TPS65251: TPS65251 ENx pin behavior such as square wave

Mitsuharu Iwasaki7

Intellectual 540 points

Part Number: TPS65251

Hello all,

When VIN is supplied from 4.4V to 4.8V, EN1 and EN2 pin have square wave such as attachied photo.

I couldn't find functional descrpition in the TPS65251 specification. Could you tell me why it is occured?

What trriger/specification does it happen? When PMIC detects it, What do ENx do?

Best Regards.,

Mitsuharu Iwasaki

over 7 years ago

0 Zhao Ma over 7 years ago

TI__Genius 15135 points

Hi, Sir

1. How do you connect EN1/2 pin? floating or external input signal?
2. If you not change Vin voltage, what will happen?

0 Mitsuharu Iwasaki7 over 7 years ago in reply to Zhao Ma

Intellectual 540 points

Hello Zhao,

En1 and EN2 are floating and Vin is changed. I think VIN is cross UVLO, this behavior is occured.
But it isn't expalined in the data sheet.

Best Regards.,
M.Iwasaki

0 Zhao Ma over 7 years ago in reply to Mitsuharu Iwasaki7

TI__Genius 15135 points

Hi, Sir

I have checked on EVM, VIN UVLO will not pull down ENx pin.
Please double check the EN1/2 connection, I suspect they are pull low by external circuit.

If you increase VIN voltage to 6V, what will happen?

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TPS65251: TPS65251 ENx pin behavior such as square wave