EVSPIN32G4: Current sense feedback resistor values

[JulesC]

I all,
I have a question regarding the EVSPIN32G4 board, specifically concerning the feedback resistors used in the current sensing network (default value: 11 kΩ).

I am considering replacing them with 150 kΩ resistors. My main concern is whether this significant change will trigger the Overcurrent Protection (OCP) prematurely or cause stability issues with the internal op-amps.

Has anyone experimented with such values, or are there specific hardware limitations I should be aware of?

Best regards, Jules

[AScha.3]

Hi,

just : WHY you want replacing them with 150 kΩ ? ( = this spoils the opamp bridge. )

+

Now -with 11k - the current measuring range of the opamp -> ADC is about 0...50A ;

this matches the capability of the board (and the 100A mosfets) quite good;

your change would spoil the opamp bridge and give a range of about 0...3 A , what seems quite useless to me.

[JulesC]

Hi @AScha.3,

Thanks for the response.

I thought I could get better precision because I don't need such a wide range, as I am operating with small motors. But, based on what you’re saying, it seems I would be sacrificing stability or hitting the op-amp's limits ? Even if I change the resistors R41 & R47 to 300kOhm ?

[AScha.3 · Accepted solution]

Seems you could try this, with 150k + 2x 300k , to get a 2A max. range (about) . But you get high impedance then, very sensitive to stray in.

But why not reducing the input of the diff-amp , R44 + 50 ?  try 1k5 -> 150 r , so you get 10x gain and 1/10 current range; you really need only so low range ?