
Maximum external load capacitance from each output pin to DRGND
RLOAD
Single-ended load resistance
TA
Operating free-air temperature
(1)
(2)
(3)
3.3
pF
Ω
+50
–40
+85
°C
After power-up, to reset the device for the first time, only use the RESET pin. Refer to the Register Initialization section.
For details, refer to the Digital Gain section.
Refer to the Performance vs Clock Amplitude curves, Figure 27 and Figure 28.
6.4 Thermal Information
ADS42LBx9
THERMAL METRIC
(1)
RGC (VQFN)
UNIT
64 PINS
RθJA
Junction-to-ambient thermal resistance
22.9
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
7.1
°C/W
RθJB
Junction-to-board thermal resistance
2.5
°C/W
ψJT
Junction-to-top characterization parameter
0.1
°C/W
ψJB
Junction-to-board characterization parameter
2.5
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
0.2
°C/W
(1)
10
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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6.5 Electrical Characteristics: ADS42LB69 (16-Bit)
Typical values are at TA = +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS
differential analog input, and sampling rate = 250 MSPS, unless otherwise noted. Minimum and maximum values are across
the full temperature range of TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V.
PARAMETER
SNR
SINAD
Signal-to-noise ratio
Signal-to-noise and distortion ratio
TEST CONDITIONS
2-VPP FULL-SCALE
MIN
SFDR
THD
HD2
HD3
Total harmonic distortion
2nd-order harmonic distortion
3rd-order harmonic distortion
Worst spur
(other than second and third
harmonics)
Two-tone intermodulation distortion
MIN
TYP
73.9
75.8
fIN = 70 MHz
73.7
75.5
73.2
74.7
fIN = 230 MHz
72.8
74.1
fIN = 10 MHz
73.7
75.1
fIN = 70 MHz
73.6
75.3
73.1
74.2
fIN = 170 MHz
fIN = 170 MHz
70.8
69.6
72.5
73.4
fIN = 10 MHz
87
83
fIN = 70 MHz
90
88
87
85
fIN = 230 MHz
86
83
fIN = 10 MHz
86
82
fIN = 70 MHz
89
87
85
82
fIN = 230 MHz
83
81
fIN = 10 MHz
97
95
fIN = 70 MHz
90
88
87
85
fIN = 230 MHz
86
84
fIN = 10 MHz
87
83
fIN = 70 MHz
96
94
91
85
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
81
78
81
81
fIN = 230 MHz
87
83
fIN = 10 MHz
102
103
101
103
101
101
fIN = 70 MHz
fIN = 170 MHz
fIN = 230 MHz
IMD
MAX
fIN = 10 MHz
fIN = 230 MHz
Spurious-free dynamic range
(including second and third harmonic
distortion)
TYP
2.5-VPP FULL-SCALE
87
MAX
UNIT
dBFS
dBFS
dBc
dBc
dBc
dBc
dBc
100
100
f1 = 46 MHz, f2 = 50 MHz,
each tone at –7 dBFS
97
94
f1 = 185 MHz, f2 = 190 MHz,
each tone at –7 dBFS
94
90
100
100
1
1
> 40
> 40
dB
dBFS
Crosstalk
20-MHz, full-scale signal on channel
under observation;
170-MHz, full-scale signal on other
channel
Input overload recovery
Recovery to within 1% (of full-scale) for
6-dB overload with sine-wave input
PSRR
AC power-supply rejection ratio
For 50-mVPP signal on AVDD supply,
up to 10 MHz
ENOB
Effective number of bits
fIN = 170 MHz
11.85
12.03
LSBs
DNL
Differential nonlinearity
fIN = 170 MHz
±0.6
±0.6
LSBs
INL
Integrated nonlinearity
fIN = 170 MHz
±3
±3.5
LSBs
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Clock
cycle
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6.6 Electrical Characteristics: ADS42LB49 (14-Bit)
Typical values are at TA = +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS
differential analog input, and sampling rate = 250 MSPS, unless otherwise noted. Minimum and maximum values are across
the full temperature range of TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V.
PARAMETER
SNR
SINAD
SFDR
THD
HD2
HD3
Signal-to-noise ratio
Signal-to-noise and distortion ratio
Spurious-free dynamic range
(including second and third harmonic
distortion)
Total harmonic distortion
2nd-order harmonic distortion
3rd-order harmonic distortion
Worst spur
(other than second and third
harmonics)
IMD
Two-tone intermodulation distortion
TEST CONDITIONS
2-VPP FULL-SCALE
MIN
TYP
2.5-VPP FULL-SCALE
MAX
MIN
TYP
fIN = 10 MHz
73.3
74.9
fIN = 70 MHz
73.1
74.7
72.7
74.1
fIN = 230 MHz
72.3
73.5
fIN = 10 MHz
73.1
74.1
fIN = 70 MHz
73.1
74.4
72.6
73.6
fIN = 230 MHz
72
72.9
fIN = 10 MHz
87
82
fIN = 70 MHz
90
88
87
85
fIN = 230 MHz
86
83
fIN = 10 MHz
86
81
fIN = 70 MHz
89
87
85
82
fIN = 230 MHz
83
81
fIN = 10 MHz
97
95
fIN = 70 MHz
90
88
87
85
fIN = 230 MHz
86
84
fIN = 10 MHz
87
82
fIN = 70 MHz
96
94
91
85
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
fIN = 170 MHz
69.5
68.5
79
76
79
79
MAX
UNIT
dBFS
dBFS
dBc
dBc
dBc
dBc
fIN = 230 MHz
87
83
fIN = 10 MHz
104
103
101
103
100
101
fIN = 230 MHz
99
100
f1 = 46 MHz, f2 = 50 MHz,
each tone at –7 dBFS
99
95
f1 = 185 MHz, f2 = 190 MHz,
each tone at –7 dBFS
93
93
100
90
dB
Clock
cycle
fIN = 70 MHz
fIN = 170 MHz
87
dBc
dBFS
Crosstalk
20-MHz, full-scale signal on channel
under observation;
170-MHz, full-scale signal on other
channel
Input overload recovery
Recovery to within 1% (of full-scale) for
6-dB overload with sine-wave input
1
1
PSRR
AC power-supply rejection ratio
For a 50-mVPP signal on AVDD supply,
up to 10 MHz
> 40
> 40
dB
ENOB
Effective number of bits
fIN = 170 MHz
11.76
11.93
LSBs
DNL
Differential nonlinearity
fIN = 170 MHz
±0.15
±0.15
LSBs
INL
Integrated nonlinearity
fIN = 170 MHz
±0.75
±0.9
LSBs
12
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6.7 Electrical Characteristics: General
Typical values are at +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS differential
analog input, and sampling rate = 250 MSPS, unless otherwise noted. Minimum and maximum values are across the full
temperature range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ANALOG INPUTS
VID
Default (after reset)
Differential input voltage range
2
2.5
Differential input resistance (at 170 MHz)
1.2
kΩ
4
pF
Differential input capacitance (at 170 MHz)
With 50-Ω source impedance, and 50-Ω
termination
Analog input bandwidth
VCM
VPP
Register programmed (1)
900
MHz
Common-mode output voltage
1.9
V
VCM output current capability
10
mA
DC ACCURACY
Offset error
–20
EGREF
Gain error as a result of internal reference
inaccuracy alone
EGCHAN
Gain error of channel alone
20
mV
±2
%FS
–5
Temperature coefficient of EGCHAN
%FS
Δ%/°C
0.01
POWER SUPPLY
IAVDD
Analog supply current
141
182
mA
IAVDD3V
Analog buffer supply current
302
340
mA
219
245
mA
IDRVDD
Digital and output buffer supply current
External 100-Ω differential termination on
LVDS outputs
Analog power
253
mW
Analog buffer power
996
mW
393
mW
Power consumption (includes digital blocks
and output buffers)
External 100-Ω differential termination on
LVDS outputs
Total power
1.64
Global power-down (both channels)
(1)
1.85
W
160
mW
Refer to the Serial Interface section.
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6.8 Digital Characteristics
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 = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, and, unless otherwise noted.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DIGITAL INPUTS (RESET, SCLK, SDATA, SEN, CTRL1, CTRL2) (1)
VIH
High-level input voltage
VIL
Low-level input voltage
IIH
High-level input current
All digital inputs support 1.8-V and
3.3-V CMOS logic levels
RESET, SDATA, SCLK,
CTRL1, CTRL2 (2)
Low-level input current
V
0.4
VHIGH = 1.8 V
10
VHIGH = 1.8 V
0
RESET, SDATA, SCLK,
CTRL1, CTRL2
VLOW = 0 V
0
SEN
VLOW = 0 V
10
SEN
IIL
1.3
(3)
V
µA
µA
DIGITAL OUTPUTS, CMOS INTERFACE (OVRA, OVRB, SDOUT)
VOH
High-level output voltage
VOL
Low-level output voltage
DRVDD – 0.1
DRVDD
V
0
0.1
V
DIGITAL OUTPUTS, LVDS INTERFACE
VODH
High-level output differential voltage
With an external
100-Ω termination
250
350
500
mV
VODL
Low-level output differential voltage
With an external
100-Ω termination
–500
–350
–250
mV
VOCM
Output common-mode voltage
(1)
(2)
(3)
14
1.05
V
SCLK, SDATA, and SEN function as digital input pins in serial configuration mode.
SDATA and SCLK have an internal 150-kΩ pull-down resistor.
SEN has an internal 150-kΩ pull-up resistor to AVDD. Because the pull-up resistor is weak, SEN can also be driven by 1.8-V or 3.3-V
CMOS buffers.
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6.9 Timing Requirements: General
Typical values are at +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, sampling frequency = 250 MSPS, sine wave
input clock, CLOAD = 3.3 pF, and RLOAD = 100 Ω, unless otherwise noted. Minimum and maximum values are across the full
temperature range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.7 V to 1.9 V.
MIN
tA
Aperture delay
MAX
0.7
1.1
0.5
Aperture delay matching between two channels of the same device
ps
ps
85
Time to valid data after coming out of STANDBY mode
Time to valid data after coming out of GLOBAL power-down
mode (in this mode, both channels power-down)
ADC latency (1)
ns
±150
Aperture jitter
Wakeup time
UNIT
±70
Variation of aperture delay between two devices at the same temperature and supply voltage
tJ
TYP
fS rms
50
100
µs
250
1000
µs
Default latency after reset
14
Clock cycles
Normal OVR latency
14
Clock cycles
9
Clock cycles
Fast OVR latency
tSU_SYNCIN
Setup time for SYNCIN, referenced to input clock rising edge
400
ps
tH_SYNCIN
Hold time for SYNCIN, referenced to input clock rising edge
100
ps
(1)
Overall latency = ADC latency + tPDI.
6.10 Timing Requirements: DDR LVDS Mode (1)
Typical values are at +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, sampling frequency = 250 MSPS, sine wave
input clock, CLOAD = 3.3 pF, and RLOAD = 100 Ω, unless otherwise noted. Minimum and maximum values are across the full
temperature range: TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, and DRVDD = 1.7 V to 1.9 V.
MIN
TYP
MAX
UNIT
tSU
Data setup time: data valid to zero-crossing of differential output clock
(CLKOUTP – CLKOUTM) (2)
0.62
0.82
ns
tHO
Data hold time: zero-crossing of differential output clock (CLKOUTP – CLKOUTM) to
data becoming invalid (2)
0.54
0.64
ns
tPDI
Clock propagation delay: input clock rising edge cross-over to output clock
(CLKOUTP – CLKOUTM) rising edge cross-over
8
10.5
13
ns
LVDS bit clock duty cycle: duty cycle of differential clock (CLKOUTP – CLKOUTM)
52%
tFALL,
tRISE
Data fall time, data rise time: rise time measured from –100 mV to +100 mV,
10 MSPS ≤ sampling frequency ≤ 250 MSPS
0.14
ns
tCLKRISE,
tCLKFALL
Output clock rise time, output clock fall time: Rise time measured from
–100 mV to +100 mV, 10 MSPS ≤ sampling frequency ≤ 250 MSPS
0.18
ns
(1)
(2)
Measurements are done with a transmission line of a 100-Ω characteristic impedance between the device and load. Setup and hold time
specifications take into account the effect of jitter on the output data and clock.
Data valid refers to a logic high of +100 mV and a logic low of –100 mV.
Table 1. DDR LVDS Timings at Lower Sampling Frequencies (1)
SETUP TIME
(1)
SAMPLING
FREQUENCY
(MSPS)
MIN
TYP
CLOCK PROPAGATION
DELAY
HOLD TIME
tSU
tHO
MAX
MIN
TYP
tPDI
MAX
MIN
TYP
MAX
80
2.40
2.96
2.16
2.82
9
11.9
15
120
1.57
1.92
1.40
1.84
8
11.1
14
160
1.17
1.40
1.02
1.36
8
10.6
13
200
0.82
1.07
0.72
1.02
8
10.5
13
230
0.69
0.91
0.61
0.84
8
10.5
13
UNIT
ns
See Figure 73 for a timing diagram in DDR LVDS mode.
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6.11 Timing Requirements: QDR LVDS Mode (1) (2)
Typical values are at +25°C, AVDD = 1.8 V, AVDD3V = 3.3 V, DRVDD = 1.8 V, sampling frequency = 250 MSPS, sine-wave
input clock, CLOAD = 3.3 pF (3), and RLOAD = 100 Ω (4), unless otherwise noted. Minimum and maximum values are across the
full temperature range of TMIN = –40°C to TMAX = +85°C, AVDD = 1.8 V, AVDD3V = 3.3 V, and DRVDD = 1.7 V to 1.9 V.
(5) (6)
tSU
Data setup time
tH
Data hold time (5) (6): DxCLKP, DxCLKM zero-crossing to data becoming invalid
: data valid to DxCLKP, DxCLKM zero-crossing
MIN
TYP
0.23
0.31
ns
0.16
0.29
ns
LVDS bit clock duty cycle: differential bit clock duty cycle (DxCLKP, DxCLKM)
tPDI
Clock propagation delay: input clock rising edge cross-over to output frame clock
(DxFRAMEP-DxFRAMEM) rising edge cross-over
tRISE,
tFALL
Data rise and fall time: rise time measured from –100 mV to +100 mV
tCLKRISE,
tCLKFALL
Output clock rise and fall time: rise time measured from –100 mV to +100 mV
(1)
(2)
(3)
(4)
(5)
(6)
MAX
UNIT
50%
7
10.1
13
ns
0.18
ns
0.2
ns
Measurements are done with a transmission line of 100-Ω characteristic impedance between the device and load. Setup and hold time
specifications take into account the effect of jitter on the output data and clock.
Timing parameters are ensured by design and characterization and are 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.
Data valid refers to a logic high of +100 mV and a logic low of –100 mV.
The setup and hold times of a channel are measured with respect to the same channel output clock.
Table 2. QDR LVDS Timings at Lower Sampling Frequencies (1)
(1)
16
SETUP TIME
HOLD TIME
CLOCK PROPAGATION
DELAY
tSU
tHO
tPDI
SAMPLING
FREQUENCY
(MSPS)
MIN
TYP
MIN
TYP
MIN
TYP
MAX
80
1.06
1.21
0.84
1.29
6
9.3
12
120
0.63
0.77
0.66
0.88
7
9.5
13
160
0.43
0.55
0.39
0.61
7
9.7
13
200
0.31
0.42
0.28
0.47
7
9.8
13
230
0.24
0.34
0.17
0.36
7
9.9
13
MAX
MAX
UNIT
ns
See Figure 74 for a timing diagram in QDR LVDS mode.
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6.12 Typical Characteristics: ADS42LB69
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, QDR interface, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point
FFT, unless otherwise noted.
0
0
fIN = 10 MHz
SFDR = 88 dBc
SNR = 74 dBFS
SINAD = 73.9 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 102 dBc
−40
−60
−20
Amplitude (dBFS)
Amplitude (dBFS)
−20
−80
−100
−120
fIN = 170 MHz
SFDR = 90 dBc
SNR = 73.1 dBFS
SINAD = 73 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 100 dBc
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
Figure 1. FFT for 10-MHz Input Signal
fIN = 300 MHz
SFDR = 76 dBc
SNR = 72.2 dBFS
SINAD = 70.5 dBFS
THD = 74 dBc
SFDR Non HD2,HD3
= 97
−40
−60
Amplitude (dBFS)
Amplitude (dBFS)
125
G002
fIN = 10 MHz
SFDR = 84 dBc
SNR = 75.7 dBFS
SINAD = 75.2 dBFS
THD = 83 dBc
SFDR Non HD2, HD3
= 104 dBc
−20
−80
−100
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
25
G003
Figure 3. FFT for 300-MHz Input Signal
50
75
Frequency (MHz)
100
125
G004
Figure 4. FFT for 10-MHz Input Signal
(2.5-VPP Full-Scale)
0
0
fIN = 170 MHz
SFDR = 87 dBc
SNR = 74.7 dBFS
SINAD = 74.3 dBFS
THD = 84 dBc
SFDR Non HD2, HD3
= 93 dBc
−40
−60
fIN = 300 MHz
SFDR = 72 dBc
SNR = 73.3 dBFS
SINAD = 70 dBFS
THD = 72 dBc
SFDR Non HD2, HD3
= 93 dBc
−20
Amplitude (dBFS)
−20
Amplitude (dBFS)
100
0
−20
−80
−100
−120
50
75
Frequency (MHz)
Figure 2. FFT for 170-MHz Input Signal
0
−120
25
G001
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
Figure 5. FFT for 170-MHz Input Signal
(2.5-VPP Full-Scale)
125
−120
0
25
G005
50
75
Frequency (MHz)
100
125
G006
Figure 6. FFT for 300-MHz Input Signal
(2.5-VPP Full-Scale)
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Typical Characteristics: ADS42LB69 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, QDR interface, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point
FFT, unless otherwise noted.
0
0
Each Tone at
−7 dBFS Amplitude
fIN1 = 46 MHz
fIN2 = 50 MHz
2−Tone IMD = 97 dBFS
SFDR = 101 dBFS
−40
−60
−80
−100
−120
Each Tone at
−36 dBFS Amplitude
fIN1 = 46 MHz
fIN2 = 50 MHz
2−Tone IMD = 101 dBFS
SFDR = 103 dBFS
−20
Amplitude (dBFS)
Amplitude (dBFS)
−20
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
Figure 7. FFT for Two-Tone Input Signal
(At –7 dBFS, 46 MHz and 50 MHz)
−40
Amplitude (dBFS)
Amplitude (dBFS)
125
G008
Each Tone at
−36 dBFS Amplitude
fIN1 = 185 MHz
fIN2 = 190 MHz
2−Tone IMD = 107 dBFS
SFDR = 108 dBFS
−20
−60
−80
−100
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
100
125
G010
−92
fIN1 = 46 MHz
fIN2 = 50 MHz
Two − Tone IMD (dBFS)
−94
−98
−100
−102
−104
−106
−108
−36
50
75
Frequency (MHz)
Figure 10. FFT for Two-Tone Input Signal
(At –36 dBFS, 185 MHz and 190 MHz)
−94
−96
25
G009
Figure 9. FFT for Two-Tone Input Signal
(At –7 dBFS, 185 MHz and 190 MHz)
Two − Tone IMD (dBFS)
100
0
Each Tone at
−7 dBFS Amplitude
fIN1 = 185 MHz
fIN2 = 190 MHz
2−Tone IMD = 94 dBFS
SFDR = 96 dBFS
−20
fIN1 = 185 MHz
fIN2 = 190 MHz
−96
−98
−100
−102
−104
−106
−33
−30
−27 −24 −21 −18 −15
Each Tone Amplitude (dBFS)
−12
Figure 11. IMD3 vs Input Amplitude
(46 MHz and 50 MHz)
18
50
75
Frequency (MHz)
Figure 8. FFT for Two-Tone Input Signal
(At –36 dBFS, 46 MHz and 50 MHz)
0
−120
25
G007
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−9 −7
−108
−36
−33
−30
G011
−27 −24 −21 −18 −15
Each Tone Amplitude (dBFS)
−12
−9 −7
G012
Figure 12. IMD3 vs Input Amplitude
(185 MHz and 190 MHz)
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Typical Characteristics: ADS42LB69 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, QDR interface, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point
FFT, unless otherwise noted.
100
77
2−VPP Full−Scale
2.5−VPP Full−Scale
95
2−VPP Full−Scale
2.5−VPP Full−Scale
76
75
85
SNR (dBFS)
SFDR (dBc)
90
80
75
70
74
73
72
65
71
60
0
50
100
150
200
250
300
Input Frequency (MHz)
350
70
400
0
50
70
65
60
10 MHz
70 MHz
100 MHz
130 MHz
170 MHz
230 MHz
270 MHz
350 MHz
400 MHz
491 MHz
10 MHz
70 MHz
100 MHz
130 MHz
78
76
G014
170 MHz
230 MHz
270 MHz
350 MHz
400 MHz
491 Mhz
72
70
68
66
−2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Digital Gain (dB)
G015
−2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Gain (dB)
G016
Figure 16. SNR vs Digital Gain
75.5
77.5
120
77
110
76.5
100
76
75
90
74.5
80
74
70
73.5
60
73
50
72.5
72
−60
−50
−40
−30
−20
Amplitude (dBFS)
−10
0
130
Input Frequency = 170 MHz
SNR(dBFS)
SFDR(dBc)
SFDR(dBFS)
120
110
100
75.5
90
75
80
74.5
70
74
60
73.5
50
40
73
40
30
72.5
30
20
Figure 17. Performance Across Input Amplitude
(70 MHz)
SNR (dBFS)
SNR(dBFS)
SFDR(dBc)
SFDR(dBFS)
130
SFDR (dBc,dBFS)
Input Frequency = 70 MHz
76
SNR (dBFS)
400
74
Figure 15. SFDR vs Digital Gain
71.5
−70
350
Figure 14. SNR vs Input Frequency
77
76.5
150
200
250
300
Input Frequency (MHz)
80
SNR (dB)
SFDR (dBc)
Figure 13. SFDR vs Input Frequency
120
115
110
105
100
95
90
85
80
75
100
G013
72
−70
−60
−50
G017
−40
−30
−20
Amplitude (dBFS)
−10
0
SFDR (dBc,dBFS)
55
20
G018
Figure 18. Performance Across Input Amplitude
(170 MHz)
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Typical Characteristics: ADS42LB69 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, QDR interface, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point
FFT, unless otherwise noted.
SFDR (dBc)
94
Input Frequency = 170 MHz
75.5
92
75
90
74.5
88
74
86
73.5
84
73
82
1.85
75
92
74.5
89
74
86
73.5
83
73
80
1.85
G019
Figure 19. Performance vs Input Common-Mode Voltage
(70 MHz)
72.5
1.95
1.87
1.9
1.93
Input Common−Mode Voltage (V)
G020
Figure 20. Performance vs Input Common-Mode Voltage
(170 MHz)
93
75
AVDD = 1.7 V
AVDD = 1.75 V
AVDD = 1.8 V
92
91
AVDD = 1.85 V
AVDD = 1.9 V
AVDD = 1.7 V
AVDD = 1.75V
AVDD = 1.8 V
74.5
90
SNR (dBFS)
SFDR (dBc)
SFDR
SNR
95
72.5
1.95
1.87
1.9
1.93
Input Common−Mode Voltage (V)
75.5
98
SFDR (dBc)
SFDR
SNR
SNR (dBFS)
Input Frequency = 70 MHz
SNR (dBFS)
76
96
89
88
87
AVDD = 1.85 V
AVDD = 1.9 V
74
73.5
73
86
72.5
85
84
−40
Input Frequency = 170 MHz
−15
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
72
−40
85
Figure 21. SFDR vs AVDD Supply and Temperature
(170 MHz)
10
35
Temperature (°C)
60
85
G022
Figure 22. SNR vs AVDD Supply and Temperature
(170 MHz)
94
75
AVDD3V = 3.15 V
AVDD3V = 3.2 V
AVDD3V = 3.25 V
AVDD3V = 3.3 V
93
92
91
AVDD3V = 3.35 V
AVDD3V = 3.4 V
AVDD3V = 3.45 V
AVDD3V = 3.15 V
AVDD3V = 3.2 V
AVDD3V = 3.25 V
AVDD3V = 3.3 V
74.5
90
SNR (dBFS)
SNR (dBFS)
−15
G021
89
88
87
AVDD3V = 3.35 V
AVDD3V = 3.4 V
AVDD3V = 3.45 V
74
73.5
73
86
85
84
83
−40
72.5
Input Frequency = 170 MHz
−15
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
85
Submit Documentation Feedback
−15
G023
Figure 23. SFDR vs AVDD_BUF Supply and Temperature
(170 MHz)
20
72
−40
10
35
Temperature (°C)
60
85
G024
Figure 24. SNR vs AVDD_BUF Supply and Temperature
(170 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
ADS42LB49, ADS42LB69
www.ti.com
SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Typical Characteristics: ADS42LB69 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, QDR interface, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point
FFT, unless otherwise noted.
92
76
DRVDD = 1.7 V
DRVDD = 1.75 V
DRVDD = 1.8 V
91
DRVDD = 1.7 V
DRVDD = 1.75 V
DRVDD = 1.8 V
75
SNR (dBFS)
SFDR (dBc)
90
DRVDD = 1.85 V
DRVDD = 1.9 V
89
88
87
86
DRVDD = 1.85 V
DRVDD = 1.9 V
74
73
72
85
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
85
Figure 25. SFDR vs DRVDD Supply and Temperature
(170 MHz)
76
92
75
90
74
88
73
86
72
84
0.1
0.3
0.5 0.7 0.9 1.1 1.3 1.5 1.7
Differential Clock Amplitudes (Vpp)
1.9
71
2.1
90
74
88
72
86
70
84
0.1
77
76
90
75
88
74
86
73
84
30
40
50
60
Input Clock Duty Cycle (%)
70
1.9
68
2.1
G028
77
Input Frequency = 170 MHz
92
82
0.5 0.7 0.9 1.1 1.3 1.5 1.7
Differential Clock Amplitudes (Vpp)
94
92
SNR
SFDR
76
90
75
88
74
86
73
72
84
72
71
82
Figure 29. Performance vs Clock Duty Cycle
(70 MHz)
SFDR (dBc)
SNR (dBFS)
SFDR (dBc)
94
0.3
Figure 28. Performance vs Clock Amplitude
(170 MHz)
78
SNR
SFDR
SFDR
SNR
76
Figure 27. Performance vs Clock Amplitude
(70 MHz)
Input Frequency = 70 MHz
G026
92
G027
96
85
78
Input Frequency =170 MHz
SFDR (dBc)
SFDR (dBc)
94
60
94
SNR (dBFS)
SFDR
SNR
10
35
Temperature (°C)
Figure 26. SNR vs DRVDD Supply and Temperature
(170 MHz)
77
96
Input Frequency = 70 MHz
−15
G025
SNR (dBFS)
−15
Input Frequency = 170 MHz
71
−40
G029
30
40
50
60
Input Clock Duty Cycle (%)
70
SNR (dBFS)
84
−40
71
G030
Figure 30. Performance vs Clock Duty Cycle
(170 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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ADS42LB49, ADS42LB69
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6.13 Typical Characteristics: ADS42LB49
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
0
0
fIN = 10 MHz
SFDR = 88 dBc
SNR = 73.3 dBFS
SINAD = 73.2 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 102 dBc
−40
−60
−20
Amplitude (dBFS)
Amplitude (dBFS)
−20
−80
−100
−120
fIN = 170 MHz
SFDR = 89 dBc
SNR = 72.75 dBFS
SINAD = 72.6 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 101 dBc
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
Figure 31. FFT for 10-MHz Input Signal
fIN = 300 MHz
SFDR = 76 dBc
SNR = 71.75 dBFS
SINAD = 70.3 dBFS
THD = 74 dBc
SFDR Non HD2, HD3
= 96 dBc
−60
Amplitude (dBFS)
Amplitude (dBFS)
−40
−80
−40
−60
G032
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
25
G033
Figure 33. FFT for 300-MHz Input Signal
50
75
Frequency (MHz)
100
125
G034
Figure 34. FFT for 10-MHz Input Signal
(2.5-VPP Full-Scale)
0
0
fIN = 170 MHz
SFDR = 87 dBc
SNR = 74 dBFS
SINAD = 73.6 dBFS
THD = 83 dBc
SFDR Non HD2, HD3
= 92 dBc
−40
−60
fIN = 300 MHz
SFDR = 72 dBc
SNR = 72.8 dBFS
SINAD = 69.5 dBFS
THD = 71 dBc
SFDR Non HD2, HD3
= 95 dBc
−20
Amplitude (dBFS)
−20
Amplitude (dBFS)
125
fIN = 10 MHz
SFDR = 85 dBc
SNR = 74.8 dBFS
SINAD = 74.4 dBFS
THD = 84 dBc
SFDR Non HD2, HD3
= 103 dBc
−20
−100
−80
−100
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
Figure 35. FFT for 170-MHz Input Signal
(2.5-VPP Full-Scale)
22
100
0
−20
−120
50
75
Frequency (MHz)
Figure 32. FFT for 170-MHz Input Signal
0
−120
25
G031
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125
−120
0
25
G035
50
75
Frequency (MHz)
100
125
G036
Figure 36. FFT for 300-MHz Input Signal
(2.5-VPP Full-Scale)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
ADS42LB49, ADS42LB69
www.ti.com
SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Typical Characteristics: ADS42LB49 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
0
0
Each Tone at
−7 dBFS Amplitude
fIN1 = 46 MHz
fIN2 = 50 MHz
2−Tone IMD = 99 dBFS
SFDR = 103 dBFS
−40
−60
−80
−100
−120
Each Tone at
−36 dBFS Amplitude
fIN1 = 46 MHz
fIN2 = 50 MHz
2−Tone IMD = 100 dBFS
SFDR = 103 dBFS
−20
Amplitude (dBFS)
Amplitude (dBFS)
−20
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
Figure 37. FFT for Two-Tone Input Signal
(At –7 dBFS, 46 MHz and 50 MHz)
125
G038
−40
Each Tone at
−36 dBFS Amplitude
fIN1 = 185 MHz
fIN2 = 190 MHz
2−Tone IMD = 106dBFS
SFDR = 108 dBFS
−20
Amplitude (dBFS)
Amplitude (dBFS)
100
0
Each Tone at
−7 dBFS Amplitude
fIN1 = 185 MHz
fIN2 = 190 MHz
2−Tone IMD = 93 dBFS
SFDR = 97 dBFS
−20
−60
−80
−100
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
−120
125
0
100
125
G040
−92
fIN1 = 46 MHz
fIN2 = 50 MHz
Two − Tone IMD (dBFS)
−94
−98
−100
−102
−104
−106
−108
−36
50
75
Frequency (MHz)
Figure 40. FFT for Two-Tone Input Signal
(At –36 dBFS, 185 MHz and 190 MHz)
−94
−96
25
G039
Figure 39. FFT for Two-Tone Input Signal
(At –7 dBFS, 185 MHz and 190 MHz)
Two − Tone IMD (dBFS)
50
75
Frequency (MHz)
Figure 38. FFT for Two-Tone Input Signal
(At –36 dBFS, 46 MHz and 50 MHz)
0
−120
25
G037
fIN1 = 185 MHz
fIN2 = 190 MHz
−96
−98
−100
−102
−104
−106
−33
−30
−27 −24 −21 −18 −15
Each Tone Amplitude (dBFS)
−12
Figure 41. IMD3 vs Input Amplitude
(46 MHz and 50 MHz)
−9 −7
−108
−36
−33
−30
G041
−27 −24 −21 −18 −15
Each Tone Amplitude (dBFS)
−12
−9 −7
G042
Figure 42. IMD3 vs Input Amplitude
(185 MHz and 190 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
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Typical Characteristics: ADS42LB49 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
100
77
2−VPP Full−Scale
2.5−VPP Full−Scale
95
2−VPP Full−Scale
2.5−VPP Full−Scale
76
90
75
SNR (dBFS)
SFDR (dBc)
85
80
75
70
74
73
72
65
71
60
0
50
100
150
200
250
300
Input Frequency (MHz)
350
70
400
0
50
Figure 43. SFDR vs Input Frequency
10 MHz
70 MHz
130 MHz
350 MHz
400 MHz
491 MHz
10 MHz
70 MHz
100 MHz
130 MHz
76
SNR (dBFS)
SFDR (dBc)
170 MHz
230 MHz
270 MHz
90
80
70
170 MHz
230 MHz
270 MHz
350 MHz
400 MHz
491 MHz
72
70
66
−2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Gain (dB)
G045
−2 −1.5 −1 −0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Digital Gain (dB)
G046
Figure 46. SNR vs Digital Gain
75.5
77
120
76.5
110
76
100
75.5
75
90
74.5
80
74
70
73.5
60
73
50
72.5
72
−60
−50
−40
−30
−20
Amplitude (dBFS)
−10
0
SNR(dBFS)
SFDR(dBc)
SFDR(dBFS)
120
110
100
90
74.5
80
74
70
73.5
60
73
50
40
72.5
40
30
72
30
20
Figure 47. Performance Across Input Amplitude
(70 MHz)
Submit Documentation Feedback
130
Input Frequency = 170 MHz
75
SNR (dBFS)
SNR(dBFS)
SFDR(dBc)
SFDR(dBFS)
130
SFDR (dBc,dBFS)
Input Frequency = 70 MHz
76
SNR (dBFS)
G044
74
Figure 45. SFDR vs Digital Gain
24
400
68
77
71.5
−70
350
78
100
76.5
150
200
250
300
Input Frequency (MHz)
Figure 44. SNR vs Input Frequency
110
60
100
G043
71.5
−70
−60
−50
G047
−40
−30
−20
Amplitude (dBFS)
−10
0
SFDR (dBc,dBFS)
55
20
G048
Figure 48. Performance Across Input Amplitude
(170 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
ADS42LB49, ADS42LB69
www.ti.com
SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Typical Characteristics: ADS42LB49 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
SFDR (dBc)
96
Input Frequency = 170 MHz
75.5
94
75
92
74.5
89
74
86
73.5
84
73
82
1.85
74.5
92
74
89
73.5
86
73
83
72.5
80
1.85
G049
Figure 49. Performance vs Input Common-Mode Voltage
(70 MHz)
72
1.95
1.875
1.9
1.925
Input Common−Mode Voltage (V)
G050
Figure 50. Performance vs Input Common-Mode Voltage
(170 MHz)
93
75
AVDD = 1.7 V
AVDD = 1.75 V
AVDD = 1.8 V
92
91
AVDD = 1.85 V
AVDD = 1.9 V
AVDD = 1.7 V
AVDD = 1.75V
AVDD = 1.8 V
74.5
AVDD = 1.85 V
AVDD = 1.9 V
74
90
SNR (dBFS)
SFDR (dBc)
SFDR
SNR
95
72.5
1.95
1.875
1.9
1.925
Input Common−Mode Voltage (V)
75
98
SFDR (dBc)
SFDR
SNR
SNR (dBFS)
Input Frequency = 70 MHz
SNR (dBFS)
76
99
89
88
87
73.5
73
72.5
86
85
84
−40
72
Input Frequency = 170 MHz
−15
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
71.5
−40
85
Figure 51. SFDR vs AVDD Supply and Temperature
(170 MHz)
10
35
Temperature (°C)
60
85
G052
Figure 52. SNR vs AVDD Supply and Temperature
(170 MHz)
94
74.5
AVDD3V = 3.15 V
AVDD3V = 3.2 V
AVDD3V = 3.25 V
AVDD3V = 3.3 V
93
92
91
AVDD3V = 3.35 V
AVDD3V = 3.4 V
AVDD3V = 3.45 V
AVDD3V = 3.15 V
AVDD3V = 3.2 V
AVDD3V = 3.25 V
AVDD3V = 3.3 V
74
90
SNR (dBFS)
SFDR (dBc)
−15
G051
89
88
87
AVDD3V = 3.35 V
AVDD3V = 3.4 V
AVDD3V = 3.45 V
73.5
73
72.5
86
85
84
83
−40
72
Input Frequency = 170 MHz
−15
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
85
71.5
−40
−15
G053
Figure 53. SFDR vs AVDD_BUF Supply and Temperature
(170 MHz)
10
35
Temperature (°C)
60
85
G054
Figure 54. SNR vs AVDD_BUF Supply and Temperature
(170 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
www.ti.com
Typical Characteristics: ADS42LB49 (continued)
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
92
75
DRVDD = 1.7 V
DRVDD = 1.75 V
DRVDD = 1.8 V
91
DRVDD = 1.7 V
DRVDD = 1.75 V
DRVDD = 1.8 V
74.5
89
88
87
73.5
73
72.5
86
72
85
Input Frequency = 170 MHz
10
35
Temperature (°C)
60
85
Figure 55. SFDR vs DRVDD Supply and Temperature
(170 MHz)
76
92
75
90
74
88
73
86
72
0.3
0.5 0.7 0.9 1.1 1.3 1.5 1.7
Differential Clock Amplitudes (Vpp)
1.9
71
2.1
90
74
88
72
86
70
84
0.1
1.9
68
2.1
G058
77
96
Input Frequency = 170 MHz
SNR
SFDR
94
92
76
92
75
90
75
90
74
88
74
88
73
86
73
86
72
84
72
84
71
71
82
82
30
40
50
60
Input Clock Duty Cycle (%)
70
Figure 59. Performance vs Clock Duty Cycle
(70 MHz)
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SFDR (dBc)
SNR (dBFS)
SFDR (dBc)
0.5 0.7 0.9 1.1 1.3 1.5 1.7
Differential Clock Amplitudes (Vpp)
77
94
26
0.3
Figure 58. Performance vs Clock Amplitude
(170 MHz)
78
SNR
SFDR
SFDR
SNR
76
Figure 57. Performance vs Clock Amplitude
(70 MHz)
Input Frequency = 70 MHz
G056
92
G057
96
85
78
Input Frequency = 170 MHz
SFDR (dBc)
SFDR (dBc)
94
60
94
SNR (dBFS)
SFDR
SNR
10
35
Temperature (°C)
Figure 56. SNR vs DRVDD Supply and Temperature
(170 MHz)
77
96
Input Frequency = 70 MHz
−15
G055
SNR (dBFS)
−15
Input Frequency = 170 MHz
71.5
−40
G059
30
40
50
60
Input Clock Duty Cycle (%)
70
76
SNR (dBFS)
84
−40
84
0.1
DRVDD = 1.85 V
DRVDD = 1.9 V
74
SNR (dBFS)
SFDR (dBc)
90
DRVDD = 1.85 V
DRVDD = 1.9 V
70
G060
Figure 60. Performance vs Clock Duty Cycle
(170 MHz)
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
6.14 Typical Characteristics: Common
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 32k-point FFT, unless
otherwise noted.
0
Amplitude (dBFS)
−20
−40
−60
CMRR (dB)
fIN = 100 MHz
SFDR = 82 dBc
fCM = 5 MHz
50 − mVPP
Amplitude(fIN) = −1 dBFS
Amplitude(fCM) = −105 dBFS
Amplitude(fIN + fCM) = −90 dBFS
Amplitude(fIN − fCM) = −86 dBFS
−80
−100
−120
0
25
50
75
Frequency (MHz)
100
125
0
−5
−10
−15
−20
−25
−30
−35
−40
−45
−50
−55
−60
−65
Input Frequency = 10MHz
50−mVPP Signal Superimposed on VCM
0
G061
Figure 61. CMRR FFT
300
G062
Figure 62. CMRR vs Test Signal Frequency
0
−20
fIN = 20 MHz
SFDR = 89 dBc
fPSRR = 4 MHz
50 − mVPP
Amplitude(fIN) = −1 dBFS
Amplitude(fPSRR) = −104.5 dBFS
Amplitude(fIN + fPSRR) = −92.8 dBFS
Amplitude(fIN − fPSRR) = −94.5 dBFS
−40
−60
50−mVPP Signal Superimposed on AVDD
100−mVPP Signal Superimposed on AVDD3V
−30
−40
PSRR (dB)
−20
Amplitude (dBFS)
50
100
150
200
250
Common−Mode Test Signal Frequency (MHz)
−80
−50
−60
−70
−100
−80
−120
−90
Input Frequency = 20MHz
0
25
50
75
Frequency (MHz)
100
125
0
50
100
150
200
250
Test Signal Frequency on Supply (MHz)
G063
Figure 63. PSRR FFT for AVDD Supply
300
G064
Figure 64. PSRR vs Test Signal Frequency
2
AVDD Power
DVDD Power
AVDD3V Power
Total Power
1.8
Total Power (W)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0
50
100
150
Sampling Speed (MSPS)
200
250
G065
Figure 65. Total Power vs Sampling Frequency
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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www.ti.com
6.15 Typical Characteristics: Contour
Typical values are at TA = +25°C, full temperature range is TMIN = –40°C to TMAX = +85°C, ADC sampling rate = 250 MSPS,
50% clock duty cycle, AVDD3V = 3.3 V, AVDD = DRVDD = 1.8 V, –1-dBFS differential input, and 65k-point FFT, unless
otherwise noted.
6.15.1 Spurious-Free Dynamic Range (SFDR): General
Sampling Frequency, MSPS
240
91
91
220
75
79
87 83
71
67
91
200
180
91
91
160
83
87
75
79
71
67
140
120
87
87
100
91
83
87
80
50
100
65
150
200
250
Input Frequency, MHz
70
75
79
71
75
300
80
67
350
85
400
90
Figure 66. SFDR (0-dB Gain)
240
Sampling Frequency, MSPS
85
220
80
75
70
90
200
180
160
90
95
85
80
75
70
140
120
95
95
100
90
80
100
70
200
75
85
80
75
300
400
Input Frequency, MHz
80
85
70
500
600
90
95
Figure 67. SFDR (6-dB Gain)
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6.15.2 Signal-to-Noise Ratio (SNR): ADS42LB69
240
Sampling Frequency, MSPS
73.5
72.5
73
220
72
71.5
71
200
180
73.5
160
72.5
73
72
71.5
71
140
120
100
73.5
74
80
69.5
50
100
70
70.5
72.5 72 71.5
73
150
200
250
Input Frequency, MHz
71
71.5
72
70.5
71
70
300
72.5
350
73
400
73.5
74
Figure 68. SNR (0-dB Gain, 16 Bits)
Sampling Frequency, MSPS
240
220
67.75
68
67.5
67
66.5
200
180
160
67.75
68
67.5
67
66.5
140
120
100
68
80
65
100
65.5
67.75 67.5
200
66
67
66.5
66
300
400
Input Frequency, MHz
66.5
67
65.5
500
600
67.5
68
Figure 69. SNR (6-dB Gain, 16 Bits)
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6.15.3 Signal-to-Noise Ratio (SNR): ADS42LB49
Sampling Frequency, MSPS
240
73
220
71.5
72
72.5
71
200
180
160
72.5
73
72
71.5
71
70.5
140
120
100
73.5
80
50
69.5
72.5
73
100
70
72 71.5 71
150
200
250
Input Frequency, MHz
70.5
71
71.5
72
70.5
70
300
350
400
73
73.5
72.5
Figure 70. SNR (0-dB Gain, 14 Bits)
240
67.75
67.25
67.5
67
Sampling Frequency, MSPS
220
66.5
66
200
180
160
67.75
67.5
67.25
67
66.5
140
66
120
100
67.5 67.25
67.75
80
50
65
100
65.5
150
200
66.5
67
250
300
350
Input Frequency, MHz
66
66.5
400
66
450
67
65.5
500
550
600
67.5
Figure 71. SNR (6-dB Gain, 14 Bits)
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7 Parameter Measurement Information
Sample N
tSU_SYNCIN
tH_SYNCIN
CLKIN
SYNCIN
Figure 72. Timing Diagram for SYNCINP and SYNCINM Inputs
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tA
INxP
Sample N
tPD
Data Latency: 14 Clock Cycles
CLKINP
CLKINM
CLKOUTP
CLKOUT edges are centered
within the data valid window
CLKOUTM
Dx[15:0]
E
O
E
E
O
E
O
E
tSU
O
E
O
E
N-1
tH
O
N
CLKOUTM
CLKOUTP
Dx0P, Dx0M
D0
D1
D0
D1
Dx2P, Dx2M
D2
D3
D2
D3
Dx4P, Dx4M
D4
D5
D4
D5
Dx6P, Dx6M
D6
D7
D6
D7
Dx8P, Dx8M
D8
D9
D8
D9
Dx10P, Dx10M
D10
D11
D10
D11
Dx12P, Dx12M
D12
D13
D12
D13
Dx14P, Dx14M
(16-Bit Version Only)
D14
D15
D14
D15
Sample N
Sample N+1
Figure 73. DDR LVDS Output Timing Diagram
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tA
INxP
Sample N
TPD
Data Latency: 14 Clock Cycles
CLKINP
CLKINM
DxCLKP
DxCLK edges are centered
in the data valid window.
DxCLKM
DxFRAMEM
DxFRAMEP
N-1
CLKIN, DxCLK, DxFRAMEP (x = A or B) are differential:
KvoÇ šZ ZW[ ‰}•]š]À •]Pv o •Z}Áv (}Œ o Œ]šÇ.
N
N+1
DA0M, DB0M
12
8
4
0
12
8
4
0
12
13
9
5
1
13
9
5
1
13
14
10
6
2
14
10
6
2
14
15
11
7
3
15
11
7
3
15
DA0P, DB0P
DA1M, DB1M
DA1P, DB1P
DA2M, DB2M
DA2P, DB2P
DA3M, DB3M
DA3P, DB3P
tsu
th
Figure 74. QDR LVDS Output Timing Diagram
DAn_P
DBn_P
Logic 0
VODL = -350 mV
Logic 1
(1)
VODH = +350 mV
(1)
DAn_M
DBn_M
VOCM
GND
(1) With an external 100-Ω termination.
Figure 75. DDR LVDS Output Voltage Levels
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8 Detailed Description
8.1 Overview
The ADS42LB69 and ADS42LB49 is a family of high linearity, buffered analog input, dual-channel ADCs with
maximum sampling rates up to 250 MSPS employing either a quadruple data rate (QDR) or double data rate
(DDR) LVDS interface. 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 14 clock cycles. The output is available in LVDS logic levels in
SPI-programmable QDR or DDR options.
8.2 Functional Block Diagrams
ADS42LB69
16-Bit
ADC
INAP,
INAM
Digital Gain
and Test
Patterns
CLKOUTP,
CLKOUTM
DDR LVDS
Delay
Digital
Block
16-Bit
ADC
INBP,
INBM
Common
Mode
Output
Formatter
Digital Gain
and Test
Patterns
DB[15:0]P,
DB[15:0]M
DDR LVDS
CTRL2
CTRL1
SDOUT
SEN
SCLK
SDATA
Configuration
Registers
RESET
VCM
DA[15:0]P,
DA[15:0]M
Output
Formatter
Divide
by 1,2,4
CLKINP,
CLKINM
SYNCINP,
SYNCINM
Digital
Block
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Figure 76. ADS42LB69 DDR LVDS
ADS42LB49
14-Bit
ADC
INAP,
INAM
Digital Gain
and Test
Patterns
CLKOUTP,
CLKOUTM
DDR LVDS
Delay
Digital
Block
14-Bit
ADC
DB[13:0]P,
DB[13:0]M
DDR LVDS
CTRL2
CTRL1
Configuration
Registers
RESET
SEN
SCLK
Common
Mode
Output
Formatter
Digital Gain
and Test
Patterns
SDATA
SDOUT
INBP,
INBM
VCM
DA[13:0]P,
DA[13:0]M
Output
Formatter
Divide
by 1,2,4
CLKINP,
CLKINM
SYNCINP,
SYNCINM
Digital
Block
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Figure 77. ADS42LB49 DDR LVDS
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Functional Block Diagrams (continued)
ADS42LB49, ADS42LB69
OVRA
Digital
Block
14-, 16-Bit
ADC
INAP,
INAM
CLKINP,
CLKINM
Output
Formatter
Digital Gain
and Test
Patterns
DAFRAMEP,
AFRAMEM
DACLKP,
DACLKM
QDR
LVDS
DA[3:0]P,
DA[3:0]M
Divide
by 1,2,4
SYNCINP,
SYNCINM
Delay
14-, 16-Bit
ADC
INBP,
INBM
DB[3:0]P,
B[3:0]MM
Digital
Block
Output
Formatter
Digital Gain
and Test
Patterns
DBCLKP,
BCLKM
DBFRAMEP,
BFRAMEM
QDR
LVDS
OVRB
Common
Mode
CTRL1
CTRL2
SDATA
SDOUT
SEN
SCLK
Configuration
Registers
RESET
VCM
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Figure 78. ADS42LB69, ADS42LB49 QDR LVDS
8.3 Feature Description
8.3.1 Digital Gain
The device includes gain settings that can be used to obtain improved SFDR performance (compared to no
gain). Gain is programmable from –2 dB to 6 dB (in 0.5-dB steps). For each gain setting, the analog input fullscale range scales proportionally. Table 3 shows how full-scale input voltage changes when digital gain are
programmed in 1-dB steps. Refer to Table 16 to set digital gain using a serial interface register.
SFDR improvement is achieved at the expense of SNR; for a 1-dB increase in digital gain, SNR degrades
approximately between 0.5 dB and 1 dB (refer to Figure 15 and Figure 16). Therefore, gain can be used as a
trade-off between SFDR and SNR. Note that the default gain after reset is 0 dB with a 2.0-VPP full-scale voltage.
Table 3. Full-Scale Range Across Gains
(1)
DIGITAL GAIN
FULL-SCALE INPUT VOLTAGE
–2 dB
2.5 VPP (1)
–1 dB
2.2 VPP
0 dB (default)
2.0 VPP
1 dB
1.8 VPP
2 dB
1.6 VPP
3 dB
1.4 VPP
4 dB
1.25 VPP
5 dB
1.1 VPP
6 dB
1.0 VPP
Shaded cells indicate performance settings used in the Electrical
Characteristics and Typical Characteristics.
8.3.2 Input Clock Divider
The device is equipped with an internal divider on the clock input. This divider allows operation with a faster input
clock, simplifying the system clock distribution design. The clock divider can be bypassed (divide-by-1) for
operation with a 250-MHz clock. The divide-by-2 option supports a maximum 500-MHz input clock and the
divide-by-4 option supports a maximum 1-GHz input clock frequency.
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8.3.3 Overrange Indication
The device provides two different overrange indications: normal OVR and fast OVR. Normal OVR (default) is
triggered if the final 16-bit data output exceeds the maximum code value. Normal OVR latency is the same as
the output data (that is, 14 clock cycles). Fast OVR is triggered if the input voltage exceeds the programmable
overrange threshold and is presented after a latency of only nine clock cycles, thus enabling a quicker reaction to
an overrange event.
8.3.3.1 OVR in a QDR Pinout
In a QDR interface, the overrange indication is output on the OVRA and OVRB pins (pin 54 and 59) in 1.8-V
CMOS logic levels. The same overrange indication can also be made available on the bidirectional CTRL1,
CTRL2 pins by using the PDN/OVR FOR CTRL PINS register bit, as described in Figure 79. Using the FAST
OVR EN register bit, the fast OVR indication can be presented on these pins instead of normal OVR.
Pin 59
(OVRB)
Pin 54
(OVRA)
QDR Pinout
(Default)
Pin 12
(CTRL2)
Pin 37
(CTRL1)
NOTE: By default, normal OVR is output on the OVRA and OVRB pins. Using the FAST OVR EN register bit, fast OVR can be presented on
these pins instead.
NOTE: When the PDN/OVR FOR CTRL PINS register bit is set, the CTRL1 and CTRL2 pins function as output pins and carry the same
information as the OVRA and OVRB pins (respectively) in 1.8-V CMOS logic levels.
Figure 79. OVR in a QDR Pinout
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8.3.3.2 OVR in a DDR Pinout
In the DDR interface, there are no dedicated pins to provide overrange indication. However, by choosing the
appropriate register bits, OVR can be transferred on the LSB of 16-bit output data as well as on the bidirectional
CTRL1 and CTRL2 pins, as shown in Figure 80.
Use the OVR ON LSB register bits to transfer channel A and channel B OVR information.
Channel A OVR information is transferred on pins 39 and 40 in LVDS logic levels. Channel B OVR information is transferred on pins 9 and 10.
Note that these pins are Dx0P, Dx0M in the ADS42LB69 and are NC in the ADS42LB49.
Pin 9 (DB0M)
Pin 40 (DA0P)
Pin 10 (DB0P)
Pin 39 (DA0M)
DDR Pinout
(Set the DDR-QDR register bit.)
Pin 12 (CTRL2)
Pin 37 (CTRL1)
By default, the DDR pinout does not provide OVR information. Use the PDN/OVR FOR CTRL PINS register bit to transfer OVR information.
Channel A OVR information is transferred on the CTRL1 pin and channel B OVR information is transferred on the CTRL2 pin in 1.8-V CMOS logic levels.
Figure 80. OVR in a DDR Pinout
The FAST OVR EN register bit can be used to transfer fast OVR indication on the CTRL1 and CTRL2 pins
instead of normal OVR. The OVR ON LSB register bits can be used to transfer fast OVR indication on the LSB
bits (Dx0P, Dx0M), as described in Table 4.
Table 4. Fast OVR Transfer
OVR ON LSB BIT SETTINGS
PIN STATE FOR PINS 9, 10 AND 39, 40
00
D0 and D1 are output in the ADS42LB69, NC for the ADS42LB49
01
Fast OVR in LVDS logic level
10
Normal OVR in LVDS logic level
11
D0 and D1 are output in the ADS42LB69, NC for the ADS42LB49
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Table 5 summarizes the availability of OVR information on different pins in the QDR and DDR interfaces and the
required register settings.
Table 5. OVR Information Availability
OVR INFORMATION AVAILABILITY
INTERFACE
QDR
DDR
8.3.3.3
SETTINGS
PINS 9, 10 AND 39, 40
(LVDS Logic Levels)
PINS 12 AND 37
(CMOS Logic Levels)
PINS 54 AND 59
(CMOS Logic Levels)
Default
Not applicable
No
Yes
Use the PDN/OVR FOR
CTRL PINS register bits
Not applicable
Yes
Yes
Default
No
No
Not applicable
Use the OVR ON LSB
register bits
Yes
No
Not applicable
Use the PDN/OVR FOR
CTRL PINS register bits
No
Yes
Not applicable
Use the OVR ON LSB and
PDN/OVR FOR CTRL PINS
register bits
Yes
Yes
Not applicable
Programming Threshold for Fast OVR
The input voltage level at which the overload is detected is referred to as the threshold and is programmable
using the FAST OVR THRESHOLD bits. Fast OVR is triggered nine output clock cycles after the overload
condition occurs. The threshold voltage amplitude at which fast OVR is triggered is Equation 1:
1 × [the decimal value of the FAST OVR THRESH bits] / 127
(1)
When digital gain is programmed (for gain values > 0 dB ), the threshold voltage amplitude is Equation 2:
10–Gain / 20 x [the decimal value of the FAST OVR THRESH bits] / 127
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8.3.4 LVDS Buffer
The equivalent circuit of each LVDS output buffer is shown in Figure 81. After reset, the buffer presents an
output impedance of 100 Ω to match with the external 100-Ω termination.
VDIFF
High
Low
OUTP
External
100-W Load
OUTM
VOCM
ROUT
VDIFF
Low
High
NOTE: Default swing across 100-Ω load is ±350 mV. Use the LVDS SWING bits to change the swing.
Figure 81. LVDS Buffer Equivalent Circuit
The VDIFF voltage is nominally 350 mV, resulting in an output swing of ±350 mV with 100-Ω external termination.
The VDIFF voltage is programmable using the LVDS SWING register bits from ±125 mV to ±570 mV.
Additionally, a mode exists to double the strength of the LVDS buffer to support 50-Ω differential termination, as
shown in Figure 82. This mode can be used when the output LVDS signal is routed to two separate receiver
chips, each using a 100-Ω termination. The mode can be enabled for LVDS output data (and for the frame clock
in the QDR interface) buffers by setting the LVDS DATA STRENGTH register bit. For LVDS output clock buffers
(applicable for both DDR and QDR interfaces), set both the LVDS CLKOUT STRENGTH EN and LVDS CLKOUT
STRENGTH register bits to '1'.
The buffer output impedance behaves in the same way as a source-side series termination. Absorbing reflections
from the receiver end helps improve signal integrity.
Receiver Chip 1
(for example, GC5330)
DAnP, DAnM
CLKIN1
100 W
CLKIN2
100 W
CLKOUTP
CLKOUTM
DBnP, DBnM
Receiver Chip 2
Device
LVDS CLKOUT STRENGTH EN and
LVDS CLKOUT STRENGTH = 1
Figure 82. LVDS Buffer Differential Termination
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8.3.5 Output Data Format
Two output data formats are supported: twos complement and offset binary. The format can be selected using
the DATA FORMAT serial interface register bit.
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 3FFFh for the ADS42LB49 and ADS42LB69 in offset binary output format; the
output code is 1FFFh for the ADS42LB49 and ADS42LB69 in twos complement output format. For a negative
input overdrive, the output code is 0000h in offset binary output format and 2000h for the ADS42LB49 and
ADS42LB69 in twos complement output format.
8.4 Device Functional Modes
8.4.1 Digital Output Information
The ADS42LB49 and ADS42LB69 provides 14- and 16-bit digital data for each channel and output clock
synchronized with the data.
8.4.1.1 Output Interface
Digital outputs are available in quadruple data rate (QDR) LVDS, and double data rate (DDR) LVDS formats,
selectable by the DDR – QDR serial register bit.
8.4.1.2 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, as shown in Figure 83.
Pins
CLKOUTP
CLKOUTM
LVDS Output Buffers
Dx0P
16-Bit ADC Data,
(1)
Channel X
Dx0M
Dx2P
Dx2M
Dx4P
Dx4M
Dx6P
Dx6M
Dx8P
Dx8M
Dx10P
Dx10M
Dx12P
Dx12M
Dx14P
Dx14M
Output
Clock
Data Bits
D0, D1
Data Bits
D2, D3
Data Bits
D4, D5
Data Bits
D6, D7
Data Bits
D8, D9
Data Bits
D10, D11
Data Bits
D12, D13
Data Bits
D14, D15
(1) X = A or B (for channel A or channel B).
Figure 83. DDR LVDS Interface
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Device Functional Modes (continued)
Even data bits (D0, D2, D4, and so forth) are output at the CLKOUTP rising edge and the odd data bits (D1, D3,
D5, and so forth) are output at the CLKOUTP falling edge. Both the CLKOUTP rising and falling edges must be
used to capture all the data bits, as shown in Figure 84.
CLKOUTM
CLKOUTP
DA0, DB0
D0
D1
D0
D1
DA2, DB2
D2
D3
D2
D3
DA4, DB4
D4
D5
D4
D5
DA6, DB6
D6
D7
D6
D7
DA8, DB8
D8
D9
D8
D9
DA10, DB10
D10
D11
D10
D11
DA12, DB12
D12
D13
D12
D13
DA14, DB15
(ADS42LB69 Only)
D14
D15
D14
D15
Sample N
Sample N + 1
Figure 84. DDR LVDS Interface Timing
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Device Functional Modes (continued)
8.4.1.3 QDR LVDS Outputs
The data bits and output clocks are output using low-voltage differential signal (LVDS) levels. Four data bits are
multiplexed and output on each LVDS differential data pair and are accompanied by a bit clock and a frame clock
for each channel, as shown in Figure 85.
QDR LVDS Data Buffers
Dx0P(1),
Dx0M
Dx1P,
Dx1M
Serializer
Dx2P,
Dx2M
16-Bit Data
Dx3P,
Dx3M
DxFRAMEP,
DxFRAMEM
Device
(1) X = channels A and B.
Figure 85. QDR LVDS Interface
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Device Functional Modes (continued)
Figure 86 shows the QDR interface bit order for the ADS42LB69 and Figure 87 shows the QDR interface bit
order for the ADS42LB49.
DACLKM, DBCLKM
DACLKM, DBCLKM
DACLKP, DBCLKP
DACLKP, DBCLKP
DAFRAMEM, DBFRAMEM
DAFRAMEM, DBFRAMEM
DAFRAMEP, DBFRAMEP
DAFRAMEP, DBFRAMEP
DA0, DB0
12
8
4
0
12
8
4
0
12
DA1, DB1
13
9
5
1
13
9
5
1
13
DA2, DB2
14
10
6
2
14
10
6
2
14
DA3, DB3
15
11
7
3
15
11
7
3
15
Sample N
DA0, DB0
10
6
2
Static
10
6
2
Static
10
DA1, DB1
11
7
3
Static
11
7
3
Static
11
DA2, DB2
12
8
4
0
12
8
4
0
12
DA3, DB3
13
9
5
1
13
9
5
1
13
Sample N
Sample N+1
Figure 86. QDR LVDS Interface Timing: ADS42LB69
Sample N+1
Figure 87. QDR LVDS Interface Timing: ADS42LB49
8.5 Programming
8.5.1 Device Configuration
The ADS42LB49 and ADS42LB69 can be configured using a serial programming interface, as described in this
section. In addition, the device has two bidirectional parallel pins (CTRL1 and CTRL2). By default, these pins act
as input pins and control the power-down modes, as described in Table 6 and Table 7. These pins can be
programmed as output pins that deliver overrange information by setting the PDN/OVR_FOR_CTRL_PINS
register bit.
Table 6. PDN/OVR_FOR_CTRL_PINS Bit (Set to '0')
CTRL2
CTRL1
PIN DIRECTION
FUNCTION
Low
Low
Input
Default operation
Low
High
Input
Channel A power-down
High
Low
Input
Channel B powers down in QDR mode. Do not use in
DDR mode.
High
High
Input
Channels A and B power-down
Table 7. PDN/OVR_FOR_CTRL_PINS Bit (Set to '1')
CTRL2
CTRL1
PIN DIRECTION
Carries OVR for channel B
Carries OVR for channel A
Output
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8.5.2 Details of Serial Interface
The ADC has a set of internal registers that can be accessed by the serial interface formed by the SEN (serial
interface enable), SCLK (serial interface clock), SDATA (serial interface data) and SDOUT (serial interface data
output) pins. Serial shift of bits into the device is enabled when SEN is low. Serial data SDATA are latched at
every SCLK rising edge when SEN is active (low). The serial data are loaded into the register at every 16th
SCLK rising edge when SEN is low. When 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 interface can work
with SCLK frequencies from 20 MHz down to very low speeds (of a few hertz) and also with non-50% SCLK duty
cycle.
8.5.2.1 Register Initialization
After power-up, the internal registers must be initialized to their default values through a hardware reset by
applying a high pulse on the RESET pin (of durations greater than 10 ns); see Figure 88 and Table 8. If required,
serial interface registers can later be cleared during operation by:
1. Either through a hardware reset or
2. By applying a software reset. When using the serial interface, set the RESET bit (D0 in register address 08h)
high. This setting initializes the internal registers to the default values and then self-resets the RESET bit low.
In this case, the RESET pin is kept low.
Power Supply
AVDD, AVDD3V, DRVDD
t1
RESET
t2
t3
SEN
NOTE: After power-up, the internal registers must be initialized to their default values through a hardware reset by applying a high pulse on
the RESET pin.
Figure 88. Reset Timing Diagram
Table 8. Reset Timing (1)
TEST CONDITIONS
t1
Power-on delay
Delay from AVDD and DRVDD power-up to active RESET pulse
t2
Reset pulse width
Active RESET signal pulse width
t3
Register write delay
Delay from RESET disable to SEN active
(1)
44
MIN
TYP
MAX
UNIT
1
ms
10
ns
1
100
µs
ns
Typical values at +25°C; minimum and maximum values across the full temperature range: TMIN = –40°C to TMAX = +85°C, unless
otherwise noted.
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8.5.2.2 Serial Register Write
The internal register of the ADS42LB49 and ADS42LB69 can be programmed following these steps:
1. Drive SEN pin low
2. Set the R/W bit to ‘0’ (bit A7 of the 8 bit address)
3. Set bit A6 in the address field to ‘0’
4. Initiate a serial interface cycle specifying the address of the register (A5 to A0) whose content must be
written
5. Write 8 bit data which is latched in on the rising edge of SCLK.
Figure 89 and Table 9 illustrate these steps.
Register Address
SDATA
R/W
0
A5
A4
A3
A2
A1
Register Data
A0
D7
D6
D5
D4
D3
=0
D2
D1
D0
tDH
tSCLK
tDSU
SCLK
tSLOADS
tSLOADH
SEN
RESET
Figure 89. Serial Register Write Timing Diagram
Table 9. Serial Interface Timing (Only when Serial Interface is Used) (1)
MIN
MAX
UNIT
20
MHz
fSCLK
SCLK frequency (equal to 1 / tSCLK)
tSLOADS
SEN to SCLK setup time
25
ns
tSLOADH
SCLK to SEN hold time
25
ns
tDSU
SDIO setup time
25
ns
tDH
SDIO hold time
25
ns
(1)
> dc
TYP
Typical values are at +25°C; minimum and maximum values across the full temperature range: TMIN = –40°C to TMAX = +85°C, AVDD3V
= 3.3 V, and AVDD = DRVDD = 1.8 V, unless otherwise noted.
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8.5.2.3 Serial Register Readout
The device includes a mode where the contents of the internal registers can be read back using the SDOUT pin.
This read-back mode may be useful as a diagnostic check to verify the serial interface communication between
the external controller and the ADC.
1. Drive SEN pin low
2. Set the R/W bit (A7) to '1'. This setting disables any further writes to the registers
3. Set bit A6 in the address field to 0.
4. Initiate a serial interface cycle specifying the address of the register (A5 to A0) whose content has to be
read.
5. The device outputs the contents (D7 to D0) of the selected register on the SDOUT pin.
6. The external controller can latch the contents at the SCLK falling edge.
7. To enable register writes, reset the R/W register bit to '0'.
Figure 90 illustrates these steps. When READOUT is disabled, the SDOUT pin is in a high-impedance mode. If
serial readout is not used, the SDOUT pin must float.
Register Address
SDATA
R/W
0
A5
A4
A3
A2
A1
Register Data: don’t care
A0
D7
D6
D5
D4
D3
D2
D1
D0
D1
D0
=1
Register Read Data
SDOUT
D7
D6
D5
D4
D3
D2
SCLK
SEN
Figure 90. Serial Register Readout Timing Diagram
46
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8.6 Register Maps
The serial interface registers are summarized in Table 10.
Table 10. Summary of Serial Interface Registers
REGISTER
ADDRESS
REGISTER DATA
A[7:0] (Hex)
D7
D6
D5
D4
D3
D2
06
1
0
0
0
0
0
07
0
0
0
0
0
STDBY
DATA
FORMAT
DIS CTRL
PINS
08
PDN CHA
PDN CHB
SYNCIN DELAY
0
0
0B
CHA GAIN
CHA GAIN EN
CHBGAIN
CHB GAIN EN
0
1
0F
1
0
1
RESET
FLIP DATA
OVR ON LSB
1
CHA TEST PATTERNS
10
D0
CLK DIV
TEST PAT
ALIGN
0C
0D
D1
0
FAST OVR ON
PIN
CHB TEST PATTERNS
CUSTOM PATTERN 1 (15:8)
11
CUSTOM PATTERN 1 (7:0)
12
CUSTOM PATTERN 2 (15:8)
13
CUSTOM PATTERN 2 (7:0)
14
0
0
0
0
15
0
0
0
0
16
0
0
17
LVDS CLK
STRENGTH EN
18
0
1F
Always write '0'
20
0
LVDS CLK
STRENGTH
LVDS DATA
STRENGTH
DISABLE
OUTPUT CHA
DISABLE
OUTPUT CHB
0
0
0
DDR – QDR
DDR OUTPUT TIMING
0
0
QDR TIMING CHA
INV CLK OUT
CHA
0
QDR TIMING CHB
INV CLK OUT
CHB
FAST OVR THRESHOLD
0
0
0
0
0
0
PDN/OVR FOR
CTRL PINS
Table 11. High-Frequency Modes Summary
REGISTER
ADDRESS
VALUE
0Dh
90h
Enable high-frequency modes for input frequencies greater than 250 MHz.
0Eh
90h
Enable high-frequency modes for input frequencies greater than 250 MHz.
DESCRIPTION
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8.6.1 Description of Serial Interface Registers
8.6.1.1 Register 6 (offset = 06h) [reset = 80h]
Figure 91. Register 6
D7
1
W-1h
D6
0
W-0h
D5
0
W-0h
D4
0
W-0h
D3
0
W-0h
D2
0
W-0h
D1
D0
CLK DIV
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 12. (For example, CONTROL_REVISION Register) Field Descriptions
Bit
Field
Type
Reset
Description
D7
1
W
1h
Always write '1'
D[6:2]
0
W
0h
Always write '0'
0h
Internal clock divider for input sample clock
00 : Divide-by-1 (clock divider bypassed)
01 : Divide-by-2
10 : Divide-by-1
11 : Divide-by-4
D[1:0]
CLK DIV
R/W
8.6.1.2 Register 7 (offset = 07h) [reset = 00h]
Figure 92. Register 7
D7
0
W-0h
D6
0
W-0h
D5
0
W-0h
D4
0
W-0h
D3
0
W-0h
D2
D1
SYNCIN DELAY
R/W-0h
D0
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 13. Register 7 Field Descriptions
Bit
D[7:3]
D[2:0]
48
Field
Type
Reset
Description
0
W
0h
Always write '0'
0h
Controls the delay of the SYNCIN input with respect to the input clock.
Typical values for the expected delay of different settings are:
000 : 0-ps delay
001 : 60-ps delay
010 : 120-ps delay
011 : 180-ps delay
100 : 240-ps delay
101 : 300-ps delay
110 : 360-ps delay
111 : 420-ps delay
SYNCIN DELAY
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8.6.1.3 Register 8 (offset = 08h) [reset = 00h]
Figure 93. Register 8
D7
D6
D5
PDN CHA
PDN CHB
STDBY
R/W-0h
R/W-0h
R/W-0h
D4
DATA
FORMAT
R/W-0h
D3
DIS CTRL
PINS
R/W-0h
D2
TEST PAT
ALIGN
R/W-0h
D1
D0
0
RESET
W-0h
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 14. Register 8 Field Descriptions
Bit
Field
Type
Reset
Description
PDN CHA, PDN CHB
R/W
0h
Power-down channels A and B. Effective only when bit DIS CTRL
PINS is set to '1'.
00 : Normal operation
01 : Channel B powers down. Use only if the QDR interface is
selected. Do not use in the DDR interface.
10 : Channel A powers down. Functions in both QDR and DDR
interfaces.
11 : Both channels power down. Functions in both QDR and DDR
interfaces.
D5
STDBY
R/W
0h
Dual ADC is placed into standby mode
0 : Normal operation
1 : Power down
D4
DATA FORMAT
R/W
0h
Digital output data format
0 : Twos complement
1 : Offset binary
D[7:6]
D3
DIS CTRL PINS
R/W
0h
Disables power-down control from the CTRL1, CTRL2 pins. This bit
also functions as an enable bit for the INV CLK OUT CHA, INV CLK
OUT CHB, and DDR OUTPUT TIMING bits.
0 : CTRL1 and CTRL2 pins control power-down options for channels
A and B
1 : The PDN CHA and PDN CHB register bits determine power-down
options for channels A and B. The INV CLK OUT CHA, INV CLK OUT
CHB, and DDR OUTPUT TIMING register bits become effective.
D2
TEST PAT ALIGN
R/W
0h
Aligns test patterns of two channels
0 : Test patterns for channel A and channel B are free running
1 : Test patterns for both channels are synchronized
D1
0
W
0h
Always write '0'
D0
RESET
R/W
0h
Software reset applied
This bit resets all internal registers to the default values and selfclears to ‘0’
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8.6.1.4 Register B (offset = 0Bh) [reset = 00h]
Figure 94. Register B
D7
D6
D5
CHA GAIN
R/W-0h
D4
D3
D2
CHA GAIN EN
R/W-0h
D1
0
W-0h
D0
FLIP DATA
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 15. Register B Field Descriptions
Bit
Field
Type
Reset
Description
CHA GAIN
R/W
0h
Digital gain for channel A. Effective when the CHA GAIN EN register
bit is set to '1'. Bit descriptions are listed in Table 16.
D2
CHA GAIN EN
R/W
0h
Digital gain enable bit for channel A
0 : Digital gain disabled
1 : Digital gain enabled
D1
0
W
0h
Always write '0'
0h
Flips bit order on the LVDS output bus (LSB versus MSB)
0 : Normal operation
1 : Output bus flipped. In the ADS42LB69, output data bit D0
becomes D15, D1 becomes D14, and so forth.
In the ADS42LB49, output data bit D0 becomes D13, D1 becomes
D12, and so forth.
D[7:3]
D0
FLIP DATA
R/W
Table 16. Digital Gain for Channel A
DIGITAL GAIN FOR
DIGITAL GAIN (dB)
CHANNEL A
50
MAX INPUT
VOLTAGE (VPP)
DIGITAL GAIN FOR
DIGITAL GAIN (dB)
CHANNEL A
MAX INPUT
VOLTAGE (VPP)
00000
0
2.0
01010
1.5
1.7
00001
Do not use
—
01011
2
1.6
00010
Do not use
—
01100
2.5
1.5
00011
–2.0
2.5
01101
3
1.4
00100
–1.5
2.4
01110
3.5
1.3
00101
–1.0
2.2
01111
4
1.25
00110
–0.5
2.1
10000
4.5
1.2
00111
0
2.0
10001
5
1.1
01000
0.5
1.9
10010
5.5
1.05
01001
1
1.8
10011
6
1.0
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8.6.1.5 Register C (offset = 0Ch) [reset = 00h]
Figure 95. Register C
D7
D6
D5
CHB GAIN
R/W-0h
D4
D3
D2
CHB GAIN EN
R/W-0h
D1
D0
OVR ON LSB
R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset
Table 17. Register C Field Descriptions
Bit
D[7:3]
D2
D[1:0]
Field
Type
Reset
Description
CHB GAIN
R/W
0h
Digital gain for channel B. Effective when the CHB GAIN EN register
bit is set to '1'. Bit descriptions are listed in Table 18.
CHB GAIN EN
R/W
0h
Digital gain enable bit for channel B
0 : Digital gain disabled
1 : Digital gain disabled
0h
Functions only with the DDR interface option. Replaces the LSB pair
of 16-bit data (D1, D0) with OVR information. See the Overrange
Indication section.
00 : D1 and D0 are output in the ADS42LB69, NC for the ADS42LB49
01 : Fast OVR in LVDS logic level
10 : Normal OVR in LVDS logic level
11 : D1 and D0 are output in the ADS42LB69, NC for the ADS42LB49
OVR ON LSB
R/W
Table 18. Digital Gain for Channel B
DIGITAL GAIN FOR
DIGITAL GAIN (dB)
CHANNEL B
MAX INPUT
VOLTAGE (VPP)
DIGITAL GAIN FOR
DIGITAL GAIN (dB)
CHANNEL B
MAX INPUT
VOLTAGE (VPP)
00000
0
2.0
01010
1.5
1.7
00001
Do not use
—
01011
2
1.6
00010
Do not use
—
01100
2.5
1.5
00011
–2.0
2.5
01101
3
1.4
00100
–1.5
2.4
01110
3.5
1.3
00101
–1.0
2.2
01111
4
1.25
00110
–0.5
2.1
10000
4.5
1.2
00111
0
2.0
10001
5
1.1
01000
0.5
1.9
10010
5.5
1.05
01001
1
1.8
10011
6
1.0
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8.6.1.6 Register D (offset = 0Dh) [reset = 6Ch]
Figure 96. Register D
D7
0
W-0h
D6
1
W-1h
D5
1
W-1h
D4
0
W-0h
D3
1
W-1h
D2
1
W-1h
D1
0
W-0h
D0
FAST OVR ON PIN
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 19. Register D Field Descriptions
Bit
Field
Type
Reset
Description
D7
0
W
0h
Always write '0'
D[6:5]
1
W
1h
Always write '1'
D4
0
W
0h
Always write '0'
D[3:2]
1
W
1h
Always write '1'
D1
0
W
0h
Always write '0'
D0
FAST OVR ON PIN
R/W
0h
Determines whether normal OVR or fast OVR information is brought on the
OVRx, CTRL1, and CTRL2 pins. See the Overrange Indication section.
0 : Normal OVR available on the OVRx, CTRL1, and CTRL2 pins
1 : Fast OVR available on the OVRx, CTRL1, and CTRL2 pins
8.6.1.7 Register F (offset = 0Fh) [reset = 00h]
Figure 97. Register F
D7
D6
D5
CHA TEST PATTERNS
R/W-0h
D4
D3
D2
D1
CHB TEST PATTERNS
R/W-0h
D0
LEGEND: R/W = Read/Write; -n = value after reset
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Table 20. Register F Field Descriptions
Bit
D[7:4]
D[3:0]
Field
CHA TEST PATTERNS
CHB TEST PATTERNS
Type
R/W
R/W
Reset
Description
0h
Channel A test pattern programmability
0000 : Normal operation
0001 : Outputs all 0s
0010 : Outputs all 1s
0011 : Outputs toggle pattern: In the ADS42LB69, data are an alternating
sequence of 1010101010101010 and 0101010101010101.
In the ADS42LB49, data alternate between 10101010101010 and
01010101010101.
0100 : Output digital ramp: In the ADS42LB69, data increment by 1 LSB
every clock cycle from code 0 to 65535.
In the ADS42LB49 data increment by 1 LSB every fourth clock cycle from
code 0 to 16383.
0101 : Increment pattern: Do not use
0110 : Single pattern: In the ADS42LB69, data are the same as
programmed by the CUSTOM PATTERN 1[15:0] registers bits.
In the ADS42LB49, data are the same as programmed by the CUSTOM
PATTERN 1[15:2] register bits.
0111 : Double pattern: In the ADS42LB69, data alternate between
CUSTOM PATTERN 1[15:0] and CUSTOM PATTERN 2[15:0].
In the ADS42LB49 data alternate between CUSTOM PATTERN 1[15:2]
and CUSTOM PATTERN 2[15:2].
1000 : Deskew pattern: In the ADS42LB69, data are AAAAh. In the
ADS42LB49, data are 3AAAh.
1001 : Do not use
1010 : PRBS pattern: Data are a sequence of pseudo-random numbers
1011 : 8-point sine wave: In the ADS42LB69, data are a repetitive
sequence of the following eight numbers, forming a sine-wave in twos
complement format: 1, 9598, 32768, 55938, 65535, 55938, 32768, and
9598.
In the ADS42LB49, data are a repetitive sequence of the following eight
numbers, forming a sine-wave in twos complement format: 0, 2399, 8192,
13984, 16383, 13984, 8192, and 2399.
0h
Channel B test pattern programmability
0000 : Normal operation
0001 : Outputs all 0s
0010 : Outputs all 1s
0011 : Outputs toggle pattern: In the ADS42LB69, data are an alternating
sequence of 1010101010101010 and 0101010101010101.
In the ADS42LB49, data alternate between 10101010101010 and
01010101010101.
0100 : Output digital ramp: In the ADS42LB69, data increment by 1 LSB
every clock cycle from code 0 to 65535.
In the ADS42LB49 data increment by 1 LSB every fourth clock cycle from
code 0 to 16383.
0101 : Increment pattern: Do not use
0110 : Single pattern: In the ADS42LB69, data are the same as
programmed by the CUSTOM PATTERN 1[15:0] registers bits.
In the ADS42LB49, data are the same as programmed by the CUSTOM
PATTERN 1[15:2] register bits.
0111 : Double pattern: In the ADS42LB69, data alternate between
CUSTOM PATTERN 1[15:0] and CUSTOM PATTERN 2[15:0].
In the ADS42LB49 data alternate between CUSTOM PATTERN 1[15:2]
and CUSTOM PATTERN 2[15:2].
1000 : Deskew pattern: In the ADS42LB69, data are AAAAh. In the
ADS42LB49, data are 3AAAh.
1001 : Do not use
1010 : PRBS pattern: Data are a sequence of pseudo-random numbers
1011 : 8-point sine wave: In the ADS42LB69, data are a repetitive
sequence of the following eight numbers, forming a sine-wave in twos
complement format: 1, 9598, 32768, 55938, 65535, 55938, 32768, and
9598.
In the ADS42LB49, data are a repetitive sequence of the following eight
numbers, forming a sine-wave in twos complement format: 0, 2399, 8192,
13984, 16383, 13984, 8192, and 2399.
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8.6.1.8 Register 10 (offset = 10h) [reset = 00h]
Figure 98. Register 10
D7
D6
D5
D4
D3
CUSTOM PATTERN 1[15:8]
R/W-0h
D2
D1
D0
LEGEND: R/W = Read/Write; -n = value after reset
Table 21. Register 10 Field Descriptions
Bit
D[7:0]
Field
Type
Reset
Description
CUSTOM PATTERN 1[15:8]
R/W
0h
Sets the CUSTOM PATTERN 1[15:8] with these bits for both channels
8.6.1.9 Register 11 (offset = 11h) [reset = 00h]
Figure 99. Register 11
D7
D6
D5
D4
D3
CUSTOM PATTERN 1[7:0]
R/W-0h
D2
D1
D0
LEGEND: R/W = Read/Write; -n = value after reset
Table 22. Register 11 Field Descriptions
Bit
D[7:0]
Field
Type
Reset
Description
CUSTOM PATTERN 1[7:0]
R/W
0h
Sets the CUSTOM PATTERN 1[7:0] with these bits for both channels
8.6.1.10 Register 12 (offset = 12h) [reset = 00h]
Figure 100. Register 12
D7
D6
D5
D4
D3
CUSTOM PATTERN 2[15:8]
R/W-0h
D2
D1
D0
LEGEND: R/W = Read/Write; -n = value after reset
Table 23. Register 12 Field Descriptions
Bit
D[7:0]
Field
Type
Reset
Description
CUSTOM PATTERN 2[15:8]
R/W
0h
Sets the CUSTOM PATTERN 2[15:8] with these bits for both channels
8.6.1.11 Register 13 (offset = 13h) [reset = 00h]
Figure 101. Register 13
D7
D6
D5
D4
D3
CUSTOM PATTERN 2[7:0]
R/W-0h
D2
D1
D0
LEGEND: R/W = Read/Write; -n = value after reset
Table 24. Register 13 Field Descriptions
Bit
D[7:0]
54
Field
Type
Reset
Description
CUSTOM PATTERN 2[7:0]
R/W
0h
Sets the CUSTOM PATTERN 2[7:0] with these bits for both channels
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8.6.1.12 Register 14 (offset = 14h) [reset = 00h]
Figure 102. Register 14
D7
D6
D5
D4
0
0
0
0
W-0h
W-0h
W-0h
W-0h
D3
LVDS CLK
STRENGTH
R/W-0h
D2
LVDS DATA
STRENGTH
R/W-0h
D1
DISABLE
OUTPUT CHA
R/W-0h
D0
DISABLE
OUTPUT CHB
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 25. Register 14 Field Descriptions
Bit
D[7:4]
D3
Field
Type
Reset
Description
0
W
0h
Always write '0'
0h
Increases the LVDS drive strength of the CLKOUTP, CLKOUTM buffers
in the DDR pinout and the DxCLKP, DxCLKM buffers in the QDR pinout
0 : LVDS output clock buffer at default strength used with 100-Ω
external termination
1 : LVDS output clock buffer has double strength used with 50-Ω
external termination. Effective only when the LVDS CLK STRENGTH
EN bit is set to '1'.
LVDS CLK STRENGTH
R/W
D2
LVDS DATA STRENGTH
R/W
0h
Increases the LVDS drive strength
0 : LVDS output data buffers (including frame clock buffers in the QDR
interface) at default strength used with a 100-Ω external termination
1 : LVDS output data buffers (including frame clock buffers in the QDR
interface) at double strength used with a 50-Ω external termination
D1
DISABLE OUTPUT CHA
R/W
0h
Disables LVDS output buffers of channel A
0 : Normal operation
1 : Channel A output buffers are in 3-state
D0
DISABLE OUTPUT CHB
R/W
0h
Disables LVDS output buffers of channel B
0 : Normal operation
1 : Channel B output buffers are in 3-state
8.6.1.13 Register 15 (offset = 15h) [reset = 00h]
Figure 103. Register 15
D7
0
W-0h
D6
0
W-0h
D5
0
W-0h
D4
0
W-0h
D3
0
W-0h
D2
0
W-0h
D1
0
W-0h
D0
DDR – QDR
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 26. Register 15 Field Descriptions
Bit
D[7:1]
D0
Field
Type
Reset
Description
0
W
0h
Always write '0'
DDR – QDR
R/W
0h
Selects output interface between DDR and QDR LVDS mode
0 : QDR LVDS mode
1 : DDR LVDS mode
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8.6.1.14 Register 16 (offset = 16h) [reset = 00h]
Figure 104. Register 16
D7
0
W-0h
D6
0
W-0h
D5
D4
D3
DDR OUTPUT TIMING
R/W-0h
D2
D1
D0
0
W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 27. Register 16 Field Descriptions
Field
Type
Reset
Description
D[7:6]
Bit
0
W
0h
Always write '0'
D[5:1]
DDR OUTPUT TIMING
R/W
0h
Effective only when the DIS CTRL PINS bit is set to '1'.
Bit descriptions are listed in Table 28.
0
W
0h
Always write '0'
D0
Table 28. DDR Output Timing (After Setting Bits DIS CTRL PINS To '1')
DELAY (ps) IN OUTPUT CLOCK WITH RESPECT TO DEFAULT POSITION
56
BIT SETTING
fS = 250 MSPS
fS = 200 MSPS
fS = 150 MSPS
fS = 100 MSPS
00101
–180
–220
–310
–440
00111
–100
–130
–190
–260
00000
0
0
0
0
01101
120
130
170
260
01110
230
240
330
520
01011
320
360
480
740
10100
400
460
620
940
10000
500
600
790
1220
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8.6.1.15 Register 17 (offset = 17h) [reset = 00h]
Figure 105. Register 17
D7
LVDS CLK STRENGTH
EN
R/W-0h
D6
D5
D4
D3
D2
D1
D0
0
QDR OUTPUT TIMING CHA
INVCLK OUT CHA
W-0h
R/W-0h
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 29. Register 17 Field Descriptions
Bit
Field
Type
Reset
Description
D7
LVDS CLK STRENGTH EN
R/W
0h
0 : Default
1 : Enables clock strength programmability with the LVDS CLK
STRENGTH bit
D6
0
W
0h
Always write '0'
QDR OUTPUT TIMING CHA
R/W
0h
Adjusts position of output data clock on channel A with respect to output
data. Bit settings are listed in Table 30.
0h
Inverts polarity of the output clock for channel A (QDR mode only)
0 : Normal operation
1 : Polarity of channel A output clock DACLKP, DACLKM is inverted.
Effective only when the DIS CTRL PINS bit is set to '1'.
D[5:1]
D0
INV CLK OUT CHA
R/W
Table 30. QDR Timing Channel A Timing
DELAY (ps) IN OUTPUT CLOCK WITH RESPECT TO DEFAULT POSITION
BIT SETTING
fS = 250 MSPS
fS = 200 MSPS
fS = 150 MSPS
fS = 100 MSPS
00101
–80
–120
–150
–225
00111
–55
–75
–90
–130
00000
0
0
0
0
01101
55
65
90
130
01110
95
115
165
235
01011
140
165
230
350
10100
180
220
290
450
10000
230
290
370
565
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8.6.1.16 Register 18 (offset = 18h) [reset = 00h]
Figure 106. Register 18
D7
0
W-0h
D6
0
W-0h
D5
D4
D3
D2
QDR OUTPUT TIMING CHB
R/W-0h
D1
D0
INVCLK OUT CHB
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 31. Register 18 Field Descriptions
Field
Type
Reset
Description
D[7:6]
Bit
0
W
0h
Always write '0'
D[5:1]
QDR OUTPUT TIMING CHB
R/W
0h
Adjusts position of output data clock on channel B with respect to output
data. Bit settings are listed in Table 32.
0h
Inverts output clock polarity for channel B in QDR mode, or output clock
CLKOUTP, CLKOUTM in DDR mode.
0 : Normal operation
1 : In QDR mode, the polarity of the channel B output clock DBCLKP,
DBCLKM is inverted. Effective only when the DIS CTRL PINS bit is set
to '1'. In DDR mode, the output clock polarity of CLKOUTP, CLKOUTM
is inverted.
D0
INV CLK OUT CHB
R/W
Table 32. QDR Timing Channel B Timing
DELAY (ps) IN OUTPUT CLOCK WITH RESPECT TO DEFAULT POSITION
58
BIT SETTING
fS = 250 MSPS
fS = 200 MSPS
fS = 150 MSPS
fS = 100 MSPS
00101
–80
–120
–150
–225
00111
–55
–75
–90
–130
00000
0
0
0
0
01101
55
65
90
130
01110
95
115
165
235
01011
140
165
230
350
10100
180
220
290
450
10000
230
290
370
565
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8.6.1.17 Register 1F (offset = 1Fh) [reset = 7Fh]
Figure 107. Register 1F
D7
0
W-0h
D6
D5
D4
D3
FAST OVR THRESHOLD
R/W-0h
D2
D1
D0
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 33. Register 1F Field Descriptions
Bit
Field
Type
Reset
Description
D7
0
W
1h
Always write '0'
Default value of this bit is '1'. Always write this bit to '0' when fast
OVR thresholds are programmed.
0h
The device has a fast OVR mode that indicates an overload
condition at the ADC input. The input voltage level at which the
overload is detected is referred to as the threshold and is
programmable using the FAST OVR THRESHOLD bits. FAST
OVR is triggered nine output clock cycles after the overload
condition occurs. The threshold at which fast OVR is triggered is
(full-scale × [the decimal value of the FAST OVR THRESHOLD
bits] / 127). See the Overrange Indication section for details.
D[6:0]
FAST OVR THRESHOLD
R/W
8.6.1.18 Register 20 (offset = 20h) [reset = 00h]
Figure 108. Register 20
D7
D6
D5
D4
D3
D2
D1
0
0
0
0
0
0
0
W-0h
W-0h
W-0h
W-0h
W-0h
W-0h
W-0h
D0
PDN/OVR FOR
CTRL PINS
R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset
Table 34. Register 20 Field Descriptions
Bit
D[7:1]
D0
Field
Type
Reset
Description
0
W
0h
Always write '0'
0h
Determines if the CTRL1, CTRL2 pins are power-down control or OVR
outputs
0 : CTRL1 and CTRL2 pins function as input pins to control power-down
operation.
1 : CTRL1 and CTRL2 pins function as output pins for overrange
indications of channels A and B, respectively. The PDN CH A, PDN CH
B register bits along with DIS CTRL PINS can be used for power-down
operation.
PDN/OVR FOR CTRL PINS
R/W
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9 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.
9.1 Application Information
To obtain the best performance in an application, careful consideration must be given to the design of the input
analog circuit and common-mode, clock circuit, and power-supply rails. The Typical Application section discusses
these critical design considerations in detail.
9.2 Typical Application
Because the ADS42LBx9 is a dual-channel device, it can be used in a dual-channel superheterodyne receiver,
as shown in Figure 109. In a superheterodyne receiver, the high-frequency RF signal is first mixed down to a
lower Intermediate frequency (IF). The ADS42LBxx can be used in the IF stage to sample and digitize the IF
signal. The digital data can be encoded either in offset binary or twos complement format and transmitted to a
field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC). Inside the FPGA or ASIC,
the digital data are down-converted to the baseband frequency with a digital mixer and numerically controlled
oscillator (NCO).
Mixer
RF1
Ch A
Baseband Processor
(FPGA, ASIC)
Ch B
RF2
IF Amplifier
IF Filter
ADS42LBxx
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LO
Figure 109. The ADS42LBx9 in a Dual-Channel Superheterodyne Receiver
9.2.1 Design Requirements
Specific design requirements are provided in Table 35.
Table 35. ADS42LBx9 Design Requirements
DESIGN PARAMETER
VALUE
fSAMPLING
250 MSPS
IF
10 MHz (Figure 123), 170 MHz (Figure 124)
SNR
> 72 dBc
SFDR
> 80 dBc
HDn
> 90 dBc
9.2.2 Detailed Design Procedure
The choice of drive circuit at the analog and clock inputs can degrade the performance of the ADC. In order to
obtain the design specifications given in Table 35, the following design guidelines discussed in this section must
be followed.
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9.2.2.1 Analog Input
The analog input pins have analog buffers (running from the AVDD3V supply) that internally drive the differential
sampling circuit. As a result of the analog buffer, the input pins present high input impedance to the external
driving source (at dc, a 10-kΩ differential input resistance is provided in shunt with a 4-pF differential input
capacitance). The buffer helps isolate the external driving source from the switching currents of the sampling
circuit. This buffering makes driving the buffered inputs easier than when compared to an ADC without the buffer.
The input common-mode is set internally using a 5-kΩ resistor from each input pin to VCM so the input signal
can be ac-coupled to the pins. Each input pin (INP, INM) must swing symmetrically between VCM + 0.5 V and
VCM – 0.5 V, resulting in a 2-VPP differential input swing. When programmed for 2.5-VPP full-scale, each input pin
must swing symmetrically between VCM + 0.625 V and VCM – 0.625 V.
The input sampling circuit has a high 3-dB bandwidth that extends up to 900 MHz (measured with a 50-Ω source
driving a 50-Ω termination between INP and INM). The dynamic offset of the first-stage sub-ADC limits the
maximum analog input frequency to approximately 250 MHz (with a 2.5-VPP full-scale amplitude) and to
approximately 400 MHz (with a 2-VPP full-scale amplitude). This maximum analog input frequency is different
than the analog bandwidth of 900 MHz, which is only an indicator of signal amplitude versus frequency.
9.2.2.1.1 Drive Circuit Requirements
For optimum performance, the analog inputs must be driven differentially. This technique improves the commonmode noise immunity and even-order harmonic rejection. A small resistor (10 Ω) in series with each input pin is
recommended to damp out ringing caused by package parasitics.
Figure 110, Figure 111, and Figure 112 show the differential impedance (ZIN = RIN || CIN) at the ADC input pins.
The presence of the analog input buffer results in an almost constant input capacitance up to 1 GHz.
INxP(1)
ZIN(2)
RIN
CIN
INxM
(1) X = A or B.
(2) ZIN = RIN || (1 / jωCIN).
Figure 110. ADC Equivalent Input Impedance
5
Differential Capacitance, Cin (pF)
Differential Resistance, Rin (kΩ)
10
1
0.1
0.05
0
200
400
600
Frequency (MHz)
800
1000
4
3
2
1
0
0
200
G073
Figure 111. ADC Analog Input Resistance (RIN) Across
Frequency
400
600
Frequency (MHz)
800
1000
G074
Figure 112. ADC Analog Input Capacitance (CIN) Across
Frequency
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9.2.2.1.2 Driving Circuit
An example driving circuit configuration is shown in Figure 113. To optimize even-harmonic performance at high
input frequencies (greater than the first Nyquist), the use of back-to-back transformers is recommended, as
shown in Figure 113. Note that the drive circuit is 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. If HD2 optimization is
a concern, using a 10-Ω series resistor on the INP side and a 9.5-Ω series resistor on the INM side may help
improve HD2 by 2 dB to 3 dB at a 85-dBFS level on a 170-MHz IF. An additional R-C-R (39 Ω - 6.8 pF - 39 Ω)
circuit placed near device pins helps further improve HD3.
0.1 PF
0.1 PF
10 :
INP
RINT
39 :
25 :
0.1 PF
6.8 pF
25 :
RINT
39 :
INM
1:1
10 : (or 9.5 :)
0.1 PF
1:1
Device
Figure 113. Drive Circuit for Input Frequencies up to 250 MHz
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 Figure 113. The center point of this termination is connected
to ground to improve the balance between the P (positive) and M (negative) sides. The values of the terminations
between the transformers and on the secondary side must be chosen to obtain an effective 50 Ω (for a 50-Ω
source impedance). For high input frequencies (>250MHz), the R-C-R circuit can be removed as indicated in
Figure 114.
0.1 PF
0.1 PF
10 :
INP
RINT
0.1 PF
25 :
25 :
RINT
INM
1:1
1:1
0.1 PF
10 : (or 9.5 :)
Device
Figure 114. Drive Circuit for Input Frequencies > 250 MHz
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9.2.2.1.3 Using the ADS42LBx9 In Time-Domain, Low-Frequency Pulse Applications
The analog buffers inside the device are implemented to provide excellent linearity over a wide range of
frequencies. However, at very low frequencies (< 100 kHz) the buffer presents a high-pass response, as shown
in Figure 115 and Figure 116. This response does not affect most frequency-domain applications, but can require
compensation techniques for time-domain, dc-coupled applications. Application report SBAA220 discusses
simple techniques to compensate for the analog buffer response.
Device
Analog Input
(INxP-INxM)
Buffer Output
Sampling
Switch
Sampling
Cap
Analog Buffer
Figure 115. Analog Buffer in the ADS42LBx9
0.1
Buffer Response (dB)
0
-0.1
-0.2
-0.3
-0.4
-0.5
0
250
500
750 1000 1250 1500 1750 2000 2250 2500
Frequency (KHz)
G075
Figure 116. Buffer Response at Very Low Input Frequencies
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9.2.2.2 Clock Input
The device 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 1.4 V
using internal 5-kΩ resistors. The self-bias clock inputs of the ADS42LB69 and ADS42LB49 can be driven by the
transformer-coupled, sine-wave clock source or by the ac-coupled, LVPECL and LVDS clock sources, as shown
in Figure 117, Figure 118, and Figure 119. Figure 119 details the internal clock buffer.
Note:
RT = termination resistor, if necessary.
0.1 mF
0.1 mF
Zo
CLKP
Differential
Sine-Wave
Clock Input
CLKP
RT
Typical LVDS
Clock Input
0.1 mF
100 W
CLKM
Device
0.1 mF
Zo
CLKM
Figure 117. Differential Sine-Wave Clock Driving
Circuit
Zo
Device
Figure 118. LVDS Clock Driving Circuit
0.1 mF
CLKP
150 W
Typical LVPECL
Clock Input
100 W
Zo
0.1 mF
CLKM
Device
150 W
Figure 119. LVPECL Clock Driving Circuit
Clock Buffer
LPKG
2 nH
20 W
CLKP
CBOND
1 pF
5 kW
RESR
100 W
LPKG
2 nH
CEQ
CEQ
1.4 V
20 W
5 kW
CLKM
CBOND
1 pF
RESR
100 W
NOTE: CEQ is 1 pF to 3 pF and is the equivalent input capacitance of the clock buffer.
Figure 120. Internal Clock Buffer
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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 121. However, for best performance the clock inputs must be driven differentially,
thereby reducing susceptibility to common-mode noise. For high input frequency sampling, TI recommends using
a clock source with very low jitter. Band-pass filtering of the clock source can help reduce the effects of jitter.
There is no change in performance with a non-50% duty cycle clock input.
0.1 mF
CMOS
Clock Input
CLKP
0.1 mF
CLKM
Device
Figure 121. Single-Ended Clock Driving Circuit
9.2.2.3 SNR and Clock Jitter
The signal-to-noise ratio (SNR) of the ADC is limited by three different factors, as shown in Equation 3.
Quantization noise is typically not noticeable in pipeline converters and is 96 dBFS for a 16-bit ADC. Thermal
noise limits SNR at low input frequencies and clock jitter sets SNR for higher input frequencies.
SNRQuantization _ Noise
æ
SNR ADC [dBc] = -20 ´ log çç 10 20
è
2
2
2
ö æ
SNRThermalNoise ö æ
SNRJitter ö
÷÷ + ç 10 ÷ + ç 10 ÷
20
20
ø è
ø
ø è
SNR limitation is a result of sample clock jitter and can be calculated by Equation 4:
SNRJitter [dBc] = -20 ´ log(2p ´ fIN ´ tJitter)
(3)
(4)
The total clock jitter (TJitter) has three components: the internal aperture jitter (85 fS for the device) is set by the
noise of the clock input buffer, the external clock jitter, and the jitter from the analog input signal. TJitter can be
calculated by Equation 5:
TJitter =
(TJitter,Ext.Clock_Input)2 + (TAperture_ADC)2
(5)
External clock jitter can be minimized by using high-quality clock sources and jitter cleaners as well as band-pass
filters at the clock input while a faster clock slew rate improves ADC aperture jitter. The device has a 74.1-dBFS
thermal noise and an 85-fS internal aperture jitter. The SNR value depends on the amount of external jitter for
different input frequencies, as shown in Figure 122.
76
SNR (dBFS)
74
72
35 fs
70
50 fs
68
100 fs
150 fs
66
200 fs
64
10
100
1000
Fin (MHz)
Figure 122. SNR versus Input Frequency and External Clock Jitter
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9.2.3 Application Curves
0
0
fIN = 10 MHz
SFDR = 88 dBc
SNR = 74 dBFS
SINAD = 73.9 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 102 dBc
−40
−60
−80
−100
−120
−40
−60
−80
−100
0
25
50
75
Frequency (MHz)
100
Figure 123. FFT for 10-MHz Input Signal
66
fIN = 170 MHz
SFDR = 90 dBc
SNR = 73.1 dBFS
SINAD = 73 dBFS
THD = 87 dBc
SFDR Non HD2, HD3
= 100 dBc
−20
Amplitude (dBFS)
Amplitude (dBFS)
−20
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125
−120
0
25
G001
50
75
Frequency (MHz)
100
125
G002
Figure 124. FFT for 170-MHz Input Signal
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10 Power Supply Recommendations
Three different power-supply rails are required for the ADS42LBx9:
• A 3.3-V AVDD is used to power the analog buffers.
• A 1.8-V AVDD is used to power the analog core of the ADC.
• A 1.8-V DRVDD is used to power the digital core of the ADC.
TI recommends providing the 1.8-V digital and analog supplies from separate sources because of the switching
activities on the digital rail. An example power-supply scheme suitable for the ADS42LBx9 device family is shown
in Figure 125. In this example supply scheme, AVDD is provided from a dc-dc converter and an low-dropout
(LDO) regulator to increase the efficiency of the implementation. Where cost and area rather than power-supply
efficiency are the main design goals, AVDD can be provided using only the LDO.
3.3 V (340 mA)
AVDD3V
3.3 V
DC-DC Converter
2V
1.8 V (182 mA)
AVDD
LDO
1.8 V (245 mA)
DC-DC Converter
DRVDD
Figure 125. Example Power-Supply Scheme
11 Layout
11.1 Layout Guidelines
•
•
•
•
•
The length of the positive and negative traces of a differential pair must be matched to within 2 mils of each
other.
Each differential pair length must be matched within 10 mils of each other.
When the ADC is used on the same printed circuit board (PCB) with a digital intensive component [such as a
field-programmable gate array (FPGA) or application-specific integrated circuit (ASIC)], use separate digital
and analog ground planes to minimize undesired coupling. Note that these ground planes must not overlap.
Connect decoupling capacitors directly to ground and place these capacitors close to the ADC power pins
and the power-supply pins to filter high-frequency current transients directly to the ground plane, as illustrated
in Figure 126.
Ground and power planes must be wide enough to keep the impedance very low. In a multilayer PCB,
dedicate one layer to ground and another to power planes.
AVDD
DRVDD
10 F
10 F
Place the decoupling capacitor close to
the power-supply pin.
10 F
10 F
Place the decoupling capacitor close to
the ADC power-supply pin.
Device
Figure 126. Recommended Placement of Power-Supply Decoupling Capacitors
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Product Folder Links: ADS42LB49 ADS42LB69
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11.2 Layout Example
Figure 127. Example Layout
68
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Product Folder Links: ADS42LB49 ADS42LB69
ADS42LB49, ADS42LB69
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SLAS904F – OCTOBER 2012 – REVISED MAY 2016
Layout Example (continued)
Copper
Layer 1 Signal
Dielectric
GND
Dielectric
PWR
Dielectric
PWR
Dielectric
GND
Dielectric
Layer 6 Signal
Dielectric = 0.011 inches
Copper = 0.25 oz
Figure 128. Example PCB Layer Stack
Copyright © 2012–2016, Texas Instruments Incorporated
Product Folder Links: ADS42LB49 ADS42LB69
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www.ti.com
12 Device and Documentation Support
12.1 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 36. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
ADS42LB49
Click here
Click here
Click here
Click here
Click here
ADS42LB69
Click here
Click here
Click here
Click here
Click here
12.2 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.
12.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
12.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 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.
70
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Product Folder Links: ADS42LB49 ADS42LB69
PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
ADS42LB49IRGCR
ACTIVE
VQFN
RGC
64
2000
RoHS & Green
Call TI | NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ42LB49
ADS42LB49IRGCT
ACTIVE
VQFN
RGC
64
250
RoHS & Green
Call TI | NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ42LB49
ADS42LB69IRGCR
ACTIVE
VQFN
RGC
64
2000
RoHS & Green
Call TI | NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ42LB69
ADS42LB69IRGCT
ACTIVE
VQFN
RGC
64
250
RoHS & Green
Call TI | NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ42LB69
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of