LM5034: Will LM5034 work in fold-back mode when OCP if connecting RES pin to GND?

Johnny Guo

Part Number: LM5034

Hi, team,

My customer would like to check one question about LM5034.

Will LM5034 work in fold-back mode when OCP if connecting RES pin directly to GND? In datasheet, it only describes the hiccup mode when RES pin connected with a cap to GND.

Thanks.

Johnny

over 6 years ago

0 Joe Leisten over 6 years ago

TI__Expert 3095 points

Hi Johnny Guo,
Pulling the RES pin directly to GND will disable hiccup mode. In this case peak current mode control should be active but the power stage will keep running.
This is not fold-back mode because the power stage will continue to deliver full current.
I hope this answers your question.
Joe Leisten

0 Johnny Guo over 6 years ago in reply to Joe Leisten

TI__Expert 4910 points

Hi, Joe,

So if we pull the RES pin to GND, and we increase the output current by electronic load, the power stage keep running but how will the output voltage behave?

Thanks.

Johnny

0 Joe Leisten over 6 years ago in reply to Johnny Guo

TI__Expert 3095 points

Hi Johnny,
The answer depends upon the type of load that you use (CC, CR, CV). The output current will be limited and the voltage will drop as necessary to achieve this. The part will keep running.
I hope this answers your question.
Joe Leisten

0 Johnny Guo over 6 years ago in reply to Joe Leisten

TI__Expert 4910 points

Hi Joe,

When I pull RES pin to GND, the overcurrent mode changed from Hiccup to power limit. But I think the power limit mode is not fold-back, right? Correct me if I’m wrong.

Thanks

Johnny

0 Joe Leisten over 6 years ago in reply to Johnny Guo

TI__Expert 3095 points

Hi Johnny,
That is correct. Current limit means that the output current is held constant as the voltage is pulled down by the load.
Foldback suggests that as the output voltage is pulled down by the load the current limit reduces also.
I hope this is clear.
Thanks
Joe Leisten

0 Johnny Guo over 6 years ago in reply to Joe Leisten

TI__Expert 4910 points

Thanks Joe for feedback.

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LM5034: Will LM5034 work in fold-back mode when OCP if connecting RES pin to GND?