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AD7280A cell bypass output drive strength

Question asked by Julian on Oct 26, 2011
Latest reply on Dec 16, 2011 by AndyR

The AD7280A has cell bypass outputs that claim to be able to drive 5V above each cell's negative terminal to turn on a FET. There is no mention of the drive strength of these outputs, but, from the datasheet, I can deduce they are provided by some sort of simple charge pump internal to the chip. This is perhaps why the listed time to turn on an 80pF load is 30us. Using CV=IT I get a drive strength of only 30uA.

 

In my application I need more drive strength than that, as we need to be certain that the bypass cannot come on by accident. At the very least I need strong (~1 to 5k) pull-downs on the lines, so that even if the CBx output is floating, noisy, or is not connected (e.g. a production soldering fault) the bypass transistor cannot come on. My cell balance hardware is also not on the same PCB as the AD7280A, necessitating additional protection circuitry.

 

Does anyone have specs for this drive strength or experience with these outputs?

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