SBAS673A July   2014  – October 2015 ADC3421 , ADC3422 , ADC3423 , ADC3424

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
  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: General
    6. 7.6  Electrical Characteristics: ADC3421, ADC3422
    7. 7.7  Electrical Characteristics: ADC3423, ADC3424
    8. 7.8  AC Performance: ADC3421
    9. 7.9  AC Performance: ADC3422
    10. 7.10 AC Performance: ADC3423
    11. 7.11 AC Performance: ADC3424
    12. 7.12 Digital Characteristics
    13. 7.13 Timing Requirements: General
    14. 7.14 Timing Requirements: LVDS Output
    15. 7.15 Typical Characteristics: ADC3421
    16. 7.16 Typical Characteristics: ADC3422
    17. 7.17 Typical Characteristics: ADC3423
    18. 7.18 Typical Characteristics: ADC3424
    19. 7.19 Typical Characteristics: Common
    20. 7.20 Typical Characteristics: Contour
  8. Parameter Measurement Information
    1. 8.1 Timing Diagrams
  9. Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Analog Inputs
      2. 9.3.2 Clock Input
        1. 9.3.2.1 SNR and Clock Jitter
      3. 9.3.3 Digital Output Interface
        1. 9.3.3.1 One-Wire Interface: 12x Serialization
        2. 9.3.3.2 Two-Wire Interface: 6x Serialization
    4. 9.4 Device Functional Modes
      1. 9.4.1 Input Clock Divider
      2. 9.4.2 Chopper Functionality
      3. 9.4.3 Power-Down Control
      4. 9.4.4 Internal Dither Algorithm
      5. 9.4.5 Summary of Performance Mode Registers
    5. 9.5 Programming
      1. 9.5.1 Serial Interface
        1. 9.5.1.1 Register Initialization
          1. 9.5.1.1.1 Serial Register Write
          2. 9.5.1.1.2 Serial Register Readout
      2. 9.5.2 Register Initialization
    6. 9.6 Register Maps
      1. 9.6.1 Serial Register Description
        1. 9.6.1.1 Register 13h (address = 13h)
        2. 9.6.1.2 Register 11Dh (address = 11Dh)
        3. 9.6.1.3 Register 21Dh (address = 21Dh)
        4. 9.6.1.4 Register 308h (address = 308h)
        5. 9.6.1.5 Register 41Dh (address = 41Dh)
        6. 9.6.1.6 Register 51Dh (address = 51Dh)
        7. 9.6.1.7 Register 608h (address = 608h)
        8. 9.6.1.8 Register 70Ah (address = 70Ah)
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Applications
      1. 10.2.1 Driving Circuit Design: Low Input Frequencies
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curve
      2. 10.2.2 Driving Circuit Design: Input Frequencies Between 100 MHz to 230 MHz
        1. 10.2.2.1 Design Requirements
        2. 10.2.2.2 Detailed Design Procedure
        3. 10.2.2.3 Application Curve
      3. 10.2.3 Driving Circuit Design: Input Frequencies Greater than 230 MHz
        1. 10.2.3.1 Design Requirements
        2. 10.2.3.2 Detailed Design Procedure
        3. 10.2.3.3 Application Curve
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Related Links
    2. 13.2 Community Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

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9 Detailed Description

9.1 Overview

The ADC342x are a high-linearity, ultra-low power, quad-channel, 12-bit, 25-MSPS to 125-MSPS, analog-to-digital converter (ADC) family. The devices are designed specifically to support demanding, high input frequency signals with large dynamic range requirements. An input clock divider allows more flexibility for system clock architecture design and the SYSREF input enables complete system synchronization. The ADC342x family supports a serial low-voltage differential signaling (LVDS) interface in order to reduce the number of interface lines, thus allowing for high system integration density. The serial LVDS interface is two-wire, where each ADC data are serialized and output over two LVDS pairs. An internal phase-locked loop (PLL) multiplies the incoming ADC sampling clock to derive the bit clock that is used to serialize the 12-bit output data from each channel. In addition to the serial data streams, the frame and bit clocks are also transmitted as LVDS outputs.

9.2 Functional Block Diagram

ADC3421 ADC3422 ADC3423 ADC3424 fbd_sbas673.gif

9.3 Feature Description

9.3.1 Analog Inputs

The ADC342x analog signal inputs are designed to be driven differentially. Each input pin (INP, INM) must swing symmetrically between (VCM + 0.5 V) and (VCM – 0.5 V), resulting in a 2-VPP (default) differential input swing. The input sampling circuit has a 3-dB bandwidth that extends up to 540 MHz (50-Ω source driving 50-Ω termination between INP and INM).

9.3.2 Clock Input

The device clock inputs can be driven differentially (sine, LVPECL, or LVDS) or single-ended (LVCMOS), with little or no difference in performance between them. The common-mode voltage of the clock inputs is set to 0.95 V using internal 5-kΩ resistors. The self-bias clock inputs of the ADC342x can be driven by the transformer-coupled, sine-wave clock source or by the ac-coupled, LVPECL and LVDS clock sources, as shown in Figure 132, Figure 133, and Figure 134. See Figure 135 for details regarding the internal clock buffer.

ADC3421 ADC3422 ADC3423 ADC3424 ai_dif_sinewave_clk_bas550.gif
NOTE: RT = termination resistor, if necessary.
Figure 132. Differential Sine-Wave Clock Driving Circuit
ADC3421 ADC3422 ADC3423 ADC3424 ai_lvds_clk_drv_bas550.gif Figure 133. LVDS Clock Driving Circuit
ADC3421 ADC3422 ADC3423 ADC3424 ai_lvpecl_clk_drv_bas550.gif Figure 134. LVPECL Clock Driving Circuit
ADC3421 ADC3422 ADC3423 ADC3424 ai_intclk_buffer_sbas670.gif
NOTE: CEQ is 1 pF to 3 pF and is the equivalent input capacitance of the clock buffer.
Figure 135. Internal Clock Buffer

A single-ended CMOS clock can be ac-coupled to the CLKP input, with CLKM connected to ground with a 0.1-μF capacitor, as shown in Figure 136. However, for best performance the clock inputs must be driven differentially, thereby reducing susceptibility to common-mode noise. For high input frequency sampling, TI recommends using a clock source with very low jitter. Band-pass filtering of the clock source can help reduce the effects of jitter. There is no change in performance with a non-50% duty cycle clock input.

ADC3421 ADC3422 ADC3423 ADC3424 ai_drv_cir_1end_las900.gif Figure 136. Single-Ended Clock Driving Circuit

9.3.2.1 SNR and Clock Jitter

The signal-to-noise ratio of the ADC is limited by three different factors, as shown in Equation 1. Quantization noise (typically 74 dB for a 12-bit ADC) and thermal noise limit SNR at low input frequencies, and the clock jitter sets SNR for higher input frequencies.

Equation 1. ADC3421 ADC3422 ADC3423 ADC3424 Eq_SNR_CLKJttr_BAS663.gif

The SNR limitation resulting from sample clock jitter can be calculated with Equation 2.

Equation 2. ADC3421 ADC3422 ADC3423 ADC3424 Eq_SNR_Lmtn_BAS663.gif

The total clock jitter (TJitter) has two components: the internal aperture jitter (130 fs for the device) which is set by the noise of the clock input buffer and the external clock. TJitter can be calculated with Equation 3.

Equation 3. ADC3421 ADC3422 ADC3423 ADC3424 Eq_Ttl_Clk_Jttr_BAS663.gif

External clock jitter can be minimized by using high-quality clock sources and jitter cleaners as well as band-pass filters at the clock input; a faster clock slew rate improves the ADC aperture jitter. The devices have a typical thermal noise of 72.7 dBFS and internal aperture jitter of 130 fs. The SNR, depending on the amount of external jitter for different input frequencies, is shown in Figure 137.

ADC3421 ADC3422 ADC3423 ADC3424 D036_SBAS673.gif Figure 137. SNR vs Frequency for Different Clock Jitter

9.3.3 Digital Output Interface

The devices offer two different output format options, thus making interfacing to a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC) easy. Each option can be easily programmed using the serial interface, as shown in Table 3. The output interface options are:

  • One-wire, 1x frame clock, 12x serialization with the DDR bit clock and
  • Two-wire, 1x frame clock, 6x serialization with the DDR bit clock.

Table 3. Interface Rates

INTERFACE OPTIONS SERIALIZATION RECOMMENDED SAMPLING FREQUENCY (MSPS) BIT CLOCK FREQUENCY (MHz) FRAME CLOCK FREQUENCY (MHz) SERIAL DATA RATE PER WIRE (Mbps)
MINIMUM MAXIMUM
One-wire 12x 15 90 15 180
80 480 80 960
Two-wire
(Default after Reset)
6x 20(1) 60 20 120
125 375 125 750
(1) Use the LOW SPEED ENABLE register bits for low speed operation; see Table 21.

9.3.3.1 One-Wire Interface: 12x Serialization

In this interface option, the device outputs the data of each ADC serially on a single LVDS pair (one-wire). The data are available at the rising and falling edges of the bit clock (DDR bit clock). The ADC outputs a new word at the rising edge of every frame clock, starting with the LSB. The data rate is 12x sample frequency (12x serialization).

9.3.3.2 Two-Wire Interface: 6x Serialization

The two-wire interface is recommended for sampling frequencies above 65 MSPS. The output data rate is 6x sample frequency because six data bits are output every clock cycle on each differential pair. Each ADC sample is sent over the two wires with the six MSBs on Dx1P, Dx1M and the six LSBs on Dx0P, Dx0M, as shown in Figure 138.

ADC3421 ADC3422 ADC3423 ADC3424 opt_tmng_dgrm_sbas673.gif Figure 138. Output Timing Diagram

9.4 Device Functional Modes

9.4.1 Input Clock Divider

The devices are equipped with an internal divider on the clock input. The clock divider allows operation with a faster input clock, thus simplifying the system clock distribution design. The clock divider can be bypassed for operation with a 125-MHz clock and the divide-by-2 option supports a maximum input clock of 250 MHz and the divide-by-4 option provides a maximum input clock frequency of 500 MHz.

9.4.2 Chopper Functionality

The devices are equipped with an internal chopper front-end. Enabling the chopper function swaps the ADC noise spectrum by shifting the 1/f noise from dc to fS / 2. Figure 139 shows the noise spectrum with the chopper off and Figure 140 shows the noise spectrum with the chopper on. This function is especially useful in applications requiring good ac performance at low input frequencies or in dc-coupled applications. The chopper can be enabled via SPI register writes and is recommended for input frequencies below 30 MHz. The chopper function creates a spur at fS / 2 that must be filtered out digitally.

ADC3421 ADC3422 ADC3423 ADC3424 D016_SBAS672.gif
fS = 125 MSPS, SNR = 70.4 dBFS,
fIN = 10 MHz, SFDR = 98 dBc
Figure 139. Chopper Off
ADC3421 ADC3422 ADC3423 ADC3424 D017_SBAS672.gif
fS = 125 MSPS, SNR = 70.4 dBFS,
fIN = 10 MHz, SFDR = 97 dBc
Figure 140. Chopper On

9.4.3 Power-Down Control

The power-down functions of the ADC342x can be controlled either through the parallel control pin (PDN) or through an SPI register setting (see register 15h). The PDN pin can also be configured via SPI to a global power-down or standby functionality, as shown in Table 4.

Table 4. Power-Down Modes

FUNCTION POWER CONSUMPTION (mW) WAKE-UP TIME (µs)
Global power-down 5 85
Standby 45 35

9.4.4 Internal Dither Algorithm

The ADC342x use an internal dither algorithm to achieve high SFDR and a clean spectrum. However, the dither algorithm marginally degrades SNR, creating a trade-off between SNR and SFDR. If desired, the dither algorithm can be turned off by using the DIS DITH CHx registers bits. Figure 141 and Figure 142 show the effect of using dither algorithms.

ADC3421 ADC3422 ADC3423 ADC3424 D201_SBAS673.gif
SFDR = 95 dBc, SNR = 70.4 dBFS, SINAD = 70.4 dBFS,
THD = 98 dBc, HD2 = 95 dBc, HD3 = 97 dBc
Figure 141. FFT for 10-MHz Input Signal
(Chopper On, Dither On)
ADC3421 ADC3422 ADC3423 ADC3424 D202_SBAS673.gif
SFDR = 91 dBc, SNR = 70.7 dBFS, SINAD = 70.6 dBFS,
THD = 86 dBc, HD2 = 92 dBc, HD3 = 91 dBc
Figure 142. FFT for 10-MHz Input Signal
(Chopper On, Dither Off)

9.4.5 Summary of Performance Mode Registers

Table 5 lists the location, value, and functions of performance mode registers in the device.

Table 5. Performance Modes

MODE REGISTER SETTINGS DESCRIPTION
Special modes Registers 139 (bit 3), 239 (bit 3), 439 (bit 3), and 539 (bit 3) Always write 1 for best performance
Disable dither Registers 1 (bits 7:0), 134 (bits 5 and 3), 234 (bits 5 and 3),
434 (bits 5 and 3), and 534 (bits 5 and 3)
Disable dither to improve SNR
Disable chopper Registers 122 (bit 1), 222 (bit 1), 422 (bit 1), and 522 (bit 1) Disable chopper (shifts 1/f noise floor at dc)
High IF modes Registers 11Dh (bit 1), 21Dh (bit 1), 41Dh (bit 1), 51Dh (bit 1), 308h (bits 7-6) and 608h (bits 7-6) Improves HD3 by a couple of dB for IF > 100 MHz

9.5 Programming

The ADC342x can be configured using a serial programming interface, as described in this section.

9.5.1 Serial Interface

The device has a set of internal registers that can be accessed by the serial interface formed by the SEN (serial interface enable), SCLK (serial interface clock), SDATA (serial interface data), and SDOUT (serial interface data output) pins. Serially shifting bits into the device is enabled when SEN is low. Serial data SDATA are latched at every SCLK rising edge when SEN is active (low). The serial data are loaded into the register at every 24th SCLK rising edge when SEN is low. When the word length exceeds a multiple of 24 bits, the excess bits are ignored. Data can be loaded in multiples of 24-bit words within a single active SEN pulse. The interface can function with SCLK frequencies from 20 MHz down to very low speeds (of a few hertz) and also with a non-50% SCLK duty cycle.

9.5.1.1 Register Initialization

After power-up, the internal registers must be initialized to their default values through a hardware reset by applying a high pulse on the RESET pin (of durations greater than 10 ns), as shown in Figure 143. If required, the serial interface registers can be cleared during operation either:

  1. Through a hardware reset, or
  2. By applying a software reset. When using the serial interface, set the RESET bit (D0 in register address 06h) 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.

9.5.1.1.1 Serial Register Write

The device internal register can be programmed with these steps:

  1. Drive the SEN pin low,
  2. Set the R/W bit to 0 (bit A15 of the 16-bit address),
  3. Set bit A14 in the address field to 1,
  4. Initiate a serial interface cycle by specifying the address of the register (A13 to A0) whose content must be written, and
  5. Write the 8-bit data that are latched in on the SCLK rising edge.

Figure 143 and Table 6 show the timing requirements for the serial register write operation.

ADC3421 ADC3422 ADC3423 ADC3424 Srl_Rgstr_wrt_Tmg_BAS663.gif Figure 143. Serial Register Write Timing Diagram

Table 6. Serial Interface Timing(1)

MIN TYP MAX UNIT
fSCLK SCLK frequency (equal to 1 / tSCLK) > dc 20 MHz
tSLOADS SEN to SCLK setup time 25 ns
tSLOADH SCLK to SEN hold time 25 ns
tDSU SDIO setup time 25 ns
tDH SDIO hold time 25 ns
(1) Typical values are at 25°C, full temperature range is from TMIN = –40°C to TMAX = 85°C, and AVDD = DVDD = 1.8 V, unless otherwise noted.

9.5.1.1.2 Serial Register Readout

The device includes a mode where the contents of the internal registers can be read back using the SDOUT pin. This readback mode may be useful as a diagnostic check to verify the serial interface communication between the external controller and the ADC. The procedure to read the contents of the serial registers is as follows:

  1. Drive the SEN pin low.
  2. Set the R/W bit (A15) to 1. This setting disables any further writes to the registers.
  3. Set bit A14 in the address field to 1.
  4. Initiate a serial interface cycle specifying the address of the register (A13 to A0) whose content must be read.
  5. The device outputs the contents (D7 to D0) of the selected register on the SDOUT pin.
  6. The external controller can latch the contents at the SCLK rising edge.
  7. To enable register writes, reset the R/W register bit to 0.

When READOUT is disabled, the SDOUT pin is in a high-impedance mode. If serial readout is not used, the SDOUT pin must float. Figure 144 shows a timing diagram of the serial register read operation. Data appear on the SDOUT pin at the SCLK falling edge with an approximate delay (tSD_DELAY) of 20 ns, as shown in Figure 145.

ADC3421 ADC3422 ADC3423 ADC3424 Srl_Rgstr_Rd_Tmg_BAS663.gif Figure 144. Serial Register Read Timing Diagram
ADC3421 ADC3422 ADC3423 ADC3424 ai_tim_sdout_las900.gif Figure 145. SDOUT Timing Diagram

9.5.2 Register Initialization

After power-up, the internal registers must be initialized to their default values through a hardware reset by applying a high pulse on the RESET pin, as shown in Figure 146 and Table 7.

ADC3421 ADC3422 ADC3423 ADC3424 Rgstr_Intlztn_BAS663.gif Figure 146. Initialization of Serial Registers after Power-Up

Table 7. Power-Up Timing

MIN TYP MAX UNIT
t1 Power-on delay from power-up to active high RESET pulse 1 ms
t2 Reset pulse duration: active high RESET pulse duration 10 ns
t3 Register write delay from RESET disable to SEN active 100 ns

If required, the serial interface registers can be cleared during operation either:

  1. Through hardware reset, or
  2. By applying a software reset. When using the serial interface, set the RESET bit (D0 in register address 06h) 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.

9.6 Register Maps

Table 8. Register Map Summary

REGISTER ADDRESS, A[13:0] (Hex) REGISTER DATA
7 6 5 4 3 2 1 0
Register 01h DIS DITH CHA DIS DITH CHB DIS DITH CHC DIS DITH CHD
Register 03h 0 0 0 0 0 0 0 ODD EVEN
Register 04h 0 0 0 0 0 0 0 FLIP WIRE
Register 05h 0 0 0 0 0 0 0 1W-2W
Register 06h 0 0 0 0 0 0 TEST PATTERN EN RESET
Register 07h 0 0 0 0 0 0 0 OVR ON LSB
Register 09h 0 0 0 0 0 0 ALIGN TEST PATTERN DATA FORMAT
Register 0Ah CHA TEST PATTERN CHB TEST PATTERN
Register 0Bh CHC TEST PATTERN 0 CHD TEST PATTERN
Register 0Eh CUSTOM PATTERN[11:4]
Register 0Fh CUSTOM PATTERN[3:0] 0 0 0 0
Register 13h 0 0 0 0 0 0 LOW SPEED ENABLE
Register 15h CHA PDN CHB PDN CHC PDN CHD PDN STANDBY GLOBAL PDN 0 CONFIG PDN PIN
Register 25h LVDS SWING
Register 27h CLK DIV 0 0 0 0 0 0
Register 11Dh 0 0 0 0 0 0 HIGH IF MODE0 0
Register 122h 0 0 0 0 0 0 DIS CHOP CHA 0
Register 134h 0 0 DIS DITH CHA 0 DIS DITH CHA 0 0 0
Register 139h 0 0 0 0 SP1 CHA 0 0 0
Register 21Dh 0 0 0 0 0 0 HIGH IF MODE1 0
Register 222h 0 0 0 0 0 0 DIS CHOP CHD 0
Register 234h 0 0 DIS DITH CHD 0 DIS DITH CHD 0 0 0
Register 239h 0 0 0 0 SP1 CHD 0 0 0
Register 308 HIGH IF MODE <5:4> 0 0 0 0 0 0
Register 41Dh 0 0 0 0 0 0 HIGH IF MODE2 0
Register 422h 0 0 0 0 0 0 DIS CHOP CHB 0
Register 434h 0 0 DIS DITH CHB 0 DIS DITH CHB 0 0 0
Register 439h 0 0 0 0 SP1 CHB 0 0 0
Register 51Dh 0 0 0 0 0 0 HIGH IF MODE3 0
Register 522h 0 0 0 0 0 0 DIS CHOP CHC 0
Register 534h 0 0 DIS DITH CHC 0 DIS DITH CHC 0 0 0
Register 539h 0 0 0 0 SP1 CHC 0 0 0
Register 608h HIGH IF MODE <7:6> 0 0 0 0 0 0
Register 70Ah 0 0 0 0 0 0 0 PDN SYSREF

9.6.1 Serial Register Description

Register 01h (address = 01h)

Figure 147. Register 01h
7 6 5 4 3 2 1 0
DIS DITH CHA DIS DITH CHB DIS DITH CHC DIS DITH CHD
R/W-0h R/W-0h R/W-0h R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset

Table 9. Register 01h Field Descriptions

Bit Field Type Reset Description
7-6 DIS DITH CHA R/W 0h These bits enable or disable the on-chip dither. Control this bit along with bits 5 and 3 of register 134h.
00 = Default
11 = Dither is disabled for channel A. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
5-4 DIS DITH CHB R/W 0h These bits enable or disable the on-chip dither. Control this bit along with bits 5 and 3 of register 434h.
00 = Default
11 = Dither is disabled for channel B. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
3-2 DIS DITH CHC R/W 0h These bits enable or disable the on-chip dither. Control this bit along with bits 5 and 3 of register 534h.
00 = Default
11 = Dither is disabled for channel B. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
1-0 DIS DITH CHD R/W 0h These bits enable or disable the on-chip dither. Control this bit along with bits 5 and 3 of register 234h.
00 = Default
11 = Dither is disabled for channel B. In this mode, SNR typically improves by 0.2 dB at 70 MHz.

Register 03h (address = 03h)

Figure 148. Register 03h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 ODD EVEN
W-0h W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 10. Register 03h Field Descriptions

Bit Field Type Reset Description
7-6 0 W 0h Must write 0.
0 ODD EVEN R/W 0h This bit selects the bit sequence on the output wires (in 2-wire mode only).
0 = Bits 0, 1, 2, and so forth appear on wire-0; bits 7, 8, 9, and so forth appear on wire-1.
1 = Bits 0, 2, 4, and so forth appear on wire-0; bits 1, 3, 5, and so forth appear on wire-1.

Register 04h (address = 04h)

Figure 149. Register 04h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 FLIP WIRE
W-0h W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 11. Register 04h Field Descriptions

Bit Field Type Reset Description
7-1 0 W 0h Must write 0.
0 FLIP WIRE R/W 0h This bit flips the data on the output wires. Valid only in two wire configuration.
0 = Default
1 = Data on output wires is flipped. Pin D0x becomes D1x, and vice versa.

Register 05h (address = 05h)

Figure 150. Register 05h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 1W-2W
W-0h W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 12. Register 05h Field Descriptions

Bit Field Type Reset Description
7-1 0 W 0h Must write 0.
0 1W-2W R/W 0h This bit transmits output data on either one or two wires.
0 = Output data are transmitted on two wires (Dx0P, Dx0M and Dx1P, Dx1M)
1 = Output data are transmitted on one wire (Dx0P, Dx0M). In this mode, the recommended fS is less than 80 MSPS.

Register 06h (address = 06h)

Figure 151. Register 06h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 TEST PATTERN EN RESET
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 13. Register 06h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 TEST PATTERN EN R/W 0h This bit enables test pattern selection for the digital outputs.
0 = Normal output
1 = Test pattern output enabled
0 RESET R/W 0h This bit applies a software reset.
This bit resets all internal registers to the default values and self-clears to 0.

Register 07h (address = 07h)

Figure 152. Register 07h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 OVR ON LSB
W-0h W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 14. Register 07h Field Descriptions

Bit Field Type Reset Description
7-1 0 W 0h Must write 0.
0 OVR ON LSB R/W 0h This bit provides OVR information on the LSB bits.
0 = Output data bit 0 functions as the LSB of the 12-bit data
1 = Output data bit 0 carries the overrange (OVR) information

Register 09h (address = 09h)

Figure 153. Register 09h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 ALIGN TEST PATTERN DATA FORMAT
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 15. Register 09h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 ALIGN TEST PATTERN R/W 0h This bit aligns the test patterns across the outputs of both channels.
0 = Test patterns of both channels are free running
1 = Test patterns of both channels are aligned
0 DATA FORMAT R/W 0h This bit selects th digital output data format.
0 = Twos complement
1 = Offset binary

Register 0Ah (address = 0Ah)

Figure 154. Register 0Ah
7 6 5 4 3 2 1 0
CHA TEST PATTERN CHB TEST PATTERN
R/W-0h R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset

Table 16. Register 0Ah Field Descriptions

Bit Field Type Reset Description
7-4 CHA TEST PATTERN R/W 0h These bits control the test pattern for channel A after the TEST PATTERN EN bit is set.
0000 = Normal operation
0001 = All 0's
0010 = All 1's
0011 = Toggle pattern: data alternate between 101010101010 and 010101010101
0100 = Digital ramp: data increment by 1 LSB every clock cycle from code 0 to 4095
0101 = Custom pattern: output data are the same as programmed by the CUSTOM PATTERN register bits
0110 = Deskew pattern: data are AAAh
1000 = PRBS pattern: data are a sequence of pseudo random numbers
1001 = 8-point sine-wave: data are a repetitive sequence of the following eight numbers that form a sine-wave: 0, 599, 2048, 3496, 4095, 3496, 2048, and 599
Others = Do not use
3-0 CHB TEST PATTERN R/W 0h These bits control the test pattern for channel B after the TEST PATTERN EN bit is set.
0000 = Normal operation
0001 = All 0's
0010 = All 1's
0011 = Toggle pattern: data alternate between 101010101010 and 010101010101
0100 = Digital ramp: data increment by 1 LSB every clock cycle from code 0 to 4095
0101 = Custom pattern: output data are the same as programmed by the CUSTOM PATTERN register bits
0110 = Deskew pattern: data are AAAh
1000 = PRBS pattern: data are a sequence of pseudo random numbers
1001 = 8-point sine-wave: data are a repetitive sequence of the following eight numbers that form a sine-wave: 0, 599, 2048, 3496, 4095, 3496, 2048, and 599
Others = Do not use

Register 0Bh (address = 0Bh)

Figure 155. Register 0Bh
7 6 5 4 3 2 1 0
CHC TEST PATTERN CHD TEST PATTERN
R/W-0h R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset

Table 17. Register 0Bh Field Descriptions

Bit Field Type Reset Description
7-4 CHC TEST PATTERN R/W 0h These bits control the test pattern for channel C after the TEST PATTERN EN bit is set.
0000 = Normal operation
0001 = All 0's
0010 = All 1's
0011 = Toggle pattern: data alternate between 101010101010 and 010101010101.
0100 = Digital ramp: data increment by 1 LSB every clock cycle from code 0 to 4095.
0110 = Custom pattern: output data are the same as programmed by the CUSTOM PATTERN register bits.
1000 = Deskew pattern: data are AAAh.
1010 = PRBS pattern: data are a sequence of pseudo random numbers.
1011 = 8-point sine wave: data are a repetitive sequence of the following eight numbers that form a sine-wave: 0, 599, 2048, 3496, 4095, 3496, 2048, 599.
Others = Do not use
3-0 CHD TEST PATTERN R/W 0h These bits control the test pattern for channel D after the TEST PATTERN EN bit is set.
0000 = Normal operation
0001 = All 0's
0010 = All 1's
0011 = Toggle pattern: data alternate between 101010101010 and 010101010101.
0100 = Digital ramp: data increment by 1 LSB every clock cycle from code 0 to 4095.
0110 = Custom pattern: output data are the same as programmed by the CUSTOM PATTERN register bits.
1000 = Deskew pattern: data are AAAh.
1010 = PRBS pattern: data are a sequence of pseudo random numbers.
1011 = 8-point sine wave: data are a repetitive sequence of the following eight numbers that form a sine-wave: 0, 599, 2048, 3496, 4095, 3496, 2048, 599.
Others = Do not use

Register 0Eh (address = 0Eh)

Figure 156. Register 0Eh
7 6 5 4 3 2 1 0
CUSTOM PATTERN[11:4]
R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset

Table 18. Register 0Eh Field Descriptions

Bit Field Type Reset Description
7-0 CUSTOM PATTERN[11:4] R/W 0h These bits set the 12-bit custom pattern (bits 11-4) for all channels.

Register 0Fh (address = 0Fh)

Figure 157. Register 0Fh
7 6 5 4 3 2 1 0
CUSTOM PATTERN[3:0] 0 0 0 0
R/W-0h W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 19. Register 0Fh Field Descriptions

Bit Field Type Reset Description
7-4 CUSTOM PATTERN[3:0] R/W 0h These bits set the 12-bit custom pattern (bits 3-0) for all channels.
3-0 0 W 0h Must write 0.

9.6.1.1 Register 13h (address = 13h)

Figure 158. Register 13h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 LOW SPEED ENABLE
W-0h R/W-0h R/W-0h W-0h R/W-0h R/W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 20. Register 13h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1-0 LOW SPEED ENABLE R/W 0h Enables low speed operation in 1-wire and 2-wire mode.
Depending upon sampling frequency, write this bit as per Table 21.

Table 21. LOW SPEED ENABLE Register Settings Across fS

fS, MSPS REGISTER BIT LOW SPEED ENABLE
MIN MAX 1-WIRE MODE 2-WIRE MODE
25 125 00 00
20 25 10 11
15 20 10 Not supported

Register 15h (address = 15h)

Figure 159. Register 15h
7 6 5 4 3 2 1 0
CHA PDN CHB PDN CHC PDN CHD PDN STANDBY GLOBAL PDN 0 CONFIG PDN PIN
W-0h R/W-0h R/W-0h W-0h R/W-0h R/W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 22. Register 15h Field Descriptions

Bit Field Type Reset Description
7 CHA PDN W 0h 0 = Normal operation
1 = Power-down channel A
6 CHB PDN R/W 0h 0 = Normal operation
1 = Power-down channel B
5 CHC PDN R/W 0h 0 = Normal operation
1 = Power-down channel C
4 CHD PDN W 0h 0 = Normal operation
1 = Power-down channel D
3 STANDBY R/W 0h The ADCs of both channels enter standby.
0 = Normal operation
1 = Standby
2 GLOBAL PDN R/W 0h 0 = Normal operation
1 = Global power-down
1 0 W 0h Must write 0.
0 CONFIG PDN PIN R/W 0h This bit configures the PDN pin as either a global power-down or standby pin.
0 = Logic high voltage on the PDN pin sends the device into global power-down
1 = Logic high voltage on the PDN pin sends the device into standby

Register 25h (address = 25h)

Figure 160. Register 25h
7 6 5 4 3 2 1 0
LVDS SWING
R/W-0h
LEGEND: R/W = Read/Write; -n = value after reset

Table 23. Register 25h Field Descriptions

Bit Field Type Reset Description
7-0 LVDS SWING R/W 0h These bits control the swing of the LVDS outputs (including the data output, bit clock, and frame clock).

Register 27h (address = 27h)

Figure 161. Register 27h
7 6 5 4 3 2 1 0
CLK DIV 0 0 0 0 0 0
R/W-0h W-0h W-0h W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 24. Register 27h Field Descriptions

Bit Field Type Reset Description
7-6 CLK DIV R/W 0h These bits select the internal clock divider for the input sampling clock.
00 = Divide-by-1
01 = Divide-by-1
10 = Divide-by-2
11 = Divide-by-4
5-0 0 W 0h Must write 0.

9.6.1.2 Register 11Dh (address = 11Dh)

Figure 162. Register 11Dh
7 6 5 4 3 2 1 0
0 0 0 0 0 0 HIGH IF MODE0 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 25. Register 11Dh Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 HIGH IF MODE0 Set the HIGH IF MODE[7:0] bits together to 1111.
Improves HD3 by a couple of dB for IF > 100 MHz.
0 0 W 0h Must write 0.

Register 122h (address = 122h)

Figure 163. Register 122h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 DIS CHOP CHA 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 26. Register 122h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 DIS CHOP CHA R/W 0h This bit disables the chopper.
Set this bit to shift the 1/f noise floor at dc.
0 = 1/f noise floor is centered at fS / 2 (default)
1 = Chopper mechanism is disabled; 1/f noise floor is centered at dc
0 0 W 0h Must write 0.

Register 134h (address = 134h)

Figure 164. Register 134h
7 6 5 4 3 2 1 0
0 0 DIS DITH CHA 0 DIS DITH CHA 0 0 0
W-0h W-0h R/W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 27. Register 134h Field Descriptions

Bit Field Type Reset Description
7-6 0 W 0h Must write 0.
5 DIS DITH CHA R/W 0h Set this bit along with bits 7 and 6 of register 01h.
00 = Default
11 = Dither is disabled for channel A. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
4 0 W 0h Must write 0.
3 DIS DITH CHA R/W 0h Set this bit along with bits 7 and 6 of register 01h.
00 = Default
11 = Dither is disabled for channel A. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
2-0 0 W 0h Must write 0.

Register 139h (address = 139h)

Figure 165. Register 139h
7 6 5 4 3 2 1 0
0 0 0 0 SP1 CHA 0 0 0
W-0h W-0h W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 28. Register 139h Field Descriptions

Bit Field Type Reset Description
7-4 0 W 0h Must write 0.
3 SP1 CHA R/W 0h This bit sets the special mode for best performance on channel A.
Always write 1 after reset.
2-0 0 W 0h Must write 0.

9.6.1.3 Register 21Dh (address = 21Dh)

Figure 166. Register 21Dh
7 6 5 4 3 2 1 0
0 0 0 0 0 0 HIGH IF MODE1 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 29. Register 21Dh Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 HIGH IF MODE1 R/W 0h Set the HIGH IF MODE[7:0] bits together to 1111.
Improves HD3 by a couple of dB for IF > 100 MHz.
0 0 W 0h Must write 0.

Register 222h (address = 222h)

Figure 167. Register 222h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 DIS CHOP CHD 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 30. Register 222h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 DIS CHOP CHD R/W 0h This bit disables the chopper.
Set this bit to shift the 1/f noise floor at dc.
0 = 1/f noise floor is centered at fS / 2 (default)
1 = Chopper mechanism is disabled; 1/f noise floor is centered at dc
0 0 W 0h Must write 0.

Register 234h (address = 234h)

Figure 168. Register 234h
7 6 5 4 3 2 1 0
0 0 DIS DITH CHD 0 DIS DITH CHD 0 0 0
W-0h W-0h R/W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 31. Register 234h Field Descriptions

Bit Field Type Reset Description
7-6 0 W 0h Must write 0.
5 DIS DITH CHD R/W 0h Set this bit with bits 1 and 0 of register 01h.
00 = Default
11 = Dither is disabled for channel D. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
4 0 W 0h Must write 0.
3 DIS DITH CHD R/W 0h Set this bit with bits 1 and 0 of register 01h.
00 = Default
11 = Dither is disabled for channel D. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
2-0 0 W 0h Must write 0.

Register 239h (address = 239h)

Figure 169. Register 239h
7 6 5 4 3 2 1 0
0 0 0 0 SP1 CHD 0 0 0
W-0h W-0h W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 32. Register 239h Field Descriptions

Bit Field Type Reset Description
7-4 0 W 0h Must write 0.
3 SP1 CHD R/W 0h This bit sets the special mode for best performance on channel D.
Always write 1 after reset.
2-0 0 W 0h Must write 0.

9.6.1.4 Register 308h (address = 308h)

Figure 170. Register 308h
7 6 5 4 3 2 1 0
HIGH IF MODE<5:4> 0 0 0 0 0 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 33. Register 308h Field Descriptions

Bit Field Type Reset Description
7-6 HIGH IF MODE<5:4> R/W 0h Set the HIGH IF MODE[7:0] bits together to FFh.
Improves HD3 by a couple of dB for IF > 100 MHz.
5-0 0 W 0h Must write 0.

9.6.1.5 Register 41Dh (address = 41Dh)

Figure 171. Register 41Dh
7 6 5 4 3 2 1 0
0 0 0 0 0 0 HIGH IF MODE2 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 34. Register 41Dh Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 HIGH IF MODE2 R/W 0h Set the HIGH IF MODE[7:0] bits together to FFh.
Improves HD3 by a couple of dB for IF > 100 MHz.
0 0 W 0h Must write 0.

Register 422h (address = 422h)

Figure 172. Register 422h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 DIS CHOP CHB 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 35. Register 422h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 DIS CHOP CHB R/W 0h This bit disables the chopper.
Set this bit to shift the 1/f noise floor at dc.
0 = 1/f noise floor is centered at fS / 2 (default)
1 = Chopper mechanism is disabled; 1/f noise floor is centered at dc
0 0 W 0h Must write 0.

Register 434h (address = 434h)

Figure 173. Register 434h
7 6 5 4 3 2 1 0
0 0 DIS DITH CHB 0 DIS DITH CHB 0 0 0
W-0h W-0h R/W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 36. Register 434h Field Descriptions

Bit Field Type Reset Description
7-6 0 W 0h Must write 0.
5 DIS DITH CHB R/W 0h Set this bit with bits 5 and 4 of register 01h.
00 = Default
11 = Dither is disabled for channel B. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
4 0 W 0h Must write 0.
3 DIS DITH CHB R/W 0h Set this bit with bits 5 and 4 of register 01h.
00 = Default
11 = Dither is disabled for channel B. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
2-0 0 W 0h Must write 0.

Register 439h (address = 439h)

Figure 174. Register 439h
7 6 5 4 3 2 1 0
0 0 0 0 SP1 CHB 0 0 0
W-0h W-0h W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 37. Register 439h Field Descriptions

Bit Field Type Reset Description
7-4 0 W 0h Must write 0.
3 SP1 CHB R/W 0h This bit sets the special mode for best performance on channel B.
Always write 1 after reset.
2-0 0 W 0h Must write 0.

9.6.1.6 Register 51Dh (address = 51Dh)

Figure 175. Register 51Dh
7 6 5 4 3 2 1 0
0 0 0 0 0 0 HIGH IF MODE3 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 38. Register 51Dh Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 HIGH IF MODE3 R/W 0h Set the HIGH IF MODE[7:0] bits together to FFh.
Improves HD3 by a couple of dB for IF > 100 MHz.
0 0 W 0h Must write 0.

Register 522h (address = 522h)

Figure 176. Register 522h
7 6 5 4 3 2 1 0
0 0 0 0 0 0 DIS CHOP CHC 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 39. Register 522h Field Descriptions

Bit Field Type Reset Description
7-2 0 W 0h Must write 0.
1 DIS CHOP CHC R/W 0h This bit disables the chopper.
Set this bit to shift the 1/f noise floor at dc.
0 = 1/f noise floor is centered at fS / 2 (default)
1 = Chopper mechanism is disabled; 1/f noise floor is centered at dc
0 0 W 0h Must write 0.

Register 534h (address = 534h)

Figure 177. Register 534h
7 6 5 4 3 2 1 0
0 0 DIS DITH CHC 0 DIS DITH CHC 0 0 0
W-0h W-0h R/W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 40. Register 534h Field Descriptions

Bit Field Type Reset Description
7-6 0 W 0h Must write 0.
5 DIS DITH CHC R/W 0h Set this bit with bits 3 and 2 of register 01h.
00 = Default
11 = Dither is disabled for channel C. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
4 0 W 0h Must write 0.
3 DIS DITH CHC R/W 0h Set this bit with bits 3 and 2 of register 01h.
00 = Default
11 = Dither is disabled for channel C. In this mode, SNR typically improves by 0.2 dB at 70 MHz.
2-0 0 W 0h Must write 0.

Register 539h (address = 539h)

Figure 178. Register 539h
7 6 5 4 3 2 1 0
0 0 0 0 SP1 CHC 0 0 0
W-0h W-0h W-0h W-0h R/W-0h W-0h W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 41. Register 539h Field Descriptions

Bit Field Type Reset Description
7-4 0 W 0h Must write 0.
3 SP1 CHC R/W 0h This bit sets the special mode for best performance on channel C.
Always write 1 after reset.
2-0 0 W 0h Must write 0.

9.6.1.7 Register 608h (address = 608h)

Figure 179. Register 608h
7 6 5 4 3 2 1 0
HIGH IF MODE<7:6> 0 0 0 0 0 0
W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 42. Register 608h Field Descriptions

Bit Field Type Reset Description
7-6 HIGH IF MODE<7:6> R/W 0h Set the HIGH IF MODE[7:0] bits together to FFh.
Improves HD3 by a couple of dB for IF > 100 MHz.
5-0 0 W 0h Must write 0.

9.6.1.8 Register 70Ah (address = 70Ah)

Figure 180. Register 70Ah
7 6 5 4 3 2 1 0
0 0 0 0 0 0 0 PDN SYSREF
W-0h W-0h W-0h W-0h W-0h W-0h W-0h R/W-0h
LEGEND: R/W = Read/Write; W = Write only; -n = value after reset

Table 43. Register 70Ah Field Descriptions

Bit Field Type Reset Description
7-1 0 W 0h Must write 0.
0 PDN SYSREF R/W 0h If the SYSREF pins are not used in the system, the SYSREF buffer must be powered down by setting this bit.
0 = Normal operation
1 = Powers down the SYSREF buffer