UCC256302: About operation when load is added to output

Masazumi Ishii

Part Number: UCC256302

hello.

I made a prototype board using UCC 256302.
I turned on the power supply.
We output voltage as specified.

Setting the load at about 0.8 A will lower the output voltage.

I thought that the overcurrent protection circuit operation is taking place, I lowered the resistance of the ISNS pin, I tried lowering the capacitance of the shunt capacitor
But the situation did not change.

Please let me know what you think is the cause.

Thank you.

over 7 years ago

0 Benjamin Lough over 7 years ago

TI__Mastermind 27135 points

Hi Masazumi-san,

Thanks for your interest in UCC256302. I would first check if there is a fault occurring at heavy load. If there is a fault, you would see RVCC disable and re-enable periodically instead of being a steady 12V. I would then check the FB pin voltage to make sure the FB signal is adjusting with load. Are you able to share a schematic? Do you have any waveforms you are able to share?

Best Regards,
Ben Lough

0 Benjamin Lough over 7 years ago in reply to Benjamin Lough

TI__Mastermind 27135 points

Hi Masazumi-san,

Do you have any waveforms you are able to share? Are you able to share schematic?

Best Regards,
Ben Lough

0 Benjamin Lough over 7 years ago in reply to Benjamin Lough

TI__Mastermind 27135 points

Hi Masazumi-san,

Since it has been 2 weeks since your last response, I will go ahead and close this thread. Please feel free to make a new post if you need further assistance with this.

Best Regards,
Ben Lough

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UCC256302: About operation when load is added to output