ADC34J42 Datasheet, PDF (57/90 Pages) Texas Instruments – ADC34J4x Quad-Channel, 14-Bit, 50-MSPS to 160-MSPS, Analog-to-Digital Converter with a JESD204B Interface

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ADC34J42, ADC34J43, ADC34J44, ADC34J45
SBAS664B – MAY 2014 – REVISED NOVEMBER 2014
9.5 Programming
The ADC34J4x 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); see Figure 161. 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.
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