This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UC2845A: VCC drop when load current change instantly

Part Number: UC2845A


We faced a a problem when we just start up UC2845A as flyback circuit for fan.

When the system start up, the fan will make load current from 0 to 3A within 200ms.

The secondary side voltage will be from 24V up to 25V and this will cause UC2845A stop switching so the auxiliary side voltage (VCC) will drop dramatically from 16V.

The schematic is shown as below.

Is there any suggestion of modifying the circuit to solve this case?

Thank you.

Best Regards,