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Possible issue with Adum3482

Question asked by Gavin.Melville on Oct 29, 2013
Latest reply on Nov 7, 2013 by Gavin.Melville

Hi,

 

We designed several Adum3482 into a product and found to our surprise that the VDDL1 pin can power our entire board -- with current flowing out of pin 1.

 

Schematic fragment here.

 

adum3482.jpg

 

All IO is 3.3V, and I assumed that the best way of using this was to run VDD from 5V, and the logic level translators from 3.3V.  The problem is that I have approx 180mA flowing back out of pin 1, happening on multiple devices.   Raising pin 1  to 5V corrects this -- obviously.  

 

I did wonder if CTRL1 was part of the logic translator "domain" so I removed the 5V from there and drove it with 3.3V, no change.

 

There is a drop of approx 1.1V when supplying 180mA, so I suspect there is a diode involved.  The device does get hot when supplying current.

 

Has anyone ever tried these devices with VDDL lower than VDD ?

 

This is an urgent request, volumes in 6 digits involved.

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