CORRECT POWER UP SEQUENCE:
It is essential that all inputs to the AD7895 must remain below the VDD supply,
otherwise internal esd diodes will switch on and unless the current is limited
permanent damage may be caused to the AD789. During power-up, you should ensure
that the digital inputs are not floating and the analog input is within VDD.
Using a pull down resistor(or a pull-up resistor to VDD)during the power up
phase will ensure this is the case.
The correct power up sequence is as follows: Vdd – Analog inputs – Digital
inputs - Digital outputs.
CORRECT TIMING OF /COMVST, SCLK
This has been the cause of some customers having what appears to be a ‘latch-
up’. Either the /CONVST is incorrect or the timing in general is an issue.