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MM912J637 - using VOC and VSGC to help compensate external circuit

Question asked by Ian Wilson on Oct 6, 2015
Latest reply on Oct 12, 2015 by Tomas Vaverka

Hello all,

 

We have a small resistance (a fuse) in the lead feeding VSENSE and also powering the circuitry.  Current consumption changes therefore have a small effect on the measured voltage.  We have a state where a reasonably well known increased load on our circuit is switched in.  So we know when there is an extra current draw through the fuse.

We can work out suitable offset (and maybe gain) corrections (in the order of 5mV or less).

 

It seems to me we can tweak the VOC offset compensation register to also include our external circuit offset as well as the device offset. But only if there is sufficient range in the 637's compensation registers.

 

This will depend on the range of offsets we expect to see from the device itself.  From the datasheet the 637's compensation range is ~ +/- 9 mV with resolution of about 0.07 mV.  However, we don't know range is normally used by the devices. I.e. what is the production spread.

 

Is there any information on the spread of offset and gain compensations across production?

 

Many thanks,

Ian Wilson

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