Low-side current sensing with G4 series.

[helbo]

I`m struggling with low side current sensing. In AN5306 ST proposed a lowside current sensing with the STM32G4 series. Here is a screenshot.

 

Furthermore the range of the opamp input voltage ist from 0V to VDDA, as can be seen here

Source

How can this be done without damaging the the chip? As far as i understand the switching process of the three halfbridges, there is a freewheling current inbetween every positive pulse of the top side pwm cycle. This current flows “backward�? through the shunt and through the freewheling diode of the lowside mosfets. So this current causes a negative voltage drop at the shunt resistor.

I am missing something? Why is ST recommanding this allthough it can harm my chip?

Best regards

[Laurent Ca...]

Dear @Community member​ 

Sorry for the late answer.

Do you have still this problem to solve?

And just in case, if not, do not hesitate to share the final solution you found. Thanks by advance.

Best regards

Laurent Ca...

[helbo]

Unfortunately, yes i do.

I have not found an answer to my question, yet.

Best regards