I'm considering #1, although I don't think the INA196 is the correct=20
solution for this as there are warnings in the datasheet mainly because=20
it's designed for a low-impedance connection to the shunt...  I am=20
considering rolling my own with some precision matched resistor pairs..

On #2... Yep, close to being there myself.   I was hoping not to end up=20
there, although it's looking more and more likely.

-forrest

On 4/22/2012 10:04 AM, Dwayne Reid wrote:
> At 02:49 AM 4/22/2012, Forrest Christian wrote:
>> I'm currently using an INA196 high side shunt amplifier in a couple of
>> applications.   As I asked/discussed a couple of weeks ago, one of them
>> involves current monitoring the currents through some P-channel FETS,
>> and am looking at moving the sensing from a sense resistor to sensing
>> across the FETS.
>>
>> I of course need to deal with the situation where the FET is off,
>> producing a high differential voltage across the amplifier.
> I've handled this in a couple of different fashions.
>
> 1) Just rely upon well-matched high-value series resistors to the
> op-amp and add clamp diodes across the op-amp inputs.
>
> 2) Use another (small) FET who's gate is tied to the gate of the main
> FET - use that small FET to disconnect the sense lead from the main
> FET while it is turned off.
>
> I've used both techniques successfully in the past.
>
> dwayne
>

--=20
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