AD9640SLASHPCB datasheet(30/41 Pages) AD

30 / 41 page

AD9640

Preliminary Technical Data

Rev. PrD | Page 30 of 41

BUILT-IN SELF-TEST (BIST) AND OUTPUT TEST

The AD9640 includes built-in test features to enable verification

of the integrity of each channel as well as to facilitate board level

debugging. A BIST (built-in self-test) feature is included which

verifies the integrity of the digital data path of the AD9640.

Various output test options are also provided to place

predictable values on the outputs of the AD9640.

BUILT IN SELF TEST (BIST)

The BIST is a thorough test of the digital portion of the selected

AD9640 signal path. When enabled, the test runs from a user

selectable internal source (PN or sine) through the digital data

path starting at the ADC block output. The BIST sequence will

run for 256 cycles and stop. The BIST signature value for

channel A or B will be placed in registers 0x024 and 0x025. If

one channel is chosen, its BIST signature is written to the two

registers. If both channels are chosen, the two channels’ results

are XOR’ed and placed in the BIST signature register. The

outputs are not disconnected during this test, so the PN

sequence can be observed as it runs. The PN sequence can be

continued from its last value or start from the beginning based

on the value programmed in register 0x00E bit 2. The BIST

signature result will vary based on the channel configuration.

OUTPUT TEST MODES

The output test options are shown in table x.x. When an output

test mode is enabled, the analog section of the ADC is

disconnected from the digital backend blocks and the test

pattern is run through the output formatting block. As

indicated in table x.x some of the test patterns are subject to

output formatting and some are not. The seed value for the PN

sequence tests can be forced if the PN reset bits are used to hold

the generator in reset mode by setting bits 4 or 5 of register

0x0D. These tests can be performed with or without an analog

signal, but do require an encode clock.

AD9640/PCB Datenblatt(PDF) 30 Page - Analog Devices