DPA424 input power rise

Hello SV,

Thank you for using Power Integrations product.

It seems that something is wrong with more consumption in the circuit.

Can you monitor the output voltage and the feedback circuitry to see if anything is changing with the input power. we can start the debug from there.

best Regards

Hi,

In the attached file, some scope pictures can be found.
Regarding the output power and feedback signal, these are constant over time.

Another thing to note is that the rise in input power is exponential.
I also noticed that when i powered the device for some time and let the input power rise, next i put it off for some time and thereafter i put it back on, the input power rises more quickly then when i leave it off longer. (So maybe something temperature related?)

Hello SV,

All the waveform looks normal. Is this waveform capture during the normal operation or after the power rise?

If this waveform is captured during the normal operation, please also try to capture the same waveform during power rise.

If this waveform is captured during or after power rise, this means the 3.3V channel and the feedback loop is normal. there is something wrong with other outputs, you might want to compare the similar waveform for other output windings to see which has significant change during the power rise.

Best Regards

Hi,

I measured all outputs during the power rise, but didn't notice any significant changes.
The device can now deliver up to 4.5W without any problems, but higher powers give problems.

Could this be the behaviour when the transformer goes into satturation? Is there a way to test this?
In attachement you can find the datasheet of the transformer.
We asked for a transformer with a satturation current of 400mA.