SBAS533E March   2011  – February 2023 ADS4222 , ADS4225 , ADS4226 , ADS4242 , ADS4245 , ADS4246

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin Functions – LVDS Mode
    2.     Pin Functions – CMOS Mode
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics: ADS4246, ADS4245, ADS4242
    6. 7.6  Electrical Characteristics: ADS4226, ADS4225, ADS4222
    7. 7.7  Electrical Characteristics: General
    8. 7.8  Digital Characteristics
    9. 7.9  Timing Requirements: LVDS and CMOS Modes (1)
    10. 7.10 Serial Interface Timing Characteristics (1)
    11. 7.11 Reset Timing (Only When Serial Interface Is Used)
    12. 7.12 Typical Characteristics
      1. 7.12.1 ADS4246
      2. 7.12.2 ADS4245
      3. 7.12.3 ADS4242
      4. 7.12.4 ADS4226
      5. 7.12.5 ADS4225
      6. 7.12.6 ADS4222
      7. 7.12.7 General
      8. 7.12.8 Contour
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Analog Input
        1. 8.3.1.1 Drive Circuit Requirements
        2. 8.3.1.2 Driving Circuit
      2. 8.3.2 Clock Input
      3. 8.3.3 Digital Functions
      4. 8.3.4 Gain for SFDR/SNR Trade-off
      5. 8.3.5 Offset Correction
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Down
        1. 8.4.1.1 Global Power-Down
        2. 8.4.1.2 Channel Standby
        3. 8.4.1.3 Input Clock Stop
    5. 8.5 Programming
      1. 8.5.1 47
      2. 8.5.2 Parallel Configuration Only
      3. 8.5.3 Serial Interface Configuration Only
      4. 8.5.4 Using Both Serial Interface and Parallel Controls
      5. 8.5.5 Parallel Configuration Details
      6. 8.5.6 Serial Interface Details
        1. 8.5.6.1 Register Initialization
        2. 8.5.6.2 Serial Register Readout
      7. 8.5.7 Digital Output Information
        1. 8.5.7.1 Output Interface
        2. 8.5.7.2 DDR LVDS Outputs
        3. 8.5.7.3 LVDS Buffer
        4. 8.5.7.4 Parallel CMOS Interface
        5. 8.5.7.5 CMOS Interface Power Dissipation
        6. 8.5.7.6 Multiplexed Mode of Operation
        7. 8.5.7.7 Output Data Format
    6. 8.6 Register Maps
      1. 8.6.1 64
      2. 8.6.2 Description Of Serial Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Analog Input
        2. 9.2.2.2 Clock Driver
        3. 9.2.2.3 Digital Interface
        4. 9.2.2.4 SNR and Clock Jitter
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Sharing DRVDD and AVDD Supplies
      2. 9.3.2 Using DC/DC Power Supplies
      3. 9.3.3 Power Supply Bypassing
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Grounding
        2. 9.4.1.2 Supply Decoupling
        3. 9.4.1.3 Exposed Pad
        4. 9.4.1.4 Routing Analog Inputs
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.6.2 Description Of Serial Registers

76543210
000000RESETREADOUT
Bits[7:2]Always write 0
Bit 1RESET: Software reset applied
This bit resets all internal registers to the default values and self-clears to 0 (default = 1).
Bit 0READOUT: Serial readout
This bit sets the serial readout of the registers.
0 = Serial readout of registers disabled; the SDOUT pin is placed in high-impedance state.
1 = Serial readout enabled; the SDOUT pin functions as a serial data readout with CMOS logic levels running from the DRVDD supply. See the Serial Register Readout section.
76543210
LVDS SWING00
Bits[7:2]LVDS SWING: LVDS swing programmability
These bits program the LVDS swing. Set the EN LVDS SWING bit to 1 before programming swing.
000000 = Default LVDS swing; ±350 mV with external 100-Ω termination
011011 = LVDS swing increases to ±410 mV
110010 = LVDS swing increases to ±465mV
010100 = LVDS swing increases to ±570 mV
111110 = LVDS swing decreases to ±200 mV
001111 = LVDS swing decreases to ±125mV
Bits[1:0]Always write 0
76543210
000000HIGH PERF MODE
Bits[7:2]Always write 0
Bits[1:0]HIGH PERF MODE: High-performance mode
00 = Default performance
01 = Do not use
10 = Do not use
11 = Obtain best performance across sample clock and input signal frequencies
76543210
CH A GAIN0CH A TEST PATTERNS
Bits[7:4]CH A GAIN: Channel A gain programmability
These bits set the gain programmability in 0.5-dB steps for channel A.
0000 = 0-dB gain (default after reset)
0001 = 0.5-dB gain
0010 = 1-dB gain
0011 = 1.5-dB gain
0100 = 2-dB gain
0101 = 2.5-dB gain
0110 = 3-dB gain
0111 = 3.5-dB gain
1000 = 4-dB gain
1001 = 4.5-dB gain
1010 = 5-dB gain
1011 = 5.5-dB gain
1100 = 6-dB gain
Bit 3Always write 0
Bits[2:0]CH A TEST PATTERNS: Channel A data capture
These bits verify data capture for channel A.
000 = Normal operation
001 = Outputs all 0s
010 = Outputs all 1s
011 = Outputs toggle pattern.
For the ADS424x, output data D[13:0] are an alternating sequence of 10101010101010 and 01010101010101.
For the ADS422x, the output data D[11:0] are an alternating sequence of 101010101010 and 010101010101.
100 = Outputs digital ramp.
For the ADS424x, output data increment by one LSB (14-bit) every clock cycle from code 0 to code 16383.
For the ADS422x, output data increment by one LSB (12-bit) every fourth clock cycle from code 0 to code 4095.
101 = Outputs custom pattern; use registers 3Fh and 40h to set the custom pattern
110 = Unused
111 = Unused
76543210
000DATA FORMAT000
Bits[7:5]Always write 0
Bits[4:3]DATA FORMAT: Data format selection
00 = Twos complement
01 = Twos complement
10 = Twos complement
11 = Offset binary
Bits[2:0]Always write 0
76543210
CH B GAIN0CH B TEST PATTERNS
Bits[7:4]CH B GAIN: Channel B gain programmability
These bits set the gain programmability in 0.5-dB steps for channel B.
0000 = 0-dB gain (default after reset)
0001 = 0.5-dB gain
0010 = 1-dB gain
0011 = 1.5-dB gain
0100 = 2-dB gain
0101 = 2.5-dB gain
0110 = 3-dB gain
0111 = 3.5-dB gain
1000 = 4-dB gain
1001 = 4.5-dB gain
1010 = 5-dB gain
1011 = 5.5-dB gain
1100 = 6-dB gain
Bit 3Always write 0
Bits[2:0]CH B TEST PATTERNS: Channel B data capture
These bits verify data capture for channel B.
000 = Normal operation
001 = Outputs all 0s
010 = Outputs all 1s
011 = Outputs toggle pattern.
For the ADS424x, output data D[13:0] are an alternating sequence of 10101010101010 and 01010101010101.
For the ADS422x, the output data D[11:0] are an alternating sequence of 101010101010 and 010101010101.
100 = Outputs digital ramp.
For the ADS424x, output data increment by one LSB (14-bit) every clock cycle from code 0 to code 16383.
For the ADS422x, output data increment by one LSB (12-bit) every fourth clock cycle from code 0 to code 4095.
101 = Outputs custom pattern; use registers 3Fh and 40h to set the custom pattern
110 = Unused
111 = Unused
76543210
00ENABLE OFFSET CORR00000
Bits[7:6]Always write 0
Bit 5ENABLE OFFSET CORR: Offset correction setting
This bit enables the offset correction.
0 = Offset correction disabled
1 = Offset correction enabled
Bits[4:0]Always write 0
76543210
00CUSTOM PATTERN D13CUSTOM PATTERN D12CUSTOM PATTERN D11CUSTOM PATTERN D10CUSTOM PATTERN D9CUSTOM PATTERN D8
Bits[7:6]Always write 0
Bits[5:0]CUSTOM PATTERN D[13:8]
These are the six upper bits of the custom pattern available at the output instead of ADC data.
Note that for the ADS424x, the custom pattern is 14-bit. The ADS422x custom pattern is 12-bit.
76543210
CUSTOM PATTERN D7CUSTOM PATTERN D6CUSTOM PATTERN D5CUSTOM PATTERN D4CUSTOM PATTERN D3CUSTOM PATTERN D2CUSTOM PATTERN D1CUSTOM PATTERN D0
Bits[7:0]CUSTOM PATTERN D[7:0]
These are the eight upper bits of the custom pattern available at the output instead of ADC data.
Note that for the ADS424x, the custom pattern is 14-bit. The ADS422x custom pattern is 12-bit; use the CUSTOM PATTERN D[13:2] register bits.
76543210
LVDS CMOSCMOS CLKOUT STRENGTH00DIS OBUF
Bits[7:6]LVDS CMOS: Interface selection
These bits select the interface.
00 = DDR LVDS interface
01 = DDR LVDS interface
10 = DDR LVDS interface
11 = Parallel CMOS interface
Bits[5:4]CMOS CLKOUT STRENGTH
These bits control the strength of the CMOS output clock.
00 = Maximum strength (recommended)
01 = Medium strength
10 = Low strength
11 = Very low strength
Bits[3:2]Always write 0
Bits[1:0]DIS OBUF
These bits power down data and clock output buffers for both the CMOS and LVDS output interface. When powered down, the output buffers are in 3-state.
00 = Default
01 = Power-down data output buffers for channel B
10 = Power-down data output buffers for channel A
11 = Power-down data output buffers for both channels as well as the clock output buffer
76543210
CLKOUT FALL POSNCLKOUT RISE POSNEN DIGITAL000
Bits[7:6]CLKOUT FALL POSN
In LVDS mode:
00 = Default
01 = The falling edge of the output clock advances by 450 ps
10 = The falling edge of the output clock advances by 150 ps
11 = The falling edge of the output clock is delayed by 550 ps
In CMOS mode:
00 = Default
01 = The falling edge of the output clock is delayed by 150 ps
10 = Do not use
11 = The falling edge of the output clock advances by 100 ps
Bits[5:6]CLKOUT RISE POSN
In LVDS mode:
00 = Default
01 = The rising edge of the output clock advances by 450 ps
10 = The rising edge of the output clock advances by 150 ps
11 = The rising edge of the output clock is delayed by 250 ps
In CMOS mode:
00 = Default
01 = The rising edge of the output clock is delayed by 150 ps
10 = Do not use
11 = The rising edge of the output clock advances by 100 ps
Bit 3EN DIGITAL: Digital function enable
0 = All digital functions disabled
1 = All digital functions (such as test patterns, gain, and offset correction) enabled
Bits[2:0]Always write 0
76543210
STBYLVDS CLKOUT STRENGTHLVDS DATA STRENGTH00PDN GLOBAL00
Bit 7STBY: Standby setting
0 = Normal operation
1 = Both channels are put in standby; wakeup time from this mode is fast (typically 50 µs).
Bit 6LVDS CLKOUT STRENGTH: LVDS output clock buffer strength setting
0 = LVDS output clock buffer at default strength to be used with 100-Ω external termination
1 = LVDS output clock buffer has double strength to be used with 50-Ω external termination
Bit 5LVDS DATA STRENGTH
0 = All LVDS data buffers at default strength to be used with 100-Ω external termination
1 = All LVDS data buffers have double strength to be used with 50-Ω external termination
Bits[4:3]Always write 0
Bit 2PDN GLOBAL
0 = Normal operation
1 = Total power down; all ADC channels, internal references, and output buffers are powered down. Wakeup time from this mode is slow (typically 100 µs).
Bits[1:0]Always write 0
76543210
0000000HIGH FREQ MODE CH B
Bits[7:1]Always write 0
Bit 0HIGH FREQ MODE CH B: High-frequency mode for channel B
0 = Default
1 = Use this mode for high input frequencies
76543210
0000000HIGH FREQ MODE CH A
Bits[7:1]Always write 0
Bit 0HIGH FREQ MODE CH A: High-frequency mode for channel A
0 = Default
1 = Use this mode for high input frequencies
76543210
CH A OFFSET PEDESTAL00
Bits[7:2]CH A OFFSET PEDESTAL: Channel A offset pedestal selection
When the offset correction is enabled, the final converged value after the offset is corrected is the ADC midcode value. A pedestal can be added to the final converged value by programming these bits. See the Offset Correction section. Channels can be independently programmed for different offset pedestals by choosing the relevant register address.
For the ADS424x, the pedestal ranges from –32 to +31, so the output code can vary from midcode-32 to midcode+32 by adding pedestal D7-D2.
For the ADS422x, the pedestal ranges from –8 to +7, so the output code can vary from midcode-8 to midcode+7 by adding pedestal D7-D4.
ADS422x (Program Bits D[7:4])ADS424x (Program Bits D[7:2])
0111 = Midcode+7
0110 = Midcode+6
0101 = Midcode+5
…
0000 = Midcode
1111 = Midcode-1
1110 = Midcode-2
1101 = Midcode-3
…
1000 = Midcode-8		011111 = Midcode+31
011110 = Midcode+30
011101 = Midcode+29
…
000000 = Midcode
111111 = Midcode-1
111110 = Midcode-2
111101 = Midcode-3
…
100000 = Midcode-32
Bits[1:0]Always write 0
76543210
CH B OFFSET PEDESTAL00
Bits[7:2]CH B OFFSET PEDESTAL: Channel B offset pedestal selection
When offset correction is enabled, the final converged value after the offset is corrected is the ADC midcode value. A pedestal can be added to the final converged value by programming these bits; see the Offset Correction section. Channels can be independently programmed for different offset pedestals by choosing the relevant register address.
For the ADS424x, the pedestal ranges from –32 to +31, so the output code can vary from midcode-32 to midcode+32 by adding pedestal D[7:2]. For the ADS422x, the pedestal ranges from –8 to +7, so the output code can vary from midcode-8 to midcode+7 by adding pedestal D[7:4].
ADS422x (Program Bits D[7:4])ADS424x (Program Bits D[7:2])
0111 = Midcode+7
0110 = Midcode+6
0101 = Midcode+5
…
0000 = Midcode
1111 = Midcode-1
1110 = Midcode-2
1101 = Midcode-3
…
1000 = Midcode-8		011111 = Midcode+31
011110 = Midcode+30
011101 = Midcode+29
…
000000 = Midcode
111111 = Midcode-1
111110 = Midcode-2
111101 = Midcode-3
…
100000 = Midcode-32
Bits[1:0]Always write 0
76543210
FREEZE OFFSET CORR0OFFSET CORR TIME CONSTANT00
Bit 7FREEZE OFFSET CORR: Freeze offset correction setting
This bit sets the freeze offset correction estimation.
0 = Estimation of offset correction is not frozen (the EN OFFSET CORR bit must be set)
1 = Estimation of offset correction is frozen (the EN OFFSET CORR bit must be set); when frozen, the last estimated value is used for offset correction of every clock cycle. See the Offset Correction section.
Bit 6Always write 0
Bits[5:2]OFFSET CORR TIME CONSTANT
The offset correction loop time constant in number of clock cycles. Refer to the Offset Correction section.
Bits[1:0]Always write 0
76543210
0000000LOW SPEED MODE CH B
Bits[7:1]Always write 0
Bit 0LOW SPEED MODE CH B: Channel B low-speed mode enable
This bit enables the low-speed mode for channel B. Set the EN LOW SPEED MODE bit to 1 before using this bit.
0 = Low-speed mode is disabled for channel B
1 = Low-speed mode is enabled for channel B
76543210
000EN LOW SPEED MODE0000
Bits[7:5]Always write 0
Bit 4EN LOW SPEED MODE: Enable control of low-speed mode through serial register bits (ADS42x5 and ADS42x6 only)
This bit enables the control of the low-speed mode using the LOW SPEED MODE CH B and LOW SPEED MODE CH A register bits.
0 = Low-speed mode is disabled
1 = Low-speed mode is controlled by serial register bits
Bits[3:0]Always write 0
76543210
000000EN LVDS SWING
Bits[7:2]Always write 0
Bits[1:0]EN LVDS SWING: LVDS swing enable
These bits enable LVDS swing control using the LVDS SWING register bits.
00 = LVDS swing control using the LVDS SWING register bits is disabled
01 = Do not use
10 = Do not use
11 = LVDS swing control using the LVDS SWING register bits is enabled
76543210
0000LOW SPEED MODE CH A000
Bits[7:4]Always write 0
Bit 3LOW SPEED MODE CH A: Channel A low-speed mode enable
This bit enables the low-speed mode for channel A. Set the EN LOW SPEED MODE bit to 1 before using this bit.
0 = Low-speed mode is disabled for channel A
1 = Low-speed mode is enabled for channel A
Bits[2:0]Always write 0