UCC2804: repeatedly start up

Howard Zou

Part Number: UCC2804

Hi, my customer is using UC2804 as aux power. The schematic is as below.

BUS+ and BUS- are from PV panel. The PV panel's voltage will start rising with light on the panel.

Now when UC2804 start working when PV panel's voltage rises to a level. They will observe it repeatedly start up. But they measured VCC with multimeter, it's always 9.3V. I guess the repeatedly start up is causing by the turn on:12.5V and off:8.3V threshold. So I will ask them to measure VCC through scope.

But the start up repeat frequency is so high that I'm not sure if it's caused by the on and off threshold.

Any other pin's waveform is suggested to measure to determine the root cause?

over 5 years ago

0 Peter Meaney over 5 years ago

TI__Mastermind 31580 points

Hi Howard,

The customer really needs to use an oscilloscope to debug the start-up issue, please ask them to post the waveform on the Vcc pin during start-up.

Is the Vcc-Aux rail supplied from another source like a winding on the transformer?

Thanks

Peter

0 Peter Meaney over 5 years ago in reply to Peter Meaney

TI__Mastermind 31580 points

Hi Howard,

Since there has been no activity on this post for 10 days I am closing this post. I hope the customer has made some progress on the issue in the meantime. If there are more questions please open a new post.

Regards

Peter

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UCC2804: repeatedly start up