Other Parts Discussed in Thread: LMP8640, LMP8601, INA240
Hi everyone,
while running a current controlled valve, we noticed some unexpected signals at the output of the LMP8640HVMK-T. There are significant spikes every time the PWM switches the high-side-switched valve on and off.
The circuit we use applies a 24V PWM to control current, which is measured by a 25mOhm Shunt, which in turn is used with the LMP8640HV-T to supply the current signal to an µC ADC.
A zoom on the negative and positive going edge provides details;
This seems to be some effect that has to do with CMRR, but it does not correlate to datasheet value of 103 dB.
Additional info:
- A competitor IC with similar function performs as expected
- When using the LMP8640 in a low side switching scenario, these voltage dips do not occur.
Can someone explain this behaviour and how it could have been seen from the datasheet that the LMP8640 might act this way in this particular application.
Thanks in advance and a nice weekend!
Simon Bauer