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Explorer II
June 8, 2024
Question

STPM34 shunt measuring

  • June 8, 2024
  • 2 replies
  • 1128 views

Hi everybody,

I made a circuit for the STPM34, but I keep destroying my components :)

The first image is what my circuit looks like, I followed the datsheet closely, yet there seems to be a mistake somewhere.


I've noticed it goes wrong at my current measuring circuit, namely the 1k resistors burn and the STPM34 explodes.
Between the shunt and the pins IIP1 and IIN1 I measure 1kOhm, as it should be.

 

I made a quick test setup with a 1V DC supply, and noticed the voltage drop over the 1kOhm resistor is way too high (200mV). The setup of this test circuit is shown in the notes.

The orientation of the IC is correct, so I'm connected to the right pins.

Any ideas what may be the cause for this high voltage drop?

2 replies

Senior III
June 9, 2024

The current needs to controlled, as per your 2nd circuit, the current is just 1ma(ohm's law). So it can't create 200mv. Please check the resistors. The current is always determined by the load. 

AScha.3
Super User
June 9, 2024

Hi,

just i cannot find my big blue crystal ball...

so tell me: hi-side voltage? , max. supply voltage?, same gnd level ? , voltage at current-test resistor ?.

+ full circuit.

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