Voltage drop out on output pins of PIC18F46K22

[FvM]

Still wrong, COM is shorting the ULN output via free wheeling diodes. But I understand you don't use ULN2004 at all, so the schematic detail is irrelevant?



Time to review the IR21362 reference design. It has a low ohmic shunt between bridge low side source terminals and DC-. The source side is connected to COM, the DC- side to VSS. Itrip has a fixed threshold of 0.5 V, by adjusting the voltage divider you set the overcurrent limit.



Now compare with your schematic. You don't have a current measurement shunt, thus Itrip feature can't be used. Simply tie COM, VSS and Itrip to ground.

 

[jean12]

Thank you,I am going to try I let you know the outcome.

After making the connections as you advised no change held,the LED on Fault pin starts lighting once the DC bus become greater than the control board power supply voltage

Pic+IR21362 has a power supply of +15V when the DC but becomes higher than that the LED on FAULT pin starts lighting as the voltage increases,the illumination increases also.

See the DSO snapshot of the waveform I get when the probe is connected on the two Source pins of the 2 top IGBTs.

Thanks

 

[KlausST]

Hi,

Pic+IR21362 has a power supply of +15V

Sure..the PIC has 15V supply? What PIC is it?

Klaus

 

[FvM]

Fault LED indicates either overcurrent detection or Vcc undervoltage. So I presume the circuit faults mentioned before (e.g. IR21362 Vss connection) haven't been fixed yet.

See the DSO snapshot of the waveform I get when the probe is connected on the two Source pins of the 2 top IGBTs.

"the probe" means what? Differential probe? I won't expect to get correct measurements with the ground clip of a standard oscilloscope prober connected to a hot circuit node.