I found VFO output of IPM IKCM20L60 is high. And it's send to microcontroller TMS320F28034 via a diod and a10 K resistor. Before 10K resistor it's high 3.3V. But at MCU pin it's low. Mcu working fine other work. And MCU try to on IPM for 2 second and goes mcu output off. Can anyone help to digones this.

 

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Please post a schematic.

 

You have an air conditioner with a controller board outside? Make and model please.

 

Check the type of diode being used. If it's a standard silicon diode (forward voltage around 0.7V), it could be pulling the voltage down enough that the MCU sees a low level.