UCC5870-Q1: question about wave of DESAT function

Hello Jay,

Thanks for your questions!

Jay wang said:

Q1:what is different between wave of OUTH and wave of VGE?(from the first picture, i think two waves may be same)

In figure 7-17 the OUTH and OUTL waveforms show the state of the OUT pins, in other words, what they would be with nothing connected to them. This is close to what would be measured at the pins of the device, before the gate resistors.

The VGE waveform shows a realistic waveform of VGE as the outputs drive a capacitive load, as measured on the power switch side of the gate resistors.

Jay wang said:

Q2：whether must i connect power switch(IGBT), when i want to verify the function of DESAT ?

To accurately verify the DESAT function the actual power switch should be used. If the device is switched with the DESAT circuit disconnected from the power switch the DESAT fault will always be reported (Unless it is disabled) because there is no path for the desat current other than charging the blanking capacitor. 

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Regards,

Daniel