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Digital potetiometer AD5227 reset output value

Question asked by meir.mardechayev@phnx.co.il on Aug 3, 2014
Latest reply on Aug 17, 2014 by msamera

Hello,

 

My name is Meir and I am DFAE at Phoenix technologies in Israel.

 

Sensible Medical, one of my customers, is interested in digital potetiometer AD5227 for LDO output voltage control.

They don't want the system to remember the last state of the AD5227. Therefore, they would like to have a reset to its state before
programming its state by the up/down clock.

1. How can we reset the AD5277? - in the datasheet, it is specified that "The AD5227 presets to midscale at power-up". Does
"power-up" is defined by CS pin, or by the Vdd biasing?

2. As we understand, Vdd must be biased before any current goes through the potentiometer. If "reset" is done only by Vdd does
from low to high, is there any chance of damage to the AD5227 by the low currents of the feedback loop of the ADP323?

3. What is the expected value of the resistance seen between pads A, W and B of the AD5227 when Vdd is off?

 

Thanks,

Meir

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