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AD7708 absolute ratings

Question asked by tneagoe on Mar 10, 2015
Latest reply on Mar 18, 2015 by RobK

Hello there,

 

I have a question about the absolute ratings of the AD7708.

According to the datasheet:

 

AVDD to DVDD . . . . . . . . . . . . . . . . . . . . . . . . –5 V to +5 V

 

Typically, in my design: the AVDD is a 5.7V and DVDD at 3.3V; within the above limits.

The   thing is that at power up, AVDD is provided before DVDD and theoritically, it
could have 5.7V between them. 

When I look at the voltages during startup,  the difference is limited to around 1.8V.

I don’t know what is limiting it; is it something internally? 

I am also planning to delibarately shut-down the DVDD for  power savings

and I would like to verify what are the constraints.

Please advise,

Teodor

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