We’ve made a 150W (5V / 30A) design using the UCC2891 active clamp converter
An undervoltage test is to be performed by overloading the UCC2891 to over current limit and let the output voltage droop to 4.8V. Below 4.8V the op-amp – opto-coupler circuit pulls the SD pin of UCC2891 to ground shutting down the device
This protection mechanism works fine till -15 deg C and below this the UCC2891 fails to restart after removing the fault. It seems to be in hic-up mode
I need your advice on whether this type of testing is normal in telecom systems i.e. overloading the output to hit current limit and then droop the output voltage to trigger the protection circuit
The design works fine, if I do the undervoltage testing by just modifying the TL431 reference voltage to set output voltage below 4.8V at -35 deg C
