PMP20199: PMP20199: Output Voltage going above desired value at Start up

Part Number: PMP20199

Hi Expert,

I had posted this same issue previously. I am still not able to get down the overshoot at start up. I have tried placing preload resistors at the output. Placing the preload at the Secondary 1 output did help in reducing the droop time at secondary 2 but did not resolve the overshoot problem at both outputs.

The test conditions are:

1. Input Voltage: 230V 50Hz Ac

2. Output 1: 54Vdc at 0.56A

    Output 2: 5V dc

Below I am attaching the waveforms with and without load:

1. No Load at Secondary 1 output:

Note: VDD in the above waveform is VLED(Secondary 2 output) passed through a 3V3 LDO.

2. Preload Resistor of 733 ohms placed at Secondary 1 output:

Please help me resolve this problem.

Thank you for your assistance.

Regards,

Mikha