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ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
ADS41xx 14-/12-Bit, 65-/125-MSPS, Ultra Low-Power ADC
1 Features
3 Description
•
The ADS412x and ADS414x are lower-sampling
speed variants in the ADS41xx family of analog-todigital converters (ADCs). These devices use
innovative design techniques to achieve high dynamic
performance, while consuming extremely low power
at 1.8-V supply. The devices are well-suited for multicarrier, wide bandwidth communications applications.
1
•
•
•
•
•
•
Ultralow Power with 1.8-V Single Supply:
– 103-mW Total Power at 65MSPS
– 153-mW Total Power at 125 MSPS
High Dynamic Performance:
– SNR: 72.2 dBFS at 170 MHz
– SFDR: 81 dBc at 170 MHz
Dynamic Power Scaling with Sample Rate
Output Interface:
– Double Data Rate (DDR) LVDS with
Programmable Swing and Strength
– Standard Swing: 350 mV
– Low Swing: 200 mV
– Default Strength: 100-Ω Termination
– 2x Strength: 50-Ω Termination
– 1.8-V Parallel CMOS Interface Also Supported
Programmable Gain up to 6 dB for SNR/SFDR
Trade-Off
DC Offset Correction
Supports Low Input Clock Amplitude Down to 200
mVPP
2 Applications
•
•
•
Wireless Communications Infrastructure
Software-Defined Radio
Power Amplifier Linearization
The ADS412x/4x have fine gain options that can be
used to improve SFDR performance at lower fullscale input ranges, especially at high input
frequencies. They include a dc offset correction loop
that can be used to cancel the ADC offset. At lower
sampling rates, the ADC automatically operates at
scaled down power with no loss in performance.
The ADS412x/4x are available in a compact VQFN48 package and are specified over the industrial
temperature range (–40°C to +85°C).
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
ADS4122
ADS4125
ADS4142
VQFN (48)
7.00 mm x 7.00 mm
ADS4145
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
ADS4122 Block Diagram
ADS4122
VCM
Reference
LVDS
D0_D1P
D0_D1M
INP
Sampling
Circuit
12-bit ADC
INM
D10_D11P
D10_D11M
CLKP
CLK
Gen
CLKM
CLKOUTP
CLKOUTM
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.
ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison ...............................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
7
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
Absolute Maximum Ratings ...................................... 7
ESD Ratings.............................................................. 7
Recommended Operating Conditions....................... 7
Thermal Information .................................................. 8
Electrical Characteristics: ADS412x ......................... 8
Electrical Characteristics: ADS414x ....................... 10
Electrical Characteristics: General .......................... 12
Digital Characteristics ............................................. 13
Timing Requirements: LVDS and CMOS Modes.... 14
Serial Interface Timing Characteristics ................. 15
Reset Timing Requirements ................................. 15
Timing Characteristics at Lower Sampling
Frequencies ............................................................. 15
7.13 Typical Characteristics .......................................... 19
8
Detailed Description ............................................ 34
8.1 Overview ................................................................. 34
8.2 Functional Block Diagrams .................................... 35
8.3
8.4
8.5
8.6
9
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
Register Maps .........................................................
36
39
45
47
Application and Implementation ........................ 54
9.1 Application Information............................................ 54
9.2 Typical Application .................................................. 59
10 Power Supply Recommendations ..................... 61
10.1 Sharing DRVDD and AVDD Supplies ................... 61
10.2 Using DC-DC Power Supplies .............................. 61
10.3 Power Supply Bypassing ...................................... 61
11 Layout................................................................... 61
11.1 Layout Guidelines ................................................. 61
11.2 Layout Example .................................................... 62
12 Device and Documentation Support ................. 63
12.1
12.2
12.3
12.4
12.5
12.6
12.7
Device Support......................................................
Documentation Support ........................................
Related Links ........................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
63
65
65
65
65
65
66
13 Mechanical, Packaging, and Orderable
Information ........................................................... 66
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (March 2011) to Revision B
•
2
Page
Added Pin Configuration and Functions section, Handling Rating table, Feature Descriptionsection, Device
Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout
section, Device and Documentation Supportsection, and Mechanical, Packaging, and Orderable Information section ...... 1
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SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
5 Device Comparison
FAMILY
65 MSPS
125 MSPS
160 MSPS
250 MSPS
ADS412x
12-Bit Family
ADS4122
ADS4125
ADS4126
ADS414x
14-Bit Family
ADS4142
ADS4145
9-Bit
—
11-Bit
—
WITH ANALOG INPUT BUFFERS
200 MSPS
250 MSPS
ADS4129
—
ADS41B29
ADS4146
ADS4149
—
ADS41B49
—
—
—
—
ADS58B19
—
—
—
ADS58B18
—
Copyright © 2011–2016, Texas Instruments Incorporated
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3
ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
www.ti.com
6 Pin Configuration and Functions
37 D2_D3_M
38 D2_D3_P
39 D4_D5_M
40 D4_D5_P
41 D6_D7_M
42 D6_D7_P
43 D8_D9_M
44 D8_D9_P
45 D10_D11_M
46 D10_D11_P
48 D12_D13_P
47 D12_D13_M
ADS414x RGZ Package
48-Pin VQFN With Exposed Thermal Pad
LVDS Mode - Top View
37 D0_D1_M
38 D0_D1_P
39 D2_D3_M
40 D2_D3_P
41 D4_D5_M
42 D4_D5_P
43 D6_D7_M
44 D6_D7_P
45 D8_D9_M
46 D8_D9_P
47 D10_D11_M
48 D10_D11_P
ADS412x RGZ Package
48-Pin VQFN With Exposed Thermal Pad
LVDS Mode - Top View
DRGND
1
36 DRGND
DRGND
1
36 DRGND
DRVDD
2
35 DRVDD
DRVDD
2
35 DRVDD
OVR_SDOUT
3
34 NC
OVR_SDOUT
3
34 D0_D1_P
CLKOUTM
4
33 NC
CLKOUTM
4
33 D0_D1_M
32 NC
CLKOUTP
5
32 NC
31 NC
DFS
6
OE
7
30 RESET
AVDD
8
29 SCLK
AGND
9
28 SDATA
CLKM 11
26 AVDD
AGND 12
26 AVDD
AGND 12
25 AGND
AVDD 24
AVDD 22
RESERVED 23
NC 21
AVDD 20
AGND 19
AVDD 18
AGND 17
INM 16
INP 15
VCM 13
AGND 14
25 AGND
27 SEN
CLKM 11
AVDD 24
27 SEN
RESERVED 23
CLKP 10
CLKP 10
AVDD 22
28 SDATA
NC 21
9
AVDD 20
29 SCLK
AGND 19
8
AVDD 18
AGND
30 RESET
AGND 17
AVDD
7
VCM 13
OE
31 NC
Thermal Pad
Thermal Pad
INM 16
6
INP 15
DFS
5
AGND 14
CLKOUTP
The thermal pad is connected to DRGND.
Pin Functions - LVDS Mode
PIN
I/O
DESCRIPTION
NAME
ADS412x
ADS414x
AGND
9, 12, 14, 17, 19, 25
9, 12, 14, 17, 19, 25
I
Analog ground
AVDD
8, 18, 20, 22, 24, 26
8, 18, 20, 22, 24, 26
I
1.8-V analog power supply
CLKM
11
11
I
Differential clock input, complement
CLKP
10
10
I
Differential clock input, true
CLKOUTM
4
4
O
Differential output clock, complement
CLKOUTP
5
5
O
Differential output clock, true
D0_D1_M
37
33
O
Differential output data D0 and D1 multiplexed, complement
D0_D1_P
38
34
O
Differential output data D0 and D1 multiplexed, true
D2_D3_M
39
37
O
Differential output data D2 and D3 multiplexed, complement
D2_D3_P
40
38
O
Differential output data D2 and D3 multiplexed, true
D4_D5_M
41
39
O
Differential output data D4 and D5 multiplexed, complement
D4_D5_P
42
40
O
Differential output data D4 and D5 multiplexed, true
D6_D7_M
43
41
O
Differential output data D6 and D7 multiplexed, complement
D6_D7_P
44
42
O
Differential output data D6 and D7 multiplexed, true
D8_D9_M
45
43
O
Differential output data D8 and D9 multiplexed, complement
D8_D9_P
46
44
O
Differential output data D8 and D9 multiplexed, true
D10_D11_M
47
45
O
Differential output data D10 and D11 multiplexed, complement
D10_D11_P
48
46
O
Differential output data D10 and D11 multiplexed, true
D12_D13_M
—
47
O
Differential output data D12 and D13 multiplexed, complement
D12_D13_P
—
48
O
Differential output data D12 and D13 multiplexed, true
DFS
6
6
I
Data format select input. This pin sets the DATA FORMAT (twos complement or offset binary)
and the LVDS/CMOS output interface type. See Table 4 for detailed information.
DRGND
1, 36, PAD
1, 36, PAD
I
Digital and output buffer ground
DRVDD
2, 35
2, 35
I
1.8-V digital and output buffer supply
INM
16
16
I
Differential analog input, negative
INP
15
15
I
Differential analog input, positive
4
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SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Pin Functions - LVDS Mode (continued)
PIN
I/O
NAME
DESCRIPTION
ADS412x
ADS414x
NC
21, 31, 32, 33, 34
21, 31, 32
–
Do not connect
OE
7
7
I
Output buffer enable input, active high; this pin has an internal 180-kΩ pull-up resistor to DRVDD.
OVR_SDOUT
3
3
O
This pin functions as an out-of-range indicator after reset, when register bit
READOUT = 0, and functions as a serial register readout pin when READOUT = 1.
RESERVED
23
23
I
Digital control pin, reserved for future use
RESET
30
30
I
Serial interface RESET input.
When using the serial interface mode, the internal registers must initialize through hardware
RESET by applying a high pulse on this pin or by using the software reset option; refer to the
Serial Interface section.
When RESET is tied high, the internal registers are reset to the default values. In this condition,
SEN can be used as an analog control pin.
RESET has an internal 180-kΩ pull-down resistor.
SCLK
29
29
I
This pin functions as a serial interface clock input when RESET is low. When RESET is high,
SCLK has no function and should be tied to ground. This pin has an internal 180-kΩ pull-down
resistor.
SDATA
28
28
I
This pin functions as a serial interface data input when RESET is low. When RESET is high,
SDATA functions as a STANDBY control pin (see Table 6). This pin has an internal 180-kΩ pulldown resistor.
SEN
27
27
I
This pin functions as a serial interface enable input when RESET is low. When RESET is high,
SEN has no function and should be tied to AVDD. This pin has an internal 180-kΩ pull-up resistor
to AVDD.
VCM
13
13
O
Outputs the common-mode voltage (0.95 V) that can be used externally to bias the analog input
pins.
37 D2
38 D3
39 D4
40 D5
41 D6
42 D7
43 D8
44 D9
45 D10
46 D11
47 D12
48 D13
ADS414x RGZ Package
48-PIN VQFN With Exposed Thermal Pad
CMOS Mode -Top View
37 D0
38 D1
39 D2
40 D3
41 D4
42 D5
43 D6
44 D7
45 D8
46 D9
47 D10
48 D11
ADS412x RGZ Package
48-PIN VQFN With Exposed Thermal Pad
CMOS Mode - Top View
DRGND
1
36 DRGND
DRGND
1
36 DRGND
DRVDD
2
35 DRVDD
DRVDD
2
35 DRVDD
OVR_SDOUT
3
34 NC
OVR_SDOUT
3
34 D1
UNUSED
4
33 NC
UNUSED
4
33 D0
CLKOUT
5
32 NC
CLKOUT
5
32 NC
DFS
6
31 NC
DFS
6
OE
7
30 RESET
OE
7
30 RESET
AVDD
8
29 SCLK
AVDD
8
29 SCLK
AGND
9
9
28 SDATA
31 NC
Thermal Pad
Thermal Pad
AVDD 24
AVDD 22
RESERVED 23
NC 21
AVDD 20
AGND 19
AVDD 18
AGND 17
INM 16
INP 15
VCM 13
AGND 14
AVDD 24
AVDD 22
25 AGND
RESERVED 23
AGND 12
NC 21
25 AGND
AVDD 20
26 AVDD
AGND 12
AGND 19
CLKM 11
AVDD 18
26 AVDD
AGND 17
27 SEN
CLKM 11
INM 16
CLKP 10
INP 15
27 SEN
VCM 13
CLKP 10
AGND 14
28 SDATA
AGND
The thermal pad is connected to DRGND.
Pin Functions - CMOS Mode
PIN
I/O
DESCRIPTION
NAME
ADS412x
ADS414x
AVDD
8, 18, 20, 22, 24, 26
8, 18, 20, 22, 24, 26
I
1.8-V analog power supply
AGND
9, 12, 14, 17, 19, 25
9, 12, 14, 17, 19, 25
I
Analog ground
CLKM
11
11
I
Differential clock input, complement
CLKP
10
10
I
Differential clock input, true
CLKOUT
5
5
O
CMOS output clock
D0
37
33
O
12-bit/14-bit CMOS output data
D1
38
34
O
12-bit/14-bit CMOS output data
D2
39
37
O
12-bit/14-bit CMOS output data
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Pin Functions - CMOS Mode (continued)
PIN
I/O
NAME
DESCRIPTION
ADS412x
ADS414x
D3
40
38
O
12-bit/14-bit CMOS output data
D4
41
39
O
12-bit/14-bit CMOS output data
D5
42
40
O
12-bit/14-bit CMOS output data
D6
43
41
O
12-bit/14-bit CMOS output data
D7
44
42
O
12-bit/14-bit CMOS output data
D8
45
43
O
12-bit/14-bit CMOS output data
D9
46
44
O
12-bit/14-bit CMOS output data
D10
47
45
O
12-bit/14-bit CMOS output data
D11
48
46
O
12-bit/14-bit CMOS output data
D12
—
47
O
12-bit/14-bit CMOS output data
D13
—
48
O
12-bit/14-bit CMOS output data
DFS
6
6
I
Data format select input. This pin sets the DATA FORMAT (twos complement or offset binary)
and the LVDS/CMOS output interface type. See Table 4 for detailed information.
DRGND
1, 36, PAD
1, 36, PAD
I
Digital and output buffer ground
DRVDD
2, 35
2, 35
I
1.8-V digital and output buffer supply
INM
16
16
I
Differential analog input, negative
INP
15
15
I
Differential analog input, positive
NC
21, 31, 32, 33, 34
21, 31, 32
–
Do not connect
OE
7
7
I
Output buffer enable input, active high; this pin has an internal 180-kΩ pull-up resistor to DRVDD.
OVR_SDOUT
3
3
O
This pin functions as an out-of-range indicator after reset, when register bit
READOUT = 0, and functions as a serial register readout pin when READOUT = 1.
RESERVED
23
23
I
Digital control pin, reserved for future use
RESET
30
30
I
Serial interface RESET input.
When using the serial interface mode, the internal registers must initialize through hardware
RESET by applying a high pulse on this pin or by using the software reset option; refer to the
Serial Interface section.
When RESET is tied high, the internal registers are reset to the default values. In this condition,
SEN can be used as an analog control pin.
RESET has an internal 180-kΩ pull-down resistor.
SCLK
29
29
I
This pin functions as a serial interface clock input when RESET is low. When RESET is high,
SCLK has no function and should be tied to ground. This pin has an internal 180-kΩ pull-down
resistor.
SDATA
28
28
I
This pin functions as a serial interface data input when RESET is low. When RESET is high,
SDATA functions as a STANDBY control pin (see Table 6). This pin has an internal 180-kΩ pulldown resistor.
SEN
27
27
I
This pin functions as a serial interface enable input when RESET is low. When RESET is high,
SEN has no function and should be tied to AVDD. This pin has an internal 180-kΩ pull-up resistor
to AVDD.
UNUSED
4
4
–
Unused pin in CMOS mode
VCM
13
13
O
Outputs the common-mode voltage (0.95 V) that can be used externally to bias the analog input
pins.
6
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SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
7 Specifications
7.1 Absolute Maximum Ratings
Over operating free-air temperature range, unless otherwise noted. (1)
MIN
MAX
UNIT
Supply voltage, AVDD
–0.3
2.1
V
Supply voltage, DRVDD
–0.3
2.1
V
Voltage between AGND and DRGND
–0.3
0.3
V
0
2.1
V
Voltage between AVDD to DRVDD (when AVDD leads DRVDD)
Voltage between DRVDD to AVDD (when DRVDD leads AVDD)
Voltage applied to input pins
0
2.1
V
INP, INM
–0.3
minimum (1.9, AVDD + 0.3)
V
CLKP, CLKM (2), DFS, OE
–0.3
AVDD + 0.3
V
RESET, SCLK, SDATA, SEN
–0.3
3.9
V
–40
85
°C
125
°C
150
°C
Operating free-air temperature, TA
Operating junction temperature, TJ
Storage temperature, Tstg
(1)
(2)
–65
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.
When AVDD is turned off, it is recommended to switch off the input clock (or ensure the voltage on CLKP, CLKM is less than |0.3 V|.
This prevents the ESD protection diodes at the clock input pins from turning on.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
Over operating free-air temperature range, unless otherwise noted.
MIN
NOM
MAX
UNIT
SUPPLIES
AVDD
Analog supply voltage
1.7
1.8
1.9
V
DRVDD
Digital supply voltage
1.7
1.8
1.9
V
ANALOG INPUTS
Differential input voltage range (1)
2
Input common-mode voltage
VPP
VCM ± 0.05
V
Maximum analog input frequency with 2-VPP input amplitude (2)
400
MHz
Maximum analog input frequency with 1-VPP input amplitude (2)
800
MHz
CLOCK INPUT
Input clock sample rate
ADS4122/ADS4142, low-speed mode enabled by
default
20
65
ADS4125/ADS4145, low-speed mode enabled
20
80
ADS4125/ADS4145, low-speed mode disabled
>80
Sine wave, ac-coupled
Input clock amplitude
differential (VCLKP –
VCLKM)
(1)
(2)
0.2
MSPS
125
1.5
LVPECL, ac-coupled
1.6
LVDS, ac-coupled
0.7
LVCMOS, single-ended, ac-coupled
1.8
VPP
V
With 0dB gain. See the Gain section in the Application Information for relation between input voltage range and gain.
See Application Information.
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Recommended Operating Conditions (continued)
Over operating free-air temperature range, unless otherwise noted.
Input clock duty cycle
MIN
NOM
MAX
Low-speed enabled
40%
50%
60%
Low-speed disabled
35%
50%
65%
UNIT
DIGITAL OUTPUTS
CLOAD
Maximum external load capacitance from each output pin to DRGND
RLOAD
Differential load resistance between the LVDS output pairs (LVDS mode)
TA
Operating free-air temperature
5
pF
Ω
100
–40
85
°C
HIGH PERFORMANCE MODES (3) (4) (5)
Mode 1
Set the MODE 1 register bits to get best performance across sample clock and
input signal frequencies.
Register address = 03h, register data = 03h
Mode 2
Set the MODE 2 register bit to get best performance at high input signal
frequencies greater than 230 MHz.
Register address = 4Ah, register data = 01h
(3)
(4)
(5)
It is recommended to use these modes to obtain best performance. These modes can be set using the serial interface only.
See the Serial Interface section for details on register programming.
Note that these modes cannot be set when the serial interface is not used (when the RESET pin is tied high); see the Device
Configuration section.
7.4 Thermal Information
ADS412x
ADS414x
THERMAL METRIC (1)
UNIT
RGZ (VQFN)
48 PIN
RθJA
Junction-to-ambient thermal resistance
29
°C/W
RθJCtop
Junction-to-case (top) thermal resistance
N/A
°C/W
RθJB
Junction-to-board thermal resistance
10
°C/W
ψJT
Junction-to-top characterization parameter
0.3
°C/W
ψJB
Junction-to-board characterization parameter
9
°C/W
RθJCbot
Junction-to-case (bottom) thermal resistance
1.1
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
7.5 Electrical Characteristics: ADS412x
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1dBFS differential analog input, 0dB gain,
and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature range: TMIN
= –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
Resolution
12
fIN = 10 MHz
fIN = 70 MHz
SNR (signal-to-noise ratio), LVDS
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
8
MAX
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ADS4122 (65MSPS)
71.1
ADS4125 (125MSPS)
71
ADS4122 (65MSPS)
70.9
ADS4125 (125MSPS)
70.8
ADS4122 (65MSPS)
70.7
ADS4125 (125MSPS)
70.6
ADS4122 (65MSPS)
67
70.2
ADS4125 (125MSPS)
68
70.1
ADS4122 (65MSPS)
68.8
ADS4125 (125MSPS)
69.6
UNIT
Bits
dBFS
dBFS
dBFS
dBFS
dBFS
Copyright © 2011–2016, Texas Instruments Incorporated
Product Folder Links: ADS4122 ADS4125 ADS4142 ADS4145
ADS4122, ADS4125, ADS4142, ADS4145
www.ti.com
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Electrical Characteristics: ADS412x (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1dBFS differential analog input, 0dB gain,
and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature range: TMIN
= –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
fIN = 10 MHz
fIN = 70 MHz
SINAD (signal-to-noise and
distortion ratio), LVDS
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
MIN
70.8
ADS4125 (125MSPS)
70.7
ADS4122 (65MSPS)
70.8
ADS4125 (125MSPS)
70.7
ADS4122 (65MSPS)
70.6
ADS4125 (125MSPS)
70.3
ADS4122 (65MSPS)
66
70.1
ADS4125 (125MSPS)
67
69.8
ADS4122 (65MSPS)
68
ADS4125 (125MSPS)
69
ADS4122 (65MSPS)
Spurious-free dynamic range
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
THD
Total harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
86
86
ADS4122 (65MSPS)
87
ADS4125 (125MSPS)
82
ADS4122 (65MSPS)
70
85
ADS4125 (125MSPS)
71
81
ADS4122 (65MSPS)
72.5
ADS4125 (125MSPS)
77
ADS4122 (65MSPS)
82.5
ADS4125 (125MSPS)
82
ADS4122 (65MSPS)
84
ADS4125 (125MSPS)
83.5
ADS4122 (65MSPS)
84
ADS4125 (125MSPS)
80.5
ADS4122 (65MSPS)
69.5
81
ADS4125 (125MSPS)
69.5
79.5
ADS4122 (65MSPS)
72
ADS4125 (125MSPS)
75.5
fIN = 10 MHz
fIN = 70 MHz
HD2
Second-harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
HD3
Third-harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
Copyright © 2011–2016, Texas Instruments Incorporated
MAX
86.5
ADS4125 (125MSPS)
fIN = 70 MHz
SFDR
TYP
ADS4122 (65MSPS)
87
ADS4122 (65MSPS)
88
ADS4125 (125MSPS)
86
ADS4122 (65MSPS)
88
ADS4125 (125MSPS)
82
ADS4122 (65MSPS)
70
86
ADS4125 (125MSPS)
71
83
ADS4122 (65MSPS)
72.5
ADS4125 (125MSPS)
77
ADS4122 (65MSPS)
86.5
ADS4125 (125MSPS)
86
ADS4122 (65MSPS)
86
ADS4125 (125MSPS)
88
ADS4122 (65MSPS)
87
ADS4125 (125MSPS)
85
ADS4122 (65MSPS)
70
85
ADS4125 (125MSPS)
71
81
ADS4122 (65MSPS)
85
ADS4125 (125MSPS)
82
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UNIT
dBFS
dBFS
dBFS
dBFS
dBFS
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
9
ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
www.ti.com
Electrical Characteristics: ADS412x (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1dBFS differential analog input, 0dB gain,
and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature range: TMIN
= –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
fIN = 10 MHz
fIN = 70 MHz
Worst spur
(other than second and third
harmonics)
fIN = 100 MHz
fIN = 170 MHz
MIN
TYP
ADS4122 (65MSPS)
96
ADS4125 (125MSPS)
95
ADS4122 (65MSPS)
96
ADS4125 (125MSPS)
95
ADS4122 (65MSPS)
94
ADS4125 (125MSPS)
95
ADS4122 (65MSPS)
76.5
92
ADS4125 (125MSPS)
76.5
91
fIN = 300 MHz
MAX
dBc
dBc
dBc
dBc
88
ADS4122 (65MSPS)
UNIT
dBc
90
Two-tone intermodulation
distortion
f1 = 100 MHz, f2 = 105 MHz,
each tone at –7 dBFS
Input overload recovery
Recovery to within 1% (of final value) for 6dB overload with
sine-wave input
PSRR
AC power-supply rejection ratio
For 100-mVPP signal on AVDD supply, up to 10 MHz
> 30
dB
ENOB
Effective number of bits
fIN = 170 MHz
11.2
LSBs
DNL
Differential nonlinearity
fIN = 170 MHz
IMD
INL
Integrated nonlinearity
fIN = 170 MHz
ADS4125 (125MSPS)
dBFS
87.5
Clock
cycles
1
±0.2
1.5
ADS4122 (65MSPS)
–0.85
±0.3
3.5
ADS4125 (125MSPS)
±0.35
3.5
LSBs
LSBs
7.6 Electrical Characteristics: ADS414x
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB
gain, and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
Resolution
14
fIN = 10 MHz
fIN = 70 MHz
SNR (signal-to-noise ratio), LVDS
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
SINAD (signal-to-noise and
distortion ratio), LVDS
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
10
MAX
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ADS4142 (65 MSPS)
73.9
ADS4145 (125 MSPS)
73.7
ADS4142 (65 MSPS)
73.5
ADS4145 (125 MSPS)
73.4
ADS4142 (65 MSPS)
73.2
ADS4145 (125 MSPS)
73.1
ADS4142 (65 MSPS)
69
72.4
ADS4145 (125 MSPS)
70
72.2
ADS4142 (65 MSPS)
70.5
ADS4145 (125 MSPS)
71.3
ADS4142 (65 MSPS)
73.5
ADS4145 (125 MSPS)
73.2
ADS4142 (65 MSPS)
73.3
ADS4145 (125 MSPS)
73
ADS4142 (65 MSPS)
73
ADS4145 (125 MSPS)
72.6
ADS4142 (65 MSPS)
68
72.3
ADS4145 (125 MSPS)
69
71.8
ADS4142 (65 MSPS)
69.2
ADS4145 (125 MSPS)
70.6
UNIT
Bits
dBFS
dBFS
dBFS
dBFS
dBFS
dBFS
dBFS
dBFS
dBFS
dBFS
Copyright © 2011–2016, Texas Instruments Incorporated
Product Folder Links: ADS4122 ADS4125 ADS4142 ADS4145
ADS4122, ADS4125, ADS4142, ADS4145
www.ti.com
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Electrical Characteristics: ADS414x (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB
gain, and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
fIN = 10 MHz
fIN = 70 MHz
SFDR
Spurious-free dynamic range
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
THD
Total harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
HD2
Second-harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
fIN = 10 MHz
fIN = 70 MHz
HD3
Third-harmonic distortion
fIN = 100 MHz
fIN = 170 MHz
fIN = 300 MHz
Copyright © 2011–2016, Texas Instruments Incorporated
MIN
TYP
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
86
ADS4142 (65 MSPS)
86.5
ADS4145 (125 MSPS)
85.5
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
82
ADS4142 (65 MSPS)
ADS4145 (125 MSPS)
71
85
72.5
81.5
ADS4142 (65 MSPS)
MAX
72.5
ADS4145 (125 MSPS)
77
ADS4142 (65 MSPS)
84
ADS4145 (125 MSPS)
83
ADS4142 (65 MSPS)
84
ADS4145 (125 MSPS)
83.5
ADS4142 (65 MSPS)
84
ADS4145 (125 MSPS)
81
ADS4142 (65 MSPS)
69.5
82.5
ADS4145 (125 MSPS)
70.5
80
ADS4142 (65 MSPS)
72.5
ADS4145 (125 MSPS)
75.5
ADS4142 (65 MSPS)
88
ADS4145 (125 MSPS)
87
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
85.5
ADS4142 (65 MSPS)
88
ADS4145 (125 MSPS)
82
ADS4142 (65 MSPS)
ADS4145 (125 MSPS)
71
87
72.5
84
ADS4142 (65 MSPS)
72.5
ADS4145 (125 MSPS)
77
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
86
ADS4142 (65 MSPS)
86.5
ADS4145 (125 MSPS)
87
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
85
ADS4142 (65 MSPS)
ADS4145 (125 MSPS)
71
85
72.5
81.5
ADS4142 (65 MSPS)
85
ADS4145 (125 MSPS)
84
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UNIT
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
dBc
11
ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
www.ti.com
Electrical Characteristics: ADS414x (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB
gain, and DDR LVDS interface, unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
fIN = 10 MHz
MIN
96
ADS4145 (125 MSPS)
95
fIN = 70 MHz
Worst spur
(other than second and third
harmonics)
fIN = 100 MHz
fIN = 300 MHz
PSRR
ADS4142 (65 MSPS)
94
ADS4145 (125 MSPS)
95
ADS4142 (65 MSPS)
77.5
92
ADS4145 (125 MSPS)
78.5
91
ADS4142 (65 MSPS)
87
ADS4145 (125 MSPS)
88
ADS4142 (65 MSPS)
88.5
ADS4145 (125 MSPS)
87.5
Two-tone intermodulation
distortion
f1 = 100 MHz, f2 = 105 MHz,
each tone at –7 dBFS
Input overload recovery
Recovery to within 1% (of final value) for 6-dB overload with
sine-wave input
AC power-supply rejection ratio
For 100-mVPP signal on AVDD supply, up to 10 MHz
ENOB
Effective number of bits
fIN = 170 MHz
DNL
Differential nonlinearity
fIN = 170 MHz
INL
Integrated nonlinearity
fIN = 170 MHz
MAX
dBc
dBc
dBc
dBc
dBFS
Clock
cycles
1
> 30
ADS4142 (65 MSPS)
11.5
ADS4145 (125 MSPS)
11.3
–0.95
UNIT
dBc
95
fIN = 170 MHz
IMD
TYP
ADS4142 (65 MSPS)
dB
LSBs
±0.5
1.7
LSBs
±1.5
±4.5
LSBs
7.7 Electrical Characteristics: General
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, and 0-dB gain, unless otherwise noted.
Minimum and maximum values are across the full temperature range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and
DRVDD = 1.8 V.
PARAMETER
MIN
TYP
MAX
UNIT
ANALOG INPUTS
Differential input voltage range
Differential input resistance (at DC); see Figure 106
Differential input capacitance; see Figure 107
VPP
MΩ
4
Analog input bandwidth
Analog input common-mode current (per input pin)
VCM
2
>1
Common-mode output voltage
pF
550
MHz
0.6
µA/MSPS
0.95
VCM output current capability
V
4
mA
DC ACCURACY
Offset error
–15
Temperature coefficient of offset error
2.5
15
0.003
EGREF
Gain error as a result of internal reference inaccuracy alone
EGCHAN
Gain error of channel alone
–2
Temperature coefficient of EGCHAN
mV
mV/°C
2
%FS
–0.2
%FS
0.001
Δ%/°C
POWER SUPPLY
IAVDD
Analog supply current
(1)
IDRVDD
Output buffer supply current
LVDS interface with 100-Ω external
termination
Low LVDS swing (200 mV)
(1)
12
ADS4122/ADS4142 (65MSPS)
42
55
ADS4125/ADS4145 (125MSPS)
62
75
ADS4122/ADS4142 (65MSPS)
28.5
ADS4125/ADS4145 (125MSPS)
35.5
mA
mA
The maximum DRVDD current with CMOS interface depends on the actual load capacitance on the digital output lines. Note that the
maximum recommended load capacitance on each digital output line is 10 pF.
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www.ti.com
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Electrical Characteristics: General (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, 50% clock duty cycle, and 0-dB gain, unless otherwise noted.
Minimum and maximum values are across the full temperature range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and
DRVDD = 1.8 V.
PARAMETER
TYP
MAX
IDRVDD
Output buffer supply current
LVDS interface with 100-Ω external
termination
Standard LVDS swing (350 mV)
ADS4122/ADS4142 (65MSPS)
MIN
40
53
ADS4125/ADS4145 (125MSPS)
48
57
IDRVDD output buffer supply current (1) (2)
CMOS interface (2)
8-pF external load capacitance
fIN = 2.5 MHz
ADS4122/ADS4142 (65MSPS)
15
ADS4125/ADS4145 (125MSPS)
23
Analog power
ADS4122/ADS4142 (65MSPS)
76
ADS4125/ADS4145 (125MSPS)
112
Digital power, LVDS interface, low LVDS
swing
ADS4122/ADS4142 (65MSPS)
Digital power
CMOS interface (2)
8-pF external load capacitance
fIN = 2.5 MHz
ADS4122/ADS4142 (65MSPS)
(2)
mA
mA
mW
52
ADS4125/ADS4145 (125MSPS)
mW
66.5
27
ADS4125/ADS4145 (125MSPS)
41.5
ADS4122/ADS4142 (65MSPS)
105
ADS4125/ADS4145 (125MSPS)
130
Global power-down
10
Standby
UNIT
mW
15
mW
mW
In CMOS mode, the DRVDD current scales with the sampling frequency, the load capacitance on output pins, input frequency, and the
supply voltage (see the CMOS Interface Power Dissipation section in the Application Information).
7.8 Digital Characteristics
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, and 50% clock duty cycle for the ADS4122, ADS4125, ADS4142,
and ADS4145, unless otherwise noted. Minimum and maximum values are across the full temperature range: TMIN = –40°C to
TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.8 V.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
RESET, SCLK, SDATA, and SEN
support 1.8-V and 3.3-V CMOS
logic levels
1.3
OE only supports 1.8-V CMOS
logic levels
1.3
Low-level input voltage
High-level input current: SDATA, SCLK (1)
VHIGH = 1.8 V
10
µA
High-level input current: SEN
VHIGH = 1.8 V
0
µA
Low-level input current: SDATA, SCLK
VLOW = 0 V
0
µA
Low-level input current: SEN
VLOW = 0 V
–10
µA
DIGITAL INPUTS (RESET, SCLK, SDATA, SEN, OE)
High-level input voltage
Low-level input voltage
High-level input voltage
V
0.4
V
V
0.4
V
DIGITAL OUTPUTS (CMOS INTERFACE: D0 TO D13, OVR_SDOUT)
High-level output voltage
DRVDD – 0.1
DRVDD
Low-level output voltage
0
V
0.1
V
DIGITAL OUTPUTS (LVDS INTERFACE: DA0P/M TO DA13P/M, DB0P/M TO DB13P/M, CLKOUTP/M)
High-level output voltage (2)
VODH
Standard swing LVDS
270
350
430
mV
Low-level output voltage (2)
VODL
Standard swing LVDS
–430
–350
–270
mV
High-level output voltage (2)
VODH
Low swing LVDS
200
Low-level output voltage (2)
VODL
Low swing LVDS
–200
Output common-mode voltage
VOCM
(1)
(2)
0.85
1.05
mV
mV
1.25
V
SDATA and SCLK have an internal 180-kΩ pull-down resistor.
With an external 100-Ω termination.
Copyright © 2011–2016, Texas Instruments Incorporated
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13
ADS4122, ADS4125, ADS4142, ADS4145
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
www.ti.com
7.9 Timing Requirements: LVDS and CMOS Modes (1)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, sampling frequency = 125 MSPS, sine wave input clock,
CLOAD = 5 pF (2), and RLOAD = 100 Ω (3), unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.7 V to 1.9 V.
PARAMETER
tA
TEST CONDITIONS
Aperture delay
Variation of aperture
delay
tJ
MIN
TYP
MAX
0.6
0.8
1.2
Between two devices at the same temperature and
DRVDD supply
Aperture jitter
Wakeup time
ADC latency (4)
Time to valid data after coming out of STANDBY
mode
Time to valid data after coming out of PDN GLOBAL
mode
UNIT
ns
±100
ps
100
fS rms
5
25
µs
100
500
µs
Low-latency mode (default after reset)
10
Clock
cycles
Low-latency mode disabled (gain enabled, offset
correction disabled)
16
Clock
cycles
Low-latency mode disabled (gain and offset
correction enabled)
17
Clock
cycles
2.3
3
ns
0.35
0.6
ns
3
4.2
DDR LVDS MODE (5) (6)
tSU
Data setup time (3)
Data valid (7) to zero-crossing of CLKOUTP
tH
Data hold time (3)
Zero-crossing of CLKOUTP to data becoming
invalid (7)
tPDI
Clock propagation
delay
Input clock rising edge cross-over to output clock
rising edge cross-over
Sampling frequency ≤ 125 MSPS
Variation of tPDI
Between two devices at the same temperature and
DRVDD supply
±0.6
LVDS bit clock duty
cycle
Duty cycle of differential clock, (CLKOUTP –
CLKOUTM)
Sampling frequency ≤ 125 MSPS
48%
tRISE, tFALL
Data rise time,
Data fall time
Rise time measured from –100mV to 100mV
Fall time measured from 100mV to –100mV
Sampling frequency ≤ 125 MSPS
0.14
ns
tCLKRISE,
tCLKFALL
Output clock rise
time,
Output clock fall time
Rise time measured from –100 mV to 100 mV
Fall time measured from 100 mV to –100 mV
Sampling frequency ≤ 125 MSPS
0.14
ns
tOE
Output enable (OE) to
Time to valid data after OE becomes active
data delay
50
5.4
ns
ns
100
ns
PARALLEL CMOS MODE (8)
Data setup time
Data valid (9) to 50% of CLKOUT rising edge
3.1
3.7
ns
tHOLD
Data hold time
50% of of CLKOUT rising edge to data becoming
invalid (9)
3.2
4
ns
tPDI
Clock propagation
delay
Input clock rising edge cross-over to 50% of output
clock rising edge
Sampling frequency ≤ 125 MSPS
4
5.5
Output clock duty
cycle
Duty cycle of output clock, CLKOUT
Sampling frequency ≤ 125 MSPS
tSETUP
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
14
7
ns
47%
Timing parameters are ensured by design and characterization but are not production tested.
CLOAD is the effective external single-ended load capacitance between each output pin and ground.
RLOAD is the differential load resistance between the LVDS output pair.
At higher frequencies, tPDI is greater than one clock period and overall latency = ADC latency + 1.
Measurements are done with a transmission line of 100-Ω characteristic impedance between the device and the load. Setup and hold
time specifications take into account the effect of jitter on the output data and clock.
The LVDS timings are unchanged for low latency disabled and enabled.
Data valid refers to a logic high of 100 mV and a logic low of –100 mV.
Low latency mode enabled.
Data valid refers to a logic high of 1.25 V and a logic low of 0.54 V.
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Copyright © 2011–2016, Texas Instruments Incorporated
Product Folder Links: ADS4122 ADS4125 ADS4142 ADS4145
ADS4122, ADS4125, ADS4142, ADS4145
www.ti.com
SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Timing Requirements: LVDS and CMOS Modes(1) (continued)
Typical values are at 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, sampling frequency = 125 MSPS, sine wave input clock,
CLOAD = 5 pF(2), and RLOAD = 100 Ω(3), unless otherwise noted. Minimum and maximum values are across the full temperature
range: TMIN = –40°C to TMAX = 85°C, AVDD = 1.8 V, and DRVDD = 1.7 V to 1.9 V.
PARAMETER
TEST CONDITIONS
MIN
tRISE, tFALL
Data rise time,
Data fall time
Rise time measured from 20% to 80% of DRVDD
Fall time measured from 80% to 20% of DRVDD
Sampling frequency ≤ 125 MSPS
tCLKRISE,
tCLKFALL
Output clock rise
time,
Output clock fall time
Rise time measured from 20% to 80% of DRVDD
Fall time measured from 80% to 20% of DRVDD
Sampling frequency ≤ 125 MSPS
tOE
Output enable (OE) to
Time to valid data after OE becomes active
data delay
TYP
MAX
UNIT
0.35
ns
0.35
ns
20
40
ns
7.10 Serial Interface Timing Characteristics
Typical values at 25°C, minimum and maximum values across the full temperature range: TMIN = –40°C to TMAX = 85°C,
AVDD = 1.8 V, and DRVDD = 1.8 V, unless otherwise noted.
PARAMETER
MIN
TYP
> DC
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
SDATA setup time
25
ns
tDH
SDATA hold time
25
ns
7.11 Reset Timing Requirements
Typical values at 25°C and minimum and maximum values across the full temperature range: TMIN = –40°C to TMAX = 85°C,
unless otherwise noted.
PARAMETER
TEST CONDITIONS
MIN
t1
Power-on delay
Delay from power-up of AVDD and DRVDD to RESET
pulse active
t2
Reset pulse width
Pulse width of active RESET signal that resets the
serial registers
t3
(1)
TYP
MAX
1
UNIT
ms
10
ns
1 (1)
Delay from RESET disable to SEN active
100
µs
ns
The reset pulse is needed only when using the serial interface configuration. If the pulse width is greater than 1µs, the device could
enter the parallel configuration mode briefly and then return back to serial interface mode.
7.12 Timing Characteristics at Lower Sampling Frequencies
SAMPLING
FREQUENCY (MSPS)
tsu, SETUP TIME (ns)
MIN
TYP
65
5.5
80
4.5
tPDI, CLOCK PROPAGATION DELAY
(ns)
th, HOLD TIME (ns)
MAX
MIN
TYP
6.5
0.35
0.6
5.2
0.35
0.6
MAX
MIN
TYP
MAX
DDR LVDS
CMOS (LOW LATENCY ENABLED)
(1)
65
6.5
7.5
6.5
7.5
4
5.5
7
80
5.4
6
5.4
6
4
5.5
7
CMOS (LOW LATENCY DISABLED)
(1)
(1)
65
6
7
7
8
4
5.5
7
80
4.8
5.5
5.7
6.5
4
5.5
7
125
2.5
3.2
3.5
4.3
4
5.5
7
Timing specified with respect to output clock
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Dn_Dn + 1_P
Logic 0
VODL
Logic 1
VODH
Dn_Dn + 1_M
VOCM
GND
(1) With external 100-Ω termination.
Figure 1. LVDS Output Voltage Levels
N+3
N+2
N+1
Sample N
N+4
N + 12
N + 11
N + 10
Input Signal
tA
CLKP
Input Clock
CLKM
CLKOUTM
CLKOUTP
tPDI
tH
10 Clock Cycles
DDR LVDS
(1)
tSU
(2)
Output Data
(DXP, DXM)
E
O
N - 10
E
O
N-9
E
O
N-8
E
O
O
E
N-7
E
O
O
E
N-6
E
O
N+1
N
E
O
E
O
N+2
tPDI
CLKOUT
tSU
Parallel CMOS
10 Clock Cycles
Output Data
N - 10
N-9
N-8
(1)
N-7
tH
N-1
N
N+1
(1) ADC latency in low-latency mode. At higher sampling frequencies, tDPI is greater than one clock cycle which then makes the overall
latency = ADC latency + 1.
(2) E = Even bits (D0, D2, D4, etc). O = Odd bits (D1, D3, D5, and so forth).
Figure 2. Latency Diagram
16
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CLKM
Input
Clock
CLKP
tPDI
CLKOUTP
Output
Clock
CLKOUTM
tSU
Output Dn_Dn + 1_P
Data Pair Dn_Dn + 1_M
tSU
tH
Dn
(1)
tH
Dn + 1
(1)
(1) Dn = bits D0, D2, D4, etc. Dn + 1 = Bits D1, D3, D5, and so forth.
Figure 3. LVDS Mode Timing
CLKM
Input
Clock
CLKP
tPDI
Output
Clock
CLKOUT
tSU
Output
Data
tH
Dn
Dn
(1)
CLKM
Input
Clock
CLKP
tSTART
tDV
Output
Data
Dn
Dn
(1)
Dn = bits D0, D1, D2, and so forth.
Figure 4. CMOS Mode Timing
Register Address
SDATA
A7
A6
A5
A3
A4
Register Data
A2
A1
A0
D7
D6
D5
tSCLK
D4
tDSU
D3
D2
D1
D0
tDH
SCLK
tSLOADS
tSLOADH
SEN
RESET
Figure 5. Serial Interface Timing
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Power Supply
AVDD, DRVDD
t1
RESET
t3
t2
SEN
A high pulse on the RESET pin is required in the serial interface mode in case of initialization through hardware reset. For parallel interface
operation, RESET must be permanently tied high.
Figure 6. Reset Timing Diagram
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7.13 Typical Characteristics
7.13.1 Typical Characteristics: ADS4122
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
0
0
SFDR = 85.1dBc
SNR = 71.3dBFS
SINAD = 71.1dBFS
THD = 83dBc
−20
−20
−40
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
−100
0
5
10
15
20
25
−120
30 32.5
15
20
25
30 32.5
Figure 8. FFT for 170-MHz Input Signal
0
SFDR = 71.9dBc
SNR = 69.3dBFS
SINAD = 67.7dBFS
THD = 71.7dBc
Each Tone at
−7dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 90.1dBFS
SFDR = 97.3dBFS
−20
−40
Amplitude (dB)
Amplitude (dB)
10
Figure 7. FFT for 20-MHz Input Signal
−40
−60
−60
−80
−80
−100
−100
0
5
10
15
20
25
−120
30 32.5
0
5
10
15
20
25
30 32.5
Frequency (MHz)
Frequency (MHz)
Figure 9. FFT for 300-MHz Input Signal
Figure 10. FFT for Two-Tone Input Signal
0
88
Each Tone at
−36dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 99.5dBFS
SFDR = 106.9dBFS
−20
83
78
SFDR (dBc)
−40
−60
73
−80
68
−100
63
−120
5
Frequency (MHz)
−20
−120
0
Frequency (MHz)
0
Amplitude (dB)
−60
−80
−120
SFDR = 84.3dBc
SNR = 70.5dBFS
SINAD = 70.3dBFS
THD = 82.7dBc
0
5
10
15
20
25
30 32.5
58
0
50
100
150
200
250
300
350
400
Frequency (MHz)
Input Frequency (MHz)
Figure 11. FFT for Two-Tone Input Signal
Figure 12. SFDR vs Input Frequency
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Typical Characteristics: ADS4122 (continued)
71.5
98
High Perf MODE1 Enabled
Default
170MHz
220MHz
94
71
300MHz
400MHz
90
70.5
86
82
SFDR (dBc)
SNR (dBFS)
70
69.5
78
74
69
70
68.5
66
68
0
50
100
150
200
250
300
350
58
400
0
0.5
1
1.5
2
2.5
3
3.5
4.5
5
5.5
6
Gain (dB)
Figure 13. SNR vs Input Frequency
Figure 14. SFDR Across Gain and Input Frequency
72
74
120
170MHz
220MHz
71
300MHz
400MHz
Input Frequency = 40MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
70
73.5
73
100
69
SFDR (dBc, dBFS)
68
67
SINAD (dBFS)
4
Input Frequency (MHz)
66
65
64
63
62
90
72.5
80
72
70
71.5
60
71
50
70.5
40
70
30
69.5
SNR (dBFS)
67.5
62
61
60
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
20
−45
6
−40
−35
Gain (dB)
SFDR (dBFS)
SFDR (dBc)
SNR
70
71.5
60
71
50
70.5
40
70
30
69.5
−25
−20
−15
−10
−5
0
69
Amplitude (dBFS)
Figure 17. Performance Across Input Amplitude (Single
Tone)
20
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SFDR (dBc)
72
SNR (dBFS)
SFDR (dBc, dBFS)
72.5
80
−30
−5
0
69
71.5
Input Frequency = 150MHz
90
−35
−10
94
73
−40
−15
SFDR
SNR
73.5
100
20
−45
−20
Figure 16. Performance Across Input Amplitude (Single
Tone)
74
120
Input Frequency = 150MHz
−25
Amplitude (dBFS)
Figure 15. SINAD Across Gain and Input Frequency
110
−30
90
71
86
70.5
82
70
78
69.5
74
0.8
0.85
0.9
0.95
1
1.05
SNR (dBFS)
59
69
1.1
Input Common−Mode Voltage (V)
Figure 18. Performance vs Input Common-Mode Voltage
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Typical Characteristics: ADS4122 (continued)
73
100
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
96
92
1.85
1.9
1.95
Input Frequency = 150MHz
72
88
1.85
1.9
1.95
71
SNR (dBFS)
84
SFDR (dBc)
1.65
1.7
1.75
1.8
80
76
70
69
72
68
68
64
60
−40
−15
10
35
60
10
35
60
85
Temperature (°C)
Figure 19. SFDR Across Temperature vs AVDD Supply
Figure 20. SNR Across Temperature vs AVDD Supply
Input Frequency = 40MHz
71
70.5
SFDR (dBc)
90
SNR (dBFS)
71.5
70
86
69.5
84
1.7
1.75
1.8
1.85
1.9
69
1.95
87
71
86
70
85
69
84
68
83
67
82
66
81
65
80
64
79
0
DRVDD Supply (V)
93
71
69
87
67
85
65
83
63
81
61
79
59
77
57
2
2.5
3
63
3.5
2.5
3
55
3.5
Differential Clock Amplitude (VPP)
Figure 23. Performance Across Input Clock Amplitude
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72
THD
SNR
73
89
1.5
2
Input Frequency = 10MHz
91
1
1.5
94
THD (dBc)
SFDR
SNR
SNR (dBFS)
Input Frequency = 150MHz
0.5
1
Figure 22. Performance Across Input Clock Amplitude
75
95
0
0.5
Differential Clock Amplitude (VPP)
Figure 21. Performance Across DRVDD Supply Voltage
75
72
90
71.5
86
71
82
70.5
78
40
45
50
55
60
SNR (dBFS)
82
1.65
SFDR
SNR
88
92
88
73
89
SNR
SFDR
SNR (dBFS)
72
Input Frequency =150MHz
SFDR (dBc)
−15
Temperature (°C)
94
SFDR (dBc)
67
−40
85
70
Input Clock Duty Cycle (%)
Figure 24. Performance Across Input Clock Duty Cycle
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7.13.2 Typical Characteristics: ADS4125
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
0
0
SFDR = 86.9dBc
SNR = 71.2dBFS
SINAD = 71dBFS
THD = 83.9dBc
−20
−20
−40
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
−100
0
10
20
30
40
50
−120
60
30
40
50
60
Figure 26. FFT for 170-MHz Input Signal
0
SFDR = 79.7dBc
SNR = 70dBFS
SINAD = 69.5dBFS
THD = 78.3dBc
Each Tone at
−7dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 87.7dBFS
SFDR = 96.7dBFS
−20
−40
Amplitude (dB)
Amplitude (dB)
20
Figure 25. FFT for 20-MHz Input Signal
−40
−60
−60
−80
−80
−100
−100
0
10
20
30
40
50
−120
60
0
10
20
30
40
50
60
Frequency (MHz)
Frequency (MHz)
Figure 27. FFT for 300-MHz Input Signal
Figure 28. FFT for Two-Tone Input Signal
0
90
Each Tone at
−36dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 99.4dBFS
SFDR = 106.3dBFS
−20
85
80
SFDR (dBc)
−40
Amplitude (dB)
10
Frequency (MHz)
−20
−120
0
Frequency (MHz)
0
−60
75
−80
70
−100
65
−120
22
−60
−80
−120
SFDR = 82.4dBc
SNR = 70.5dBFS
SINAD = 70.1dBFS
THD = 80.5dBc
0
10
20
30
40
50
60
60
0
50
100
150
200
250
300
350
400
Frequency (MHz)
Input Frequency (MHz)
Figure 29. FFT for Two-Tone Input Signal
Figure 30. SFDR vs Input Frequency
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Typical Characteristics: ADS4125 (continued)
71.5
96
High Perf MODE1 Enabled
Default
170MHz
220MHz
300MHz
400MHz
92
71
88
70.5
SFDR (dBc)
SNR (dBFS)
84
70
80
76
69.5
72
69
68
68.5
0
50
100
150
200
250
300
350
64
400
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
Input Frequency (MHz)
Gain (dB)
Figure 31. SNR vs Input Frequency
Figure 32. SFDR Across Gain and Input Frequency
72
74
120
170MHz
220MHz
71
300MHz
400MHz
Input Frequency = 40MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
73.5
73
100
SFDR (dBc, dBFS)
SINAD (dBFS)
69
68
67
66
90
72.5
80
72
70
71.5
60
71
50
70.5
40
70
30
69.5
20
69
SNR (dBFS)
70
65
64
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
10
−45
6
−40
−35
Gain (dB)
SFDR (dBFS)
SFDR (dBc)
SNR
70
71.5
60
71
50
70.5
40
70
30
69.5
−25
−20
−15
−10
−5
0
69
Amplitude (dBFS)
Figure 35. Performance Across Input Amplitude (Single
Tone)
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SFDR (dBc)
72
SNR (dBFS)
SFDR (dBc, dBFS)
72.5
80
−30
−5
0
68.5
71
Input Frequency = 150MHz
90
−35
−10
90
73
−40
−15
SFDR
SNR
73.5
100
20
−45
−20
Figure 34. Performance Across Input Amplitude (Single
Tone)
74
120
Input Frequency = 150MHz
−25
Amplitude (dBFS)
Figure 33. SINAD Across Gain and Input Frequency
110
−30
86
70.5
82
70
78
69.5
74
69
70
0.8
0.85
0.9
0.95
1
1.05
SNR (dBFS)
63
68.5
1.1
Input Common−Mode Voltage (V)
Figure 36. Performance vs Input Common-Mode Voltage
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Typical Characteristics: ADS4125 (continued)
73
100
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
96
92
1.85
1.9
1.95
Input Frequency = 150MHz
72
88
1.85
1.9
1.95
71
SNR (dBFS)
84
SFDR (dBc)
1.65
1.7
1.75
1.8
80
76
70
69
72
68
68
64
60
−40
−15
10
35
60
−15
35
60
85
Temperature (°C)
Figure 37. SFDR Across Temperature vs AVDD Supply
Figure 38. SNR Across Temperature vs AVDD Supply
Input Frequency = 40MHz
71
70.5
82
SFDR (dBc)
84
SNR (dBFS)
71.5
70
80
69.5
78
1.7
1.75
1.8
1.85
69
1.95
1.9
SFDR
SNR
88
86
76
1.65
74
89
SNR
SFDR
73
87
72
86
71
85
70
84
69
83
68
82
67
81
66
80
65
79
0
0.5
1
DRVDD Supply (V)
1.5
2
2.5
SNR (dBFS)
72
Input Frequency =150MHz
64
3.5
3
Differential Clock Amplitude (VPP)
Figure 39. Performance Across DRVDD Supply Voltage
Figure 40. Performance Across Input Clock Amplitude
73
73
72
72
91
71
71
89
70
87
69
85
68
83
67
81
66
79
65
77
64
65
75
63
64
62
63
SFDR
SNR
93
Default
Low−Speed Mode Enabled
70
SNR (dBFS)
Input Frequency = 150MHz
SNR (dBFS)
95
SFDR (dBc)
10
Temperature (°C)
88
SFDR (dBc)
67
−40
85
69
68
67
66
Input Frequency = 10MHz
73
0
0.5
1
1.5
2
2.5
3
3.5
4
Differential Clock Amplitude (VPP)
Figure 41. Performance Across Input Clock Amplitude
24
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30
35
40
45
50
55
60
65
70
Input Clock Duty Cycle (%)
Figure 42. SNR Across Input Clock Duty Cycle
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7.13.3 Typical Characteristics: ADS4142
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
0
0
SFDR = 83.4dBc
SNR = 74.3dBFS
SINAD = 73.7dBFS
THD = 82dBc
−20
−20
−40
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
−100
0
5
10
15
20
25
−120
30 32.5
5
10
15
20
25
30 32.5
Frequency (MHz)
Figure 43. FFT for 20-MHz Input Signal
Figure 44. FFT for 170-MHz Input Signal
0
SFDR = 70.7dBc
SNR = 68.4dBFS
SINAD = 66.3dBFS
THD = 69.3dBc
−20
Each Tone at
−7dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 88.7dBFS
SFDR = 96.6dBFS
−20
−40
Amplitude (dB)
−40
−60
−60
−80
−80
−100
−100
−120
0
Frequency (MHz)
0
Amplitude (dB)
−60
−80
−120
SFDR = 83dBc
SNR = 72.8dBFS
SINAD = 72.4dBFS
THD = 81.6dBc
0
5
10
15
20
25
−120
30 32.5
0
5
10
15
20
25
30 32.5
Frequency (MHz)
Frequency (MHz)
Figure 45. FFT for 300-MHz Input Signal
Figure 46. FFT for Two-Tone Input Signal
0
93
Each Tone at
−36dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 99dBFS
SFDR = 105.3dBFS
−20
88
83
SFDR (dBc)
Amplitude (dB)
−40
−60
78
73
−80
68
−100
−120
63
0
5
10
15
20
25
30 32.5
58
0
50
100
150
200
250
300
350
400
Frequency (MHz)
Input Frequency (MHz)
Figure 47. FFT for Two-Tone Input Signal
Figure 48. SFDR vs Input Frequency
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Typical Characteristics: ADS4142 (continued)
74
98
High Perf MODE1 Enabled
Default
73
90
72.5
86
72
82
71.5
71
74
70
70
66
69.5
62
0
50
100
150
200
250
300
350
58
400
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
Input Frequency (MHz)
Gain (dB)
Figure 49. SNR vs Input Frequency
Figure 50. SFDR Across Gain and Input Frequency
77
120
170MHz
220MHz
72
300MHz
400MHz
Input Frequency = 40MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
71
76.5
76
70
100
69
90
75.5
80
75
70
74.5
60
74
63
50
73.5
62
40
73
30
72.5
SFDR (dBc, dBFS)
68
67
66
65
64
SNR (dBFS)
73
SINAD (dBFS)
300MHz
400MHz
78
70.5
69
170MHz
220MHz
94
SFDR (dBc)
SNR (dBFS)
73.5
61
60
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
20
−70
6
−60
Gain (dB)
Input Frequency = 150MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
70
74.5
60
74
50
73.5
40
73
30
72.5
−20
−10
0
72
Amplitude (dBFS)
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SFDR (dBc)
75
SNR (dBFS)
SFDR (dBc, dBFS)
75.5
80
Figure 53. Performance Across Input Amplitude (Single
Tone)
26
0
72
74
Input Frequency = 150MHz
90
−30
−10
90
76
−40
−20
SFDR
SNR
76.5
100
−50
−30
Figure 52. Performance Across Input Amplitude (Single
Tone)
77
120
−60
−40
Amplitude (dBFS)
Figure 51. SINAD Across Gain and Input Frequency
20
−70
−50
86
73.5
82
73
78
72.5
74
72
70
0.8
0.85
0.9
0.95
1
1.05
SNR (dBFS)
59
71.5
1.1
Input Common−Mode Voltage (V)
Figure 54. Performance vs Input Common-Mode Voltage
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Typical Characteristics: ADS4142 (continued)
75
100
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
96
1.85
1.9
1.95
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
74
1.85
1.9
1.95
92
73
SNR (dBFS)
SFDR (dBc)
88
84
80
72
76
71
72
70
68
64
−40
−15
10
35
60
10
35
60
85
Temperature (°C)
Figure 55. SFDR Across Temperature vs AVDD Supply
Figure 56. SNR Across Temperature vs AVDD Supply
90
73
88
72.5
86
72
84
71.5
1.75
1.8
1.85
1.9
71
1.95
89
75
88
74
87
73
86
72
85
71
84
70
83
69
82
0
DRVDD Supply (V)
89
85
70
83
68
81
66
79
64
77
62
75
60
2
2.5
3
68
3.5
2.5
3
58
3.5
Differential Clock Amplitude (VPP)
Figure 59. Performance Across Input Clock Amplitude
Copyright © 2011–2016, Texas Instruments Incorporated
74.5
THD
SNR
74
72
1.5
2
Input Frequency = 10MHz
87
1
1.5
94
THD (dBc)
SFDR
SNR
SNR (dBFS)
Input Frequency = 150MHz
0.5
1
Figure 58. Performance Across Input Clock Amplitude
76
91
0
0.5
Differential Clock Amplitude (VPP)
Figure 57. Performance Across DRVDD Supply Voltage
73
SFDR
SNR
90
74
86
73.5
82
73
78
40
45
50
55
60
SNR (dBFS)
1.7
SFDR (dBc)
73.5
SNR (dBFS)
Input Frequency = 40MHz
92
82
1.65
76
90
SNR
SFDR
SNR (dBFS)
74
Input Frequency =150MHz
SFDR (dBc)
−15
Temperature (°C)
94
SFDR (dBc)
69
−40
85
72.5
Input Clock Duty Cycle (%)
Figure 60. Performance Across Input Clock Duty Cycle
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Typical Characteristics: ADS4142 (continued)
50
1.5
45
1
40
Code Occurrence (%)
35
INL (LSB)
0.5
0
−0.5
30
25
20
15
10
−1
5
−1.5
0
2048
4096
0
6144 8192 10240 12288 14336 16384
Output Code (LSB)
Figure 61. Integral Nonlinearity
8168 8169 8170 8171 8172 8173 8174 8175 8176
Output Code (LSB)
Figure 62. Output Noise Histogram (with Inputs Shorted to
VCM)
7.13.4 Typical Characteristics: ADS4145
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
0
0
SFDR = 86dBc
SNR = 74dBFS
SINAD =73.7dBFS
THD = 83.5dBc
−20
−20
28
−40
Amplitude (dB)
Amplitude (dB)
−40
−60
−60
−80
−80
−100
−100
−120
SFDR = 82.5dBc
SNR = 72.8dBFS
SINAD = 72.2dBFS
THD = 80.1dBc
0
10
20
30
40
50
60
−120
0
10
20
30
40
50
60
Frequency (MHz)
Frequency (MHz)
Figure 63. FFT for 20-MHz Input Signal
Figure 64. FFT for 170-MHz Input Signal
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Typical Characteristics: ADS4145 (continued)
0
0
SFDR = 80dBc
SNR = 72dBFS
SINAD = 71.3dBFS
THD = 78.5dBc
−20
−20
−40
Amplitude (dB)
Amplitude (dB)
−40
−60
−80
−100
−100
0
10
20
30
40
50
−120
60
0
10
20
30
50
60
Frequency (MHz)
Figure 65. FFT for 300-MHz Input Signal
Figure 66. FFT for Two-Tone Input Signal
0
90
Each Tone at
−36dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 99.2dBFS
SFDR = 106.6dBFS
85
80
SFDR (dBc)
−40
−60
75
−80
70
−100
65
−120
0
10
20
30
40
50
60
60
0
50
100
150
200
250
300
350
400
Frequency (MHz)
Input Frequency (MHz)
Figure 67. FFT for Two-Tone Input Signal
Figure 68. SFDR vs Input Frequency
74
96
High Perf MODE1 Enabled
Default
170MHz
220MHz
73.5
92
73
88
72.5
84
SFDR (dBc)
SNR (dBFS)
40
Frequency (MHz)
−20
Amplitude (dB)
−60
−80
−120
Each Tone at
−7dBFS Amplitude
fIN1 = 100MHz
fIN2 = 105MHz
Two−Tone IMD = 87.7dBFS
SFDR = 97.5dBFS
72
80
71.5
76
71
72
70.5
68
70
0
50
100
150
200
250
300
350
400
300MHz
400MHz
64
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
Input Frequency (MHz)
Gain (dB)
Figure 69. SNR vs Input Frequency
Figure 70. SFDR Across Gain and Input Frequency
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Typical Characteristics: ADS4145 (continued)
76.5
120
170MHz
220MHz
73
300MHz
400MHz
Input Frequency = 40MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
72
75.5
100
71
SFDR (dBc, dBFS)
70
SINAD (dBFS)
76
69
68
67
66
65
90
75
80
74.5
70
74
60
73.5
50
73
40
72.5
SNR (dBFS)
74
64
63
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
30
−70
6
−60
−50
Gain (dB)
Input Frequency = 150MHz
SFDR (dBFS)
SFDR (dBc)
SNR
110
74.5
70
74
60
73.5
50
73
40
72.5
30
72
−20
−10
0
SFDR (dBc)
80
SNR (dBFS)
SFDR (dBc, dBFS)
75
71.5
74
86
73.5
82
73
78
72.5
74
72
70
0.8
Amplitude (dBFS)
0.85
0.9
0.95
1
1.05
71.5
1.1
Input Common−Mode Voltage (V)
Figure 73. Performance Across Input Amplitude (Single
Tone)
Figure 74. Performance vs Input Common-Mode Voltage
75
100
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
96
92
1.85
1.9
1.95
Input Frequency = 150MHz
1.65
1.7
1.75
1.8
74
88
1.85
1.9
1.95
73
84
SNR (dBFS)
SFDR (dBc)
72
SFDR
SNR
76
90
−30
0
90
75.5
−40
−10
Input Frequency = 150MHz
100
−50
−20
Figure 72. Performance Across Input Amplitude (Single
Tone)
76.5
120
−60
−30
Amplitude (dBFS)
Figure 71. SINAD Across Gain and Input Frequency
20
−70
−40
SNR (dBFS)
62
80
76
72
71
72
68
70
64
60
−40
30
−15
10
35
60
85
69
−40
−15
10
35
60
85
Temperature (°C)
Temperature (°C)
Figure 75. SFDR Across Temperature vs AVDD Supply
Figure 76. SNR Across Temperature vs AVDD Supply
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SBAS520B – FEBRUARY 2011 – REVISED JANUARY 2016
Typical Characteristics: ADS4145 (continued)
Input Frequency = 40MHz
86
72
84
71.5
82
71
80
70.5
1.75
1.8
1.85
SFDR (dBc)
72.5
1.7
70
1.95
1.9
SFDR
SNR
89
88
78
1.65
76
90
SNR
SFDR
SNR (dBFS)
SFDR (dBc)
Input Frequency =150MHz
75
88
74
87
73
86
72
85
71
84
70
83
69
82
68
81
67
80
0
0.5
1
DRVDD Supply (V)
1.5
2
2.5
3
3.5
4
SNR (dBFS)
73
90
66
Differential Clock Amplitude (VPP)
Figure 77. Performance Across DRVDD Supply Voltage
Figure 78. Performance Across Input Clock Amplitude
76
75
89
74
74
86
72
83
70
80
68
77
66
74
64
71
62
67
60
66
92
Input Frequency = 150MHz
SFDR
SNR
Default
Low−Speed Mode Enabled
73
SNR (dBFS)
SNR (dBFS)
SFDR (dBc)
72
71
70
69
68
Input Frequency = 10MHz
68
0
0.5
1
1.5
2
2.5
3
3.5
4
30
35
40
45
50
55
60
65
70
Input Clock Duty Cycle (%)
Differential Clock Amplitude (VPP)
Figure 79. Performance Across Input Clock Amplitude
Figure 80. SNR Across Input Clock Duty Cycle
35
1.5
30
1
Code Occurrence (%)
25
INL (LSB)
0.5
0
−0.5
20
15
10
−1
−1.5
5
0
2048
4096
6144 8192 10240 12288 14336 16384
Output Code (LSB)
Figure 81. Integral Nonlinearity
Copyright © 2011–2016, Texas Instruments Incorporated
0
8170 8171 8172 8173 8174 8175 8176 8177 8178 8179
Output Code (LSB)
Figure 82. Output Noise Histogram (With Inputs Shorted to
VCM)
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7.13.5 Typical Characteristics: Common
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
0
0
PSRR on AVDD Supply 50mVPP
−10
−10
−20
−20
PSRR (dB)
CMRR (dB)
Input Frequency = 70MHz
50mVPP Signal Superimposed
on Input Common−Mode Voltage (0.95V)
−30
−30
−40
−40
−50
−50
−60
0
50
100
150
200
250
−60
300
10
20
30
40
50
60
70
80
90
Frequency of Signal on Supply (MHz)
Figure 83. CMRR vs Frequency
Figure 84. PSRR vs Frequency
100
70
130
AVDD Power
DRVDD Power 200mV Swing
DRVDD Power 350mV Swing
120
LVDS, 200mV Swing
LVDS, 350mV Swing
CMOS, 6pF Load Capacitance
CMOS, 8pF Load Capacitance
65
60
110
55
100
50
DRVDD Current (mA)
Power (mW)
0
Frequency of Input Common−Mode Signal (MHz)
90
80
70
45
40
35
30
25
60
20
50
15
10
40
30
5
5
25
45
65
85
Sampling Frequency (MSPS)
105
Figure 85. Power vs Sample Rate
32
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125
0
5
25
45
65
85
Sampling Frequency (MSPS)
105
125
Figure 86. DRVDD Current vs Sample Rate
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7.13.6 Typical Characteristics: Contour
At 25°C, AVDD = 1.8 V, DRVDD = 1.8 V, maximum rated sampling frequency, sine wave input clock, 1.5-VPP
differential clock amplitude, 50% clock duty cycle, –1-dBFS differential analog input, 0-dB gain, low-latency
mode, DDR LVDS output interface, and 32k-point FFT, unless otherwise noted.
125
120
125
120
84
75
81
87
67
71
100
63
90
84
80
87
84
87
70
60
81
75
67
71
78
84
63
84
50
87
84
40
75
84
87
84
71
87
90
69
90
80
84
73
70
77
87
60
87
87
69
81
50
73
81
55
77
65
69
84
87
61
20
20
50
100
150
200
250
300
350
400
20
50
100
150
200
Input Frequency (MHz)
60
55
65
250
300
350
400
Input Frequency (MHz)
70
75
80
60
85
65
70
75
SFDR (dBc)
80
85
90
SFDR (dBc)
Figure 87. SFDR Across Input and Sampling Frequencies
(0-dB Gain)
Figure 88. SFDR Across Input and Sampling Frequencies
(6-dB Gain)
125
120
125
120
72.5
73
73.5
110
72
90
80
72
72.5
73
70
73.5
60
71
69
70
50
40
69
72
30
72.5
73.5
69
73
66
20
20
50
100
150
200
250
300
90
80
67
68
70
67.5
66.5
60
50
67
350
66.5
67
68
69
65.5
66
65
20
400
20
50
100
150
200
Input Frequency (MHz)
66
66
66.5
67
67.5
68
30
67
68
67
100
40
68
70
71
67.5
110
70
71
100
Sampling Frequency (MSPS)
Sampling Frequency (MSPS)
73
81
30
59
63
67
20
250
300
350
400
67.5
68
Input Frequency (MHz)
70
71
64
73
72
64.5
65
65.5
66
SNR (dBFS)
66.5
67
SNR (dBFS)
Figure 89. ADS414x: SNR ACROSS Input and Sampling
Frequencies (0-dB Gain)
Figure 90. ADS414x: SNR Across Input and Sampling
Frequencies (6-dB Gain)
125
120
125
120
70.5
71
110
70
110
69.5
100
Sampling Frequency (MSPS)
Sampling Frequency (MSPS)
77
100
87
75
84
87
90
40
78
81
30
87
87
87
110
78
Sampling Frequency (MSPS)
Sampling Frequency (MSPS)
110
84
69
90
80
70
69.5
70.5
71
70
60
68
50
69
40
69.5
30
70.5
70
100
150
71
69
80
67
70
66
66.5
60
50
65.5
66
30
66
67
90
40
67
68
66.5
67
100
20
67
66
66.5
65
65.5
64.5
20
20
50
200
250
300
350
400
20
50
100
150
200
Input Frequency (MHz)
65
66
67
68
250
300
350
64
400
Input Frequency (MHz)
69
70
71
64
64.5
65
SNR (dBFS)
Figure 91. ADS412x SNR Across Input and Sampling
Frequencies (0-dB Gain)
Copyright © 2011–2016, Texas Instruments Incorporated
65.5
66
66.5
67
SNR (dBFS)
Figure 92. ADS412x SNR Across Input and Sampling
Frequencies (6-dB Gain)
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8 Detailed Description
8.1 Overview
The ADS412x and ADS414x devices are high-performance, low-power, 12-bit and 14-bit analog-to-digital
converters (ADC) with maximum sampling rates up to 65/125 MSPS. The conversion process is initiated by a
rising edge of the external input clock when 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 10
clock cycles. The output is available as 12-bit and 14-bit data, in DDR LVDS mode or CMOS mode, and coded in
either straight offset binary or binary twos complement format.
The ADS412x and ADS414x family is pin-compatible to the previous generation ADS6149 family; this
architecture enables easy migration. However, there are some important differences between the generations,
summarized in Table 1.
Table 1. Migrating from the ADS6149 Family
ADS6149 FAMILY
ADS4145 FAMILY
PINS
Pin 21 is NC (not connected)
Pin 21 is NC (not connected)
Pin 23 is MODE
Pin 23 is RESERVED in the ADS4145 family. It is reserved as a digital control pin for an (as yet) undefined function in the
next-generation ADC series.
SUPPLY
AVDD is 3.3 V
AVDD is 1.8 V
DRVDD is 1.8 V
No change
INPUT COMMON-MODE VOLTAGE
VCM is 1.5 V
VCM is 0.95 V
SERIAL INTERFACE
Protocol: 8-bit register address and 8-bit register data
No change in protocol
New serial register map
EXTERNAL REFERENCE MODE
Supported
Not supported
ADS61B49 FAMILY
ADS41B29/B49/ADS58B18 FAMILY
PINS
Pin 21 is NC (not connected)
Pin 21 is 3.3 V AVDD_BUF (supply for the analog input buffers)
Pin 23 is MODE
Pin 23 is a digital control pin for the RESERVED function.
Pin 23 functions as SNR Boost enable (B18 only).
SUPPLY
AVDD is 3.3 V
AVDD is 1.8 V, AVDD_BUF is 3.3 V
DRVDD is 1.8 V
No change
INPUT COMMON-MODE VOLTAGE
VCM is 1.5 V
VCM is 1.7 V
SERIAL INTERFACE
Protocol: 8-bit register address and 8-bit register data
No change in protocol
New serial register map
EXTERNAL REFERENCE MODE
Supported
34
Not supported
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8.2 Functional Block Diagrams
AVDD
AGND
DRVDD
DDR LVDS
Interface
DRGND
CLKP
CLKOUTP
CLOCKGEN
CLKOUTM
CLKM
D0_D1_P
D0_D1_M
D2_D3_P
D2_D3_M
Low-Latency Mode
(Default After Reset)
INP
INM
12-Bit
ADC
Sampling
Circuit
Common
Digital Functions
D4_D5_P
DDR
Serializer
D4_D5_M
D6_D7_P
D6_D7_M
D8_D9_P
D8_D9_M
Control
Interface
Reference
VCM
D10_D11_P
D10_D11_M
OVR_SDOUT
DFS
SEN
SDATA
SCLK
RESET
ADS412x
OE
Figure 93. ADS412x Block Diagram
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Functional Block Diagrams (continued)
AVDD
AGND
DRVDD
DDR LVDS
Interface
DRGND
CLKOUTP
CLKP
CLOCKGEN
CLKOUTM
CLKM
D0_D1_P
D0_D1_M
D2_D3_P
D2_D3_M
D4_D5_P
D4_D5_M
Low-Latency Mode
(Default After Reset)
INP
INM
14-Bit
ADC
Sampling
Circuit
Common
Digital Functions
D6_D7_P
DDR
Serializer
D6_D7_M
D8_D9_P
D8_D9_M
D10_D11_P
D10_D11_M
Control
Interface
Reference
VCM
D12_D13_P
D12_D13_M
OVR_SDOUT
DFS
SEN
SDATA
SCLK
RESET
ADS414x
OE
Figure 94. ADS414x Block Diagram
8.3 Feature Description
8.3.1 Digital Functions and Low Latency Mode
The device has several useful digital functions such as test patterns, gain, and offset correction. All of these
functions require extra clock cycles for operation and increase the overall latency and power of the device.
Alternately, the device has a low-latency mode in which the raw ADC output is routed to the output data pins with
a latency of 10 clock cycles. In this mode, the digital functions are bypassed. Figure 95 shows more details of the
processing after the ADC.
The device is in low-latency mode after reset. In order to use any of the digital functions, the low-latency mode
must first be disabled by setting the DIS LOW LATENCY register bit to 1. After this, the respective register bits
must be programmed as described in the following sections and in the Serial Register Map section.
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Output
Interface
14-Bit
ADC
14b
14b
Digital Functions
(Gain, Offset Correction, Test Patterns)
DDR LVDS
or CMOS
DIS LOW LATENCY Pin
Figure 95. Digital Processing Block Diagram
8.3.2 Gain for SFDR/SNR Trade-Off
The ADS412x and ADS414x include gain settings that can be used to improve SFDR performance. The gain is
programmable from 0 dB to 6 dB (in 0.5-dB steps) using the GAIN register bits. For each gain setting, the analog
input full-scale range scales proportionally, as shown in Table 2.
The SFDR improvement is achieved at the expense of SNR; for each gain setting, the SNR degrades
approximately between 0.5 dB and 1 dB. The SNR degradation is reduced at high input frequencies. As a result,
the gain is very useful at high input frequencies because the SFDR improvement is significant with marginal
degradation in SNR. Therefore, the gain can be used to trade-off between SFDR and SNR.
After a reset, the device is in low-latency mode and gain function is disabled. To use gain:
• First, disable the low-latency mode (DIS LOW LATENCY = 1).
• This setting enables the gain and puts the device in a 0-dB gain mode.
• For other gain settings, program the GAIN bits.
Table 2. Full-Scale Range Across Gains
GAIN (dB)
TYPE
FULL-SCALE (VPP)
0
Default after reset
2
1
Programmable
1.78
2
Programmable
1.59
3
Programmable
1.42
4
Programmable
1.26
5
Programmable
1.12
6
Programmable
1
8.3.3 Offset Correction
The ADS412x and ADS414x has an internal offset corretion algorithm that estimates and corrects DC offset up to
±10 mV. The correction can be enabled using the EN OFFSET CORR serial register bit. Once enabled, the
algorithm estimates the channel offset and applies the correction every clock cycle. The time constant of the
correction loop is a function of the sampling clock frequency. The time constant can be controlled using the
OFFSET CORR TIME CONSTANT register bits, as described in Table 3.
Table 3. Time Constant of Offset Correction Loop
OFFSET CORR TIME CONSTANT
TIME CONSTANT, TCCLK
(Number of Clock Cycles)
TIME CONSTANT, TCCLK × 1/fS (sec) (1)
0000
1M
8 ms
0001
2M
16 ms
0010
4M
33.4 ms
0011
8M
67 ms
0100
16M
134 ms
0101
32M
268 ms
(1)
Sampling frequency, fS = 125 MSPS.
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Table 3. Time Constant of Offset Correction Loop (continued)
OFFSET CORR TIME CONSTANT
TIME CONSTANT, TCCLK
(Number of Clock Cycles)
TIME CONSTANT, TCCLK × 1/fS (sec) (1)
0110
64M
537 ms
0111
128M
1.08 s
1000
256M
2.15 s
1001
512M
4.3 s
1010
1G
8.6 s
1011
2G
17.2 s
1100
Reserved
—
1101
Reserved
—
1110
Reserved
—
1111
Reserved
—
After the offset is estimated, the correction can be frozen by setting FREEZE OFFSET CORR = 1. Once frozen,
the last estimated value is used for the offset correction of every clock cycle. Note that offset correction is
disabled by a default after reset.
After a reset, the device is in low-latency mode and offset correction is disabled. To use offset correction:
• First, disable the low-latency mode (DIS LOW LATENCY = 1).
• Then set EN OFFSET CORR to 1 and program the required time constant.
Figure 96 shows the time response of the offset correction algorithm after it is enabled.
Output Code (LSB)
OFFSET CORRECTION
Time Response
8200
8190
8180
8170
8160
8150
8140
8130
8120
8110
8100
8090
8080
8070
8060
8050
8181
Offset of
10 LSBs
8192
Final converged value
Offset correction
converges to output
code of 8192
Offset correction
begins
-5
5
15
25
35
45
55
65
75
85
95
105
Time (ms)
Figure 96. Time Response of Offset Correction
8.3.4 Power Down
The ADS412x and ADS414x has three power-down modes: power-down global, standby, and output buffer
disable.
8.3.4.1 Power-Down Global
In this mode, the entire chip (including the ADC, internal reference, and the output buffers) are powered down,
resulting in reduced total power dissipation of about 10 mW. The output buffers are in a high-impedance state.
The wake-up time from the global power-down to data becoming valid in normal mode is typically 100 µs. To
enter the global power-down mode, set the PDN GLOBAL register bit.
8.3.4.2 Standby
In this mode, only the ADC is powered down and the internal references are active, resulting in a fast wake-up
time of 5 µs. The total power dissipation in standby mode is approximately 130 mW at 125 MSPS. To enter the
standby mode, set the STBY register bit.
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8.3.4.3 Output Buffer Disable
The output buffers can be disabled and put in a high-impedance state; wake-up time from this mode is fast,
approximately 100 ns. This can be controlled using the PDN OBUF register bit or using the OE pin.
8.3.4.4 Input Clock Stop
In addition, the converter enters a low-power mode when the input clock frequency falls below 1 MSPS. The
power dissipation is approximately 80 mW.
8.3.5 Output Data Format
Two output data formats are supported: twos complement and offset binary. Each mode can be selected using
the DATA FORMAT serial interface register bit or controlling the DFS pin in parallel configuration mode. In the
event of an input voltage overdrive, the digital outputs go to the appropriate full-scale level.
8.4 Device Functional Modes
8.4.1 Digital Output Information
The ADS412x and ADS414x provide either 14-bit data or 12-bit data, respectively, and an output clock
synchronized with the data.
8.4.1.1 Output Interface
Two output interface options are available: double data rate (DDR) LVDS and parallel CMOS. They can be
selected using the LVDS CMOS serial interface register bit or using the DFS pin.
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 97 and Figure 98.
Pins
CLKOUTP
Output Clock
CLKOUTM
D0_D1_P
Data Bits D0, D1
LVDS Buffers
D0_D1_M
D2_D3_P
Data Bits D2, D3
D2_D3_M
D4_D5_P
12-Bit
ADC Data
Data Bits D4, D5
D4_D5_M
D6_D7_P
Data Bits D6, D7
D6_D7_M
D8_D9_P
Data Bits D8, D9
D8_D9_M
D10_D11_P
Data Bits D10, D11
D10_D11_M
ADS412x
Figure 97. ADS412x LVDS Data Outputs
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Device Functional Modes (continued)
Pins
CLKOUTP
Output Clock
CLKOUTM
D0_D1_P
LVDS Buffers
Data Bits D0, D1
D0_D1_M
D2_D3_P
Data Bits D2, D3
D2_D3_M
D4_D5_P
14-Bit
ADC Data
Data Bits D4, D5
D4_D5_M
D6_D7_P
Data Bits D6, D7
D6_D7_M
D8_D9_P
Data Bits D8, D9
D8_D9_M
D10_D11_P
Data Bits D10, D11
D10_D11_M
D12_D13_P
Data Bits D12, D13
D12_D13_M
ADS414x
Figure 98. ADS414x LVDS Data Outputs
Even data bits (D0, D2, D4, and so forth) are output at the falling edge of CLKOUTP and the odd data bits (D1,
D3, D5, and so forth) are output at the rising edge of CLKOUTP. Both the rising and falling edges of CLKOUTP
must be used to capture all 14 data bits, as shown in Figure 99.
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Device Functional Modes (continued)
CLKOUTP
CLKOUTM
D0_D1_P,
D0_D1_M
D0
D1
D0
D1
D2_D3_P,
D2_D3_M
D2
D3
D2
D3
D4_D5_P,
D4_D5_M
D4
D5
D4
D5
D6_D7_P,
D6_D7_M
D6
D7
D6
D7
D8_D9_P,
D8_D9_M
D8
D9
D8
D9
D10_D11_P,
D10_D11_M
D10
D11
D10
D11
D12_D13_P,
D12_D13_M
D12
D13
D12
D13
Sample N
Sample N + 1
Figure 99. DDR LVDS Interface
8.4.1.3 LVDS Output Data and Clock Buffers
The equivalent circuit of each LVDS output buffer is shown in Figure 100. After reset, the buffer presents an
output impedance of 100 Ω to match with the external 100-Ω termination.
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.
This mode can be used when the output LVDS signal is routed to two separate receiver chips, each using a 100Ω termination. The mode can be enabled using the LVDS DATA STRENGTH and LVDS CLKOUT STRENGTH
register bits for data and output clock buffers, respectively.
The buffer output impedance behaves in the same way as a source-side series termination. By absorbing
reflections from the receiver end, it helps to improve signal integrity.
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Device Functional Modes (continued)
VDIFF
High
Low
OUTP
External
100W Load
OUTM
1.1V
ROUT
VDIFF
Low
High
Use the default buffer strength to match 100-Ω external termination (ROUT = 100 Ω). To match with a 50-Ω external
termination, set the LVDS STRENGTH bit (ROUT = 50 Ω).
Figure 100. LVDS Buffer Equivalent Circuit
8.4.1.4 Parallel CMOS Interface
In CMOS mode, each data bit is output on a separate pin as the CMOS voltage level, for every clock cycle. The
rising edge of the output clock CLKOUT can be used to latch data in the receiver. Figure 101 depicts the CMOS
output interface.
Switching noise (caused by CMOS output data transitions) can couple into the analog inputs and degrade SNR.
The coupling and SNR degradation increases as the output buffer drive is made stronger. To minimize this
degradation, the CMOS output buffers are designed with controlled drive strength. The default drive strength
ensures a wide data stable window. It is recommended to use short traces (one to two inches or 2.54 cm to 5.08
cm) terminated with less than 5-pF load capacitance, as shown in Figure 102.
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Device Functional Modes (continued)
Pins
OVR
CLKOUT
CMOS Output Buffers
D0
D1
D2
D3
¼
¼
14-Bit
ADC Data
D11
D12
D13
ADS414x
Figure 101. CMOS Output Interface
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Device Functional Modes (continued)
Use External Clock Buffer
(> 200MSPS)
Input Clock
Receiver (FPGA, ASIC, etc.)
Flip-Flops
CLKOUT
CMOS Output Buffers
D0
D1
D2
CLKIN
D0_In
D1_In
D2_In
14-Bit ADC Data
D12
D13
D12_In
D13_In
ADS414x
Use short traces between
ADC output and receiver pins (1 to 2 inches).
Figure 102. Using the CMOS Data Outputs
8.4.1.5 CMOS Interface Power Dissipation
With CMOS outputs, the DRVDD current scales with the sampling frequency and the load capacitance on every
output pin. The maximum DRVDD current occurs when each output bit toggles between 0 and 1 every clock
cycle. In actual applications, this condition is unlikely to occur. The actual DRVDD current would be determined
by the average number of output bits switching, which is a function of the sampling frequency and the nature of
the analog input signal.
Digital Current as a Result of CMOS Output Switching = CL × DRVDD × (N × fAVG)
where:
CL = load capacitance,
N × FAVG = average number of output bits switching.
(1)
Figure 86 details the current across sampling frequencies at 2-MHz analog input frequency.
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8.5 Programming
8.5.1 Device Configuration
The ADS412x and ADS414x have several modes that can be configured using a serial programming interface,
as described in Table 4, Table 5, and Table 6. In addition, the devices have two dedicated parallel pins for
quickly configuring commonly used functions. The parallel pins are DFS (analog 4-level control pin) and OE
(digital control pin). The analog control pins can be easily configured using a simple resistor divider (with 10%
tolerance resistors).
Table 4. DFS: Analog Control Pin
DESCRIPTION
(Data Format/Output Interface)
VOLTAGE APPLIED ON DFS
0, 100 mV/–0 mV
Twos complement/DDR LVDS
(3/8) AVDD ± 100 mV
Twos complement/parallel CMOS
(5/8) AVDD ± 100 mV
Offset binary/parallel CMOS
AVDD, 0 mV/–100 mV
Offset binary/DDR LVDS
Table 5. OE: Digital Control Pin
VOLTAGE APPLIED ON OE
DESCRIPTION
0
Output data buffers disabled
AVDD
Output data buffers enabled
When the serial interface is not used, the SDATA pin can also be used as a digital control pin to place the device
in standby mode. To enable this, the RESET pin must be tied high. In this mode, SEN and SCLK do not have
any alternative functions. Keep SEN tied high and SCLK tied low on the board.
Table 6. SDATA: Digital Control Pin
VOLTAGE APPLIED ON SDATA
DESCRIPTION
0
Normal operation
Logic high
Device enters standby
AVDD
(5/8) AVDD
3R
(5/8) AVDD
GND
AVDD
2R
(3/8) AVDD
3R
(3/8) AVDD
To Parallel Pin
Figure 103. Simplified Diagram to Configure DFS Pin
8.5.2 Serial Interface
The analog-to-digital converter (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), and SDATA (serial interface data)
pins. Serial shift of bits into the device is enabled when SEN is low. Serial data SDATA are latched at every
falling edge of SCLK when SEN is active (low). The serial data are loaded into the register at every 16th SCLK
falling edge when SEN is low. If the word length exceeds a multiple of 16 bits, the excess bits are ignored. Data
can be loaded in multiples of 16-bit words within a single active SEN pulse. The first eight bits form the register
address and the remaining eight bits are the register data. The interface can work with SCLK frequency from 20
MHz down to very low speeds (a few hertz) and also with non-50% SCLK duty cycle.
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8.5.2.1 Register Initialization
After power-up, the internal registers must be initialized to the default values. This initialization can be
accomplished in one of two ways:
1. Either through hardware reset by applying a high pulse on RESET pin (of width greater than 10 ns), as
shown in Figure 5; or
2. By applying a software reset. When using the serial interface, set the RESET bit (D7 in register 00h) 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.
8.5.3 Serial Register Readout
The serial register readout function allows the contents of the internal registers to be read back on the
OVR_SDOUT pin. This readback may be useful as a diagnostic check to verify the serial interface
communication between the external controller and the ADC.
After power-up and device reset, the OVR_SDOUT pin functions as an over-range indicator pin by default. When
the readout mode is enabled, OVR_SDOUT outputs the contents of the selected register serially:
1. Set the READOUT register bit to 1. This setting puts the device in serial readout mode and disables any
further writes to the internal registers except the register at address 0. Note that the READOUT bit itself is
also located in register 0. The device can exit readout mode by writing READOUT = 0. Only the contents of
the register at address 0 cannot be read in the register readout mode.
2. Initiate a serial interface cycle specifying the address of the register (A7 to A0) whose content has to be
read.
3. The device serially outputs the contents (D7 to D0) of the selected register on the OVR_SDOUT pin.
4. The external controller can latch the contents at the falling edge of SCLK.
5. To exit the serial readout mode, the reset register bit READOUT = 0 enables writes into all registers of the
device. At this point, the OVR_SDOUT pin becomes an over-range indicator pin.
Register Address A[7:0] = 0x00
SDATA
0
0
0
0
0
0
Register Data D[7:0] = 0x01
0
0
0
0
0
0
0
0
0
1
SCLK
SEN
OVR_SDOUT
(1)
a) Enable Serial Readout (READOUT = 1)
Register Address A[7:0] = 0x43
SDATA
A7
A6
A5
A4
A3
A2
Register Data D[7:0] = XX (don’t care)
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
0
1
0
0
0
0
0
0
SCLK
SEN
OVR_SDOUT
(2)
b) Read Contents of Register 0x43. This Register Has Been Initialized with 0x40 (device is put into global power-down mode).
(1)
The OVR_SDOUT pin finctions as OVR (READOUT = 0).
(2)
The OVR_SDOUT pin finctions as a serial readout (READOUT = 1).
Figure 104. Serial Readout Timing Diagram
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8.6 Register Maps
8.6.1 Serial Register Map
Table 7 summarizes the functions supported by the serial interface.
Table 7. Serial Interface Register Map (1)
REGISTER
ADDRESS
DEFAULT VALUE
AFTER RESET
REGISTER DATA
A[7:0] (Hex)
D[7:0] (Hex)
D7
D6
D5
D4
D3
D2
D1
D0
00
00
0
0
0
0
0
0
RESET
READOUT
01
00
LVDS SWING
0
0
03
00
0
0
0
0
0
0
25
00
GAIN
DISABLE
GAIN
TEST PATTERNS
26
00
0
3D
00
DATA FORMAT
3F
00
CUSTOM PATTERN HIGH D[13:6]
40
00
CUSTOM PATTERN D[5:0]
0
HIGH PERF MODE 1
0
0
0
0
LVDS
LVDS DATA
CLKOUT
STRENGTH
STRENGTH
EN
OFFSET
CORR
0
0
0
0
0
0
0
41
00
LVDS CMOS
CMOS CLKOUT
STRENGTH
EN
CLKOUT
RISE
42
00
CLKOUT FALL POSN
0
0
DIS LOW
LATENCY
STBY
0
43
00
0
PDN
GLOBAL
0
PDN OBUF
0
0
EN LVDS SWING
4A
00
0
0
0
0
0
0
0
HIGH PERF
MODE 2
BF
00
OFFSET PEDESTAL
0
0
CF
00
FREEZE
OFFSET
CORR
0
OFFSET CORR TIME CONSTANT
0
0
DF
00
0
0
LOW SPEED
0
0
(1)
0
CLKOUT RISE POSN
EN
CLKOUT
FALL
0
0
Multiple functions in a register can be programmed in a single write operation.
8.6.2 Description of Serial Registers
For best performance, two special mode register bits must be enabled: HI PERF MODE 1 and HI PERF MODE
2.
Table 8. Register Address 00h (Default = 00h)
7
0
6
0
5
0
Bits[7:2]
Always write '0'
Bit 1
RESET: Software reset applied
4
0
3
0
2
0
1
RESET
0
READOUT
This bit resets all internal registers to the default values and self-clears to 0 (default = 1).
Bit 0
READOUT: Serial readout
This bit sets the serial readout of the registers.
0 = Serial readout of registers disabled; the OVR_SDOUT pin functions as an over-voltage
indicator.
1 = Serial readout enabled; the OVR_SDOUT pin functions as a serial data readout.
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Table 9. Register Address 01h (Default = 00h)
7
6
5
4
3
2
1
0
LVDS SWING
Bits[7:2]
LVDS SWING: LVDS swing programmability (1)
000000 =
011011 =
110010 =
010100 =
111110 =
001111 =
Bits[1:0]
(1)
0
0
Default LVDS swing; ±350 mV with external 100-Ω termination
LVDS swing increases to ±410 mV
LVDS swing increases to ±465 mV
LVDS swing increases to ±570 mV
LVDS swing decreases to ±200 mV
LVDS swing decreases to ±125 mV
Always write '0'
The EN LVDS SWING register bits must be set to enable LVDS swing control.
Table 10. Register Address 03h (Default = 00h)
7
0
6
0
5
0
4
0
3
0
Bits[7:2]
Always write '0'
Bits[1:0]
HI PERF MODE 1: High performance mode 1
2
0
1
0
HI PERF MODE 1
00 = Default performance after reset
01 = Do not use
10 = Do not use
11 = For best performance across sampling clock and input signal frequencies, set the HIGH PERF
MODE 1 bits
Table 11. Register Address 25h (Default = 00h)
7
6
5
4
GAIN
Bits[7:4]
3
DISABLE GAIN
2
1
TEST PATTERNS
0
GAIN: Gain programmability
These bits set the gain programmability in 0.5dB steps.
0000
0001
0010
0011
0100
0101
0110
Bit 3
=
=
=
=
=
=
=
0-dB gain (default after reset)
0.5-dB gain
1.0-dB gain
1.5-dB gain
2.0-dB gain
2.5-dB gain
3.0-dB gain
0111
1000
1001
1010
1011
1100
=
=
=
=
=
=
3.5-dB gain
4.0-dB gain
4.5-dB gain
5.0-dB gain
5.5-dB gain
6-dB gain
DISABLE GAIN: Gain setting
This bit sets the gain.
0 = Gain enabled; gain is set by the GAIN bits only if low-latency mode is disabled
1 = Gain disabled
Bits[2:0]
TEST PATTERNS: Data capture
These bits verify data capture.
000 = Normal operation
001 = Outputs all 0s
010 = Outputs all 1s
011 = Outputs toggle pattern
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In the ADS4122/25, output data D[11:0] is an alternating sequence of 010101010101 and
101010101010.
In the ADS4142/45, output data D[13:0] is an alternating sequence of 01010101010101 and
10101010101010.
100 = Outputs digital ramp
In ADS4122/25, output data increments by one LSB (12-bit) every fourth clock cycle from code 0
to code 4095
In ADS4142/45, output data increments by one LSB (14-bit) every clock cycle from code 0 to
code 16383
101 = Output custom pattern (use registers 3Fh and 40h for setting the custom pattern)
110 = Unused
111 = Unused
Table 12. Register Address 26h (Default = 00h)
7
6
5
4
3
2
0
0
0
0
0
0
Bits[7:2]
Always write '0'
Bit 1
LVDS CLKOUT STRENGTH: LVDS output clock buffer strength
1
LVDS CLKOUT
STRENGTH
0
LVDS DATA
STRENGTH
This bit determines the external termination to be used with the LVDS output clock buffer.
0 = 100-Ω external termination (default strength)
1 = 50-Ω external termination (2x strength)
Bit 0
LVDS DATA STRENGTH: LVDS data buffer strength
This bit determines the external termination to be used with all of the LVDS data buffers.
0 = 100-Ω external termination (default strength)
1 = 50-Ω external termination (2x strength)
Table 13. Register Address 3Dh (Default = 00h)
7
6
DATA FORMAT
Bits[7:6]
5
EN OFFSET
CORR
4
3
2
1
0
0
0
0
0
0
1
CUSTOM
PATTERN D7
0
CUSTOM
PATTERN D6
DATA FORMAT: Data format selection
These bits selects the data format.
00 = The DFS pin controls data format selection
10 = Twos complement
11 = Offset binary
Bit 5
ENABLE OFFSET CORR: Offset correction setting
This bit sets the offset correction.
0 = Offset correction disabled
1 = Offset correction enabled
Bits[4:0]
Always write '0'
Table 14. Register Address 3Fh (Default = 00h)
7
CUSTOM
PATTERN D13
6
CUSTOM
PATTERN D12
5
CUSTOM
PATTERN D11
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4
CUSTOM
PATTERN D10
3
CUSTOM
PATTERN D9
2
CUSTOM
PATTERN D8
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CUSTOM PATTERN (1)
Bits[7:0]
These bits set the custom pattern.
(1)
For the ADS414x, output data bits 13 to 0 are CUSTOM PATTERN D[13:0]. For the ADS412x, output data bits 11 to 0 are CUSTOM
PATTERN D[13:2].
Table 15. Register Address 40h (Default = 00h)
7
CUSTOM
PATTERN D5
Bits[7:2]
6
CUSTOM
PATTERN D4
5
CUSTOM
PATTERN D3
4
CUSTOM
PATTERN D2
3
CUSTOM
PATTERN D1
2
CUSTOM
PATTERN D0
1
0
0
0
CUSTOM PATTERN (1)
These bits set the custom pattern.
Bits[1:0]
(1)
Always write '0'
For the ADS414x, output data bits 13 to 0 are CUSTOM PATTERN D[13:0]. For the ADS412x, output data bits 11 to 0 are CUSTOM
PATTERN D[13:2].
Table 16. Register Address 41h (Default = 00h)
7
6
LVDS CMOS
Bits[7:6]
5
4
CMOS CLKOUT STRENGTH
3
EN CLKOUT
RISE
2
1
CLKOUT RISE POSN
0
EN CLKOUT
FALL
LVDS CMOS: Interface selection
These bits select the interface.
00 = The DFS pin controls the selection of either LVDS or CMOS interface
10 = The DFS pin controls the selection of either LVDS or CMOS interface
01 = DDR LVDS interface
11 = Parallel CMOS interface
Bits[5:4]
CMOS CLKOUT STRENGTH
Controls strength of CMOS output clock only.
00 = Maximum strength (recommended and used for specified timings)
01 = Medium strength
10 = Low strength
11 = Very low strength
Bit 3
ENABLE CLKOUT RISE
0 = Disables control of output clock rising edge
1 = Enables control of output clock rising edge
Bits[2:1]
CLKOUT RISE POSN: CLKOUT rise control
Controls position of output clock rising edge
LVDS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 500 ps, hold increases by 500 ps
10 = Data transition is aligned with rising edge
11 = Setup reduces by 200 ps, hold increases by 200 ps
CMOS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 100 ps, hold increases by 100 ps
10 = Setup reduces by 200 ps, hold increases by 200 ps
11 = Setup reduces by 1.5 ns, hold increases by 1.5 ns
Bit 0
50
ENABLE CLKOUT FALL
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0 = Disables control of output clock fall edge
1 = Enables control of output clock fall edge
Table 17. Register Address 42h (Default = 00h)
7
6
CLKOUT FALL CTRL
Bits[7:6]
5
4
0
0
3
DIS LOW
LATENCY
2
1
0
STBY
0
0
CLKOUT FALL CTRL
Controls position of output clock falling edge
LVDS interface:
00 = Default position (timings are specified in this condition)
01 = Setup reduces by 400 ps, hold increases by 400 ps
10 = Data transition is aligned with rising edge
11 = Setup reduces by 200 ps, hold increases by 200 ps
CMOS interface:
00 = Default position (timings are specified in this condition)
01 = Falling edge is advanced by 100 ps
10 = Falling edge is advanced by 200 ps
11 = Falling edge is advanced by 1.5 ns
Bits[5:4]
Always write '0'
Bit 3
DIS LOW LATENCY: Disable low latency
This bit disables low-latency mode,
0 = Low-latency mode is enabled. Digital functions such as gain, test patterns and offset correction
are disabled
1 = Low-latency mode is disabled. This setting enables the digital functions. See the Digital
Functions and Low Latency Mode section.
Bit 2
STBY: Standby mode
This bit sets the standby mode.
0 = Normal operation
1 = Only the ADC and output buffers are powered down; internal reference is active; wake-up time
from standby is fast
Bits[1:0]
Always write '0'
Table 18. Register Address 43h (Default = 00h)
7
0
6
PDN GLOBAL
5
0
Bit 0
Always write '0'
Bit 6
PDN GLOBAL: Power-down
4
PDN OBUF
3
0
2
0
1
0
EN LVDS SWING
This bit sets the state of operation.
0 = Normal operation
1 = Total power down; the ADC, internal references, and output buffers are powered down; slow
wake-up time.
Bit 5
Always write '0'
Bit 4
PDN OBUF: Power-down output buffer
This bit set the output data and clock pins.
0 = Output data and clock pins enabled
1 = Output data and clock pins powered down and put in high- impedance state
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Bits[3:2]
Always write '0'
Bits[1:0]
EN LVDS SWING: LVDS swing control
00
01
10
11
=
=
=
=
LVDS swing control using LVDS SWING register bits is disabled
Do not use
Do not use
LVDS swing control using LVDS SWING register bits is enabled
Table 19. Register Address 4Ah (Default = 00h)
7
6
5
4
3
2
1
0
0
0
0
0
0
0
Bits[7:1]
Always write '0'
Bit[0]
HI PERF MODE 2: High performance mode 2
0
HI PERF
MODE 2
This bit is recommended for high input signal frequencies greater than 230 MHz.
0 = Default performance after reset
1 = For best performance with high-frequency input signals, set the HIGH PERF MODE 2 bit
Table 20. Register Address BFh (Default = 00h)
7
Bits[7:2]
6
5
4
OFFSET PEDESTAL
3
2
1
0
0
0
OFFSET PEDESTAL
These bits set the offset pedestal.
When the offset correction is enabled, the final converged value after the offset is corrected is the
ADC mid-code value. A pedestal can be added to the final converged value by programming these
bits.
Bits[1:0]
ADS414x VALUE
PEDESTAL
011111
011110
011101
—
000000
—
111111
111110
—
100000
31LSB
30LSB
29LSB
—
0LSB
—
–1LSB
–2LSB
—
–32LSB
Always write '0'
Table 21. Register Address CFh (Default = 00h)
7
FREEZE
OFFSET
CORR
52
6
5
0
4
3
2
OFFSET CORR TIME CONSTANT
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1
0
0
0
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Bit 7
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FREEZE OFFSET CORR
This bit sets the freeze offset correction.
0 = Estimation of offset correction is not frozen (bit EN OFFSET CORR must be set)
1 = Estimation of offset correction is frozen (bit EN OFFSET CORR must be set). When frozen, the
last estimated value is used for offset correction every clock cycle. See the Offset Correction
section.
Bit 6
Always write '0'
Bits[5:2]
OFFSET CORR TIME CONSTANT
These bits set the offset correction time constant for the correction loop time constant in number of
clock cycles.
Bits[1:0]
VALUE
TIME CONSTANT (Number of Clock Cycles)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1M
2M
4M
8M
16M
32M
64M
128M
256M
512M
1G
2G
Always write '0'
Table 22. Register Address DFh (Default = 00h)
7
0
6
0
5
4
LOW SPEED
Bits[7:6]
Always write '0'
Bits[5:4]
LOW SPEED: Low-speed mode
3
0
2
0
1
0
0
0
For the ADS4122/42, the low-speed mode is enabled by default after reset.
00, 01, 10, 11 = Do not use
For the ADS4125/55 only:
00, 01, 10 = Low-speed mode disabled (default state after reset); this setting is recommended for
sampling rates greater than 80 MSPS.
11 = Low-speed mode enabled; this setting is recommended for sampling rates less than or equal
to 80 MSPS.
Bits[3:0]
Always write '0'
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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
The ADS412x and ADS414x are lower sampling speed members of the ADS41xx family of ultralow power
analog-to-digital converters (ADCs). 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 10 clock cycles. The output is available as 14-bit
data or 12-bit data, in DDR LVDS mode or CMOS mode, and coded in either straight offset binary or binary twos
complement format.
9.1.1 Analog Input
The analog input consists of a switched-capacitor-based, differential, sample-and-hold architecture. This
differential topology results in very good ac performance even for high input frequencies at high sampling rates.
The INP and INM pins must be externally biased around a common-mode voltage of 0.95 V, available on the
VCM pin. For a full-scale differential input, each input INP and INM pin must swing symmetrically between (VCM
+ 0.5 V) and (VCM – 0.5 V), resulting in a 2-VPP differential input swing. The input sampling circuit has a high 3dB bandwidth that extends up to 550 MHz (measured from the input pins to the sampled voltage). Figure 105
shows an equivalent circuit for the analog input.
Sampling
Switch
LPKG
2nH
INP
10W
CBOND
1pF
RESR
200W
100W
INM
CPAR2
1pF
RESR
200W
CSAMP
2pF
CPAR1
0.5pF
RON
15W
100W
CBOND
1pF
RON
15W
3pF
3pF
LPKG
2nH
Sampling
Capacitor
RCR Filter
RON
15W
CPAR2
1pF
CSAMP
2pF
Sampling
Capacitor
Sampling
Switch
Figure 105. Analog Input Equivalent Circuit
9.1.1.1 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 5-Ω to 15-Ω resistor in series with each input pin is
recommended to damp out ringing caused by package parasitics. It is also necessary to present low impedance
(less than 50 Ω) for the common-mode switching currents. This impedance can be achieved by using two
resistors from each input terminated to the common-mode voltage (VCM).
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Application Information (continued)
Note that the device includes an internal R-C filter from each input to ground. The purpose of this filter is to
absorb the glitches caused by the opening and closing of the sampling capacitors. The cutoff frequency of the RC filter involves a trade-off. A lower cutoff frequency (larger C) absorbs glitches better, but also reduces the input
bandwidth and the maximum input frequency that can be supported. On the other hand, with no internal R-C
filter, high input frequency can be supported but now the sampling glitches must be supplied by the external
driving circuit. The inductance of the package bond wires limits the ability of the external driving circuit to support
the sampling glitches.
In the ADS412x and ADS414x, the R-C component values have been optimized while supporting high input
bandwidth (550 MHz). However, in applications where very high input frequency support is not required, filtering
of the glitches can be improved further with an external R-C-R filter; see Figure 108 and Figure 109).
In addition, the drive circuit may have to be designed to provide a low insertion loss over the desired frequency
range and matched impedance to the source. While designing the drive circuit, the ADC impedance must be
considered. Figure 106 and Figure 107 show the impedance (ZIN = RIN || CIN) looking into the ADC input pins.
5.0
Differential Input Capacitance (pF)
Differential Input Resistance (kW)
100.00
10.00
1.00
0.10
0.01
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Input Frequency (GHz)
Figure 106. ADC Analog Input Resistance (RIN) Across
Frequency
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Input Frequency (GHz)
Figure 107. ADC Analog Input Capacitance (CIN) Across
Frequency
9.1.1.2 Driving Circuit
Two example driving circuit configurations are shown in Figure 108 and Figure 109—one optimized for low
bandwidth (low input frequencies) and the other one for high bandwidth to support higher input frequencies. In
Figure 108, an external R-C-R filter with 3.3 pF is used to help absorb sampling glitches. The R-C-R filter limits
the bandwidth of the drive circuit, making it suitable for low input frequencies (up to 250 MHz). Transformers
such as ADT1-1WT or WBC1-1 can be used up to 250 MHz.
For higher input frequencies, the R-C-R filter can be dropped. Together with the lower series resistors (5 Ω to 10
Ω), this drive circuit provides higher bandwidth to support frequencies up to 500 MHz (as shown in Figure 109). A
transmission line transformer such as ADTL2-18 can be used.
Note that both the drive circuits have been terminated by 50 Ω near the ADC side. The termination is
accomplished by a 25-Ω resistor from each input to the 0.95-V common-mode (VCM) from the device. This
termination allows the analog inputs to be biased around the required common-mode voltage.
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Application Information (continued)
10W to 15W
T2
3.6nH
INP
T1
0.1mF
0.1mF
25W
50W
RIN
3.3pF
25W
CIN
50W
INM
1:1
1:1
10W to 15W
3.6nH
VCM
ADS41xx
Figure 108. Drive Circuit with Low Bandwidth (for Low Input Frequencies)
5W to 10W
T2
T1
INP
0.1mF
0.1mF
25W
RIN
CIN
25W
INM
1:1
1:1
5W to 10W
VCM
ADS41xx
Figure 109. Drive Circuit with High Bandwidth (for High Input Frequencies)
The mismatch in the transformer parasitic capacitance (between the windings) results in degraded even-order
harmonic performance. Connecting two identical RF transformers back-to-back helps minimize this mismatch and
good performance is obtained for high-frequency input signals. An additional termination resistor pair may be
required between the two transformers, as shown in Figure 108 and Figure 109. 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).
Figure 108 and Figure 109 use 1:1 transformers with a 50-Ω source. As explained in the Drive Circuit
Requirements section, this architecture helps to present a low source impedance to absorb sampling glitches.
With a 1:4 transformer, the source impedance is 200 Ω. The higher source impedance is unable to absorb the
sampling glitches effectively and can lead to degradation in performance (compared to using 1:1 transformers).
In almost all cases, either a bandpass or low-pass filter is needed to obtain the desired dynamic performance, as
shown in Figure 110. Such a filter presents low source impedance at the high frequencies corresponding to the
sampling glitch and helps avoid the performance loss with the high source impedance.
10W
Bandpass or
Low-Pass
Filter
Differential
Input Signal
0.1mF
INP
100W
ADS41xx
100W
INM
10W
VCM
Figure 110. Drive Circuit with 1:4 Transformer
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Application Information (continued)
9.1.1.3 Input Common-Mode
To ensure a low-noise, common-mode reference, the VCM pin is filtered with a 0.1-µF low-inductance capacitor
connected to ground. The VCM pin is designed to directly drive the ADC inputs. Each ADC input pin sinks a
common-mode current of approximately 0.6 µA per MSPS of clock frequency.
9.1.2 Clock Input
The ADS412x and ADS414x clock inputs can be driven differentially (sine, LVPECL, or LVDS) or single-ended
(LVCMOS), with little or no difference in performance between them. The common-mode voltage of the clock
inputs is set to VCM using internal 5-kΩ resistors. This setting allows the use of transformer-coupled drive
circuits for sine-wave clock or ac-coupling for LVPECL and LVDS clock sources. Figure 111 shows an equivalent
circuit for the input clock.
Clock Buffer
LPKG
1nH
20W
CLKP
CBOND
1pF
RESR
100W
LPKG
1nH
5kW
2pF
20W
CEQ
CEQ
VCM
5kW
CLKM
CBOND
1pF
RESR
100W
NOTE: CEQ is 1 pF to 3 pF, and is the equivalent input capacitance of the clock buffer.
Figure 111. Input Clock Equivalent Circuit
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Application Information (continued)
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 112. For best performance, the clock inputs must be driven differentially, reducing
susceptibility to common-mode noise. For high input frequency sampling, it is recommended to use a clock
source with very low jitter. Band-pass filtering of the clock source can help reduce the effects of jitter. There is no
change in performance with a non-50% duty cycle clock input. Figure 113 shows a differential circuit.
CMOS
Clock Input
0.1mF
CLKP
VCM
0.1mF
CLKM
Figure 112. Single-Ended Clock Driving Circuit
0.1mF
CLKP
Differential Sine-Wave,
PECL, or LVDS
Clock Input
0.1mF
CLKM
Figure 113. Differential Clock Driving Circuit
9.1.3 Input Overvoltage Indication (OVR Pin)
The device has an OVR pin that provides information about analog input overload. At any clock cycle, if the
sampled input voltage exceeds the positive or negative full-scale range, the OVR pin goes high. The OVR
remains high as long as the overload condition persists. The OVR pin is a CMOS output buffer (running off
DRVDD supply), independent of the type of output data interface (DDR LVDS or CMOS).
For a positive overload, the D[13:0] output data bits are 3FFFh in offset binary output format and 1FFFh in twos
complement output format. For a negative input overload, the output code is 0000h in offset binary output format
and 2000h in twos complement output format.
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9.2 Typical Application
An example schematic for a typical application of the ADS414x is shown in Figure 114.
LVPECL
Clock Driver
AVDD
100
0.1 µF
0.1 µF
150
150
DFS
CLKOUTP
CLKOUTM
OVR_SDOUT
DRVDD
DRGND
7
6
5
4
3
2
1
0.1 µF
OE
AVDD
0.1 µF
8
50
0.1 µF
9
5
0.1 µF
To FPGA
AVDD
5
DRVDD
To FPGA
AGND
50
CLKP 10
50
0.1 µF
CLKM 11
AGND 12
0.1 µF
ADC
Driver 50
Set by mode of
operation
0.1 µF
VCM 13
48 D12_D13_P
AGND 14
47 D12_D13_M
INP 15
46 D10_D11_P
INM 16
45 D10_D11_M
AGND 17
AVDD
18
44 D8_D9_P
AGND 19
42 D6_D7_P
AVDD 20
41 D6_D7_M
NC 21
40 D4_D5_P
43 D8_D9_M
36 DRGND
35 DRVDD
34 D0_D1_P
33 D0_D1_M
22
32 NC
22
31 NC
30 RESET
29 SCLK
28 SDATA
37 D2_D3_M
AVDD
27 SEN
38 D2_D3_P
AVDD 24
0.1 µF
26 AVDD
39 D4_D5_M
25 AGND
AVDD 22
RESERVED 23
AVDD
FPGA
22
0.1 µF
0.1 µF
22
To FPGA
DVDD
AVDD
SPI Controller
Figure 114. Example Schematic for ADS414x
9.2.1 Design Requirements
Example design requirements are listed in Table 23 for the ADC portion of the signal chain. These do not
necessary reflect the requirements of an actual system, but rather demonstrate why the ADS412x and ADS414x
may be chosen for a system based on a set of requirements.
Table 23. Example Design Requirements for ADS412x and ADS414x
DESIGN PARAMETER
EXAMPLE DESIGN REQUIREMENT
ADS4128 CAPABILITY
Sampling rate
≥ 122.88 Msps
Max sampling rate: 125 Msps
Input frequency
> 125 MHz to accommodate full 2nd nyquist zone
Large signal –3 dB bandwith: 400 MHz operation
SNR
> 68 dBFS at –1dFBS, 170 MHz
72.2 dBFS at –1dBFS, 170 MHz
SFDR
>77dBc at –1dFBS, 170 MHz
81 dBc at –1 dBFS, 170 MHz
Input full scale voltage
2 Vpp
2 Vpp
Overload recovery time
< 3 clock cycles
1 clock cycle
Digital interface
Parallel LVDS
Parallel LVDS
Power consumption
< 200 mW per channel
153 mW per channel
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Typical Application (continued)
9.2.2 Detailed Design Procedure
9.2.2.1 Analog Input
The analog input of the ADS412x and ADS414x is typically driven by a fully differential amplifier. The amplifier
must have sufficient bandwidth for the frequencies of interest. The noise and distortion performance of the
amplifier will affect the combined performance of the ADC and amplifier. The amplifier is often AC coupled to the
ADC to allow both the amplifier and ADC to operate at the optimal common mode voltages. It is possible to DC
couple the amplifier to the ADC if required. An alternate approach is to drive the ADC using transformers. DC
coupling cannot be used with the transformer approach.
9.2.2.2 Clock Driver
The ADS412x and ADS414x should be driven by a high performance clock driver such as a clock jitter cleaner.
The clock needs to have low noise to maintain optimal performance. LVPECL is the most common clocking
interface, but LVDS and LVCMOS can be used as well. It is not advised to drive the clock input from an FPGA
unless the noise degradation can be tolerated, such as for input signals near DC where the clock noise impact is
minimal.
9.2.2.3 Digital Interface
The ADS412x and ADS414x supports both LVDS and CMOS interfaces. The LVDS interface should be used for
best performance when operating at maximum sampling rate. The LVDS outputs can be connected directly to the
FPGA without any additional components. When using CMOS outputs resistors should be placed in series with
the outputs to reduce the output current spikes to limit the performance degradation. The resistors should be
large enough to limit current spikes but not so large as to significantly distort the digital output waveform. An
external CMOS buffer should be used when driving distances greater than a few inches to reduce ground bounce
within the ADC.
9.2.3 Application Curve
Figure 115 shows the results of a 100-MHz signal sampled at 65 MHz captured by the ADS4122.
0
Amplitude (dBFS)
-20
-40
-60
-80
-100
-120
0
10
20
Frequency (MHz)
30
D001
SNR = 70.11 dBFs
SFDR= 87.74 dBFs
THD= 84.33 dBs
SINAD= 70.03 dBFs
Figure 115. 100-MHz Signal Captured by ADS4122
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10 Power Supply Recommendations
The ADS412x and ADS414x has two power supplies, one analog (AVDD) and one digital (DRVDD) supply. Both
supplies have a nominal voltage of 1.8 V. The AVDD supply is noise sensitive and the digital supply is not.
10.1 Sharing DRVDD and AVDD Supplies
For best performance the AVDD supply should be driven by a low noise linear regulator (LDO) and separated
from the DRVDD supply. It is possible to have AVDD and DRVDD share a single supply but they should be
isolated by a ferrite bead and bypass capacitors, in a PI-filter configuration, at a minimum. The digital noise will
be concentrated at the sampling frequency and harmonics of the sampling frequency and could contain noise
related to the sampled signal. While developing schematics, it is a good idea to leave extra placeholders for
additional supply filtering.
10.2 Using DC-DC Power Supplies
DC-DC switching power supplies can be used to power DRVDD without issue. It is also possible to power AVDD
from a switching regulator. Noise and spurs on the AVDD power supply will affect the SNR and SFDR of the
ADC and will show up near DC and as a modulated component around the input frequency. If a switching
regulator is used, then it should be designed to have minimal voltage ripple. Supply filtering should be used to
limit the amount of spurious noise at the AVDD supply pins. Extra placeholders should be placed on the
schematic for additional filtering. Optimization of filtering in the final system will likely be needed to achieve the
desired performance. The choice of power supply ultimately depends on the system requirements. For instance if
very low phase noise is required then use of a switching regulator is not recommended.
10.3 Power Supply Bypassing
Because the ADS412x and ADS414x already includes internal decoupling, minimal external decoupling can be
used without loss in performance. Note that decoupling capacitors can help filter external power-supply noise;
thus, the optimum number of capacitors depends on the actual application. A 0.1-µF capacitor is recommended
near each supply pin. The decoupling capacitors should be placed very close to the converter supply pins.
11 Layout
11.1 Layout Guidelines
11.1.1 Grounding
A single ground plane is sufficient to give good performance, provided the analog, digital, and clock sections of
the board are cleanly partitioned. See ADS414x, ADS412x EVM User GuideSLWU067 for details on layout and
grounding.
11.1.2 Supply Decoupling
Because the ADS412x and ADS414x already include internal decoupling, minimal external decoupling can be
used without loss in performance. Note that decoupling capacitors can help filter external power-supply noise, so
the optimum number of capacitors depends on the actual application. The decoupling capacitors should be
placed very close to the converter supply pins.
11.1.3 Exposed Pad
In addition to providing a path for heat dissipation, the thermal pad is also electrically internally connected to the
digital ground. Therefore, it is necessary to solder the exposed pad to the ground plane for best thermal and
electrical performance. For detailed information, see application notes QFN Layout Guidelines, SLOA122) and
QFN/SON PCB Attachment, SLUA271, both available for download at www.ti.com.
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11.2 Layout Example
Figure 116. ADS412x and ADS414x EVM PCB Layout
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12 Device and Documentation Support
12.1 Device Support
12.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
12.1.2 Device Nomenclature
Analog Bandwidth The analog input frequency at which the power of the fundamental is reduced by 3 dB with
respect to the low-frequency value.
Aperture Delay The delay in time between the rising edge of the input sampling clock and the actual time at
which the sampling occurs.
This delay is different across channels. The maximum variation is specified as aperture
delay variation (channel-to-channel).
Aperture Uncertainty (Jitter) The sample-to-sample variation in aperture delay.
Clock Pulse Width/Duty Cycle The duty cycle of a clock signal is the ratio of the time the clock signal remains
at a logic high (clock pulse width) to the period of the clock signal.
Duty cycle is typically expressed as a percentage. A perfect differential sine-wave clock
results in a 50% duty cycle.
Maximum Conversion Rate The maximum sampling rate at which specified operation is given.
All parametric testing is performed at this sampling rate unless otherwise noted.
Minimum Conversion Rate The minimum sampling rate at which the ADC functions.
Differential Nonlinearity (DNL) The DNL is the deviation of any single step from this ideal value, measured in
units of LSBs.
An ideal ADC exhibits code transitions at analog input values spaced exactly 1 LSB apart.
Integral Nonlinearity (INL) The INL is the deviation of the ADC transfer function from a best fit line determined
by a least squares curve fit of that transfer function, measured in units of LSBs.
Gain Error
Gain error is the deviation of the ADC actual input full-scale range from its ideal value.
The gain error is given as a percentage of the ideal input full-scale range. Gain error has two
components: error as a result of reference inaccuracy and error as a result of the channel.
Both errors are specified independently as EGREF and EGCHAN.
To a first-order approximation, the total gain error is ETOTAL ~ EGREF + EGCHAN.
For example, if ETOTAL = ±0.5%, the full-scale input varies from (1 – 0.5/100) x FSideal to (1 +
0.5/100) x FSideal.
Offset Error The offset error is the difference, given in number of LSBs, between the ADC actual average idle
channel output code and the ideal average idle channel output code.
This quantity is often mapped into millivolts.
Temperature Drift The temperature drift coefficient (with respect to gain error and offset error) specifies the
change per degree Celsius of the parameter from TMIN to TMAX.
It is calculated by dividing the maximum deviation of the parameter across the TMIN to TMAX
range by the difference TMAX – TMIN.
Signal-to-Noise Ratio SNR is the ratio of the power of the fundamental (PS) to the noise floor power (PN),
excluding the power at dc and the first nine harmonics.
SNR = 10Log10
PS
PN
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Device Support (continued)
SNR is either given in units of dBc (dB to carrier) when the absolute power of the
fundamental is used as the reference, or dBFS (dB to full-scale) when the power of the
fundamental is extrapolated to the converter full-scale range.
Signal-to-Noise and Distortion (SINAD) SINAD is the ratio of the power of the fundamental (PS) to the power
of all the other spectral components including noise (PN) and distortion (PD), but excluding dc.
SINAD = 10Log10
PS
PN + PD
(3)
SINAD is either given in units of dBc (dB to carrier) when the absolute power of the
fundamental is used as the reference, or dBFS (dB to full-scale) when the power of the
fundamental is extrapolated to the converter full-scale range.
Effective Number of Bits (ENOB) ENOB is a measure of the converter performance as compared to the
theoretical limit based on quantization noise.
ENOB =
SINAD - 1.76
6.02
(4)
Total Harmonic Distortion (THD) THD is the ratio of the power of the fundamental (PS) to the power of the first
nine harmonics (PD).
THD = 10Log10
PS
PN
(5)
THD is typically given in units of dBc (dB to carrier).
Spurious-Free Dynamic Range (SFDR) The ratio of the power of the fundamental to the highest other spectral
component (either spur or harmonic).
SFDR is typically given in units of dBc (dB to carrier).
Two-Tone Intermodulation Distortion IMD3 is the ratio of the power of the fundamental (at frequencies f1 and
f2) to the power of the worst spectral component at either frequency 2f1 – f2 or 2f2 – f1.
IMD3 is either given in units of dBc (dB to carrier) when the absolute power of the
fundamental is used as the reference, or dBFS (dB to full-scale) when the power of the
fundamental is extrapolated to the converter full-scale range.
DC Power-Supply Rejection Ratio (DC PSRR) DC PSSR is the ratio of the change in offset error to a change
in analog supply voltage.
The dc PSRR is typically given in units of mV/V.
AC Power-Supply Rejection Ratio (AC PSRR) AC PSRR is the measure of rejection of variations in the supply
voltage by the ADC.
If ΔVSUP is the change in supply voltage and ΔVOUT is the resultant change of the ADC
output code (referred to the input), then:
DVOUT
PSRR = 20Log 10
(Expressed in dBc)
DVSUP
(6)
Voltage Overload Recovery The number of clock cycles taken to recover to less than 1% error after an
overload on the analog inputs.
This is tested by separately applying a sine wave signal with 6dB positive and negative
overload. The deviation of the first few samples after the overload (from the expected values)
is noted.
Common-Mode Rejection Ratio (CMRR) CMRR is the measure of rejection of variation in the analog input
common-mode by the ADC.
If ΔVCM_IN is the change in the common-mode voltage of the input pins and ΔVOUT is the
resulting change of the ADC output code (referred to the input), then:
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Device Support (continued)
CMRR = 20Log10
DVOUT
(Expressed in dBc)
DVCM
(7)
Crosstalk (only for multi-channel ADCs) This is a measure of the internal coupling of a signal from an
adjacent channel into the channel of interest. It is specified separately for coupling from the
immediate neighboring channel (near-channel) and for coupling from channel across the package
(far-channel).
It is usually measured by applying a full-scale signal in the adjacent channel. Crosstalk is the
ratio of the power of the coupling signal (as measured at the output of the channel of
interest) to the power of the signal applied at the adjacent channel input. It is typically
expressed in dBc.
12.2 Documentation Support
12.2.1 Related Documentation
For Related documentation, see the following:
• QFN Layout Guidelines (SLOA122)
• QFN/SON PCB Attachment (SLUA271)
• ADS4226 Evaluation Module (SLWU067)
12.3 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 24. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
ADS4122
Click here
Click here
Click here
Click here
Click here
ADS4125
Click here
Click here
Click here
Click here
Click here
ADS4142
Click here
Click here
Click here
Click here
Click here
ADS4145
Click here
Click here
Click here
Click here
Click here
12.4 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.5 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.6 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
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12.7 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.
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PACKAGE OPTION ADDENDUM
www.ti.com
11-Jul-2017
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
ADS4122IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4122
ADS4122IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4122
ADS4125IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4125
ADS4125IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4125
ADS4142IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4142
ADS4142IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4142
ADS4145IRGZR
ACTIVE
VQFN
RGZ
48
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4145
ADS4145IRGZT
ACTIVE
VQFN
RGZ
48
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-3-260C-168 HR
-40 to 85
AZ4145
(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
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