TPS54610: SS/ENA voltage jump up when power off

Johnny Guo

Part Number: TPS54610

Hi, Team,

I have one issue from customer about TPS54610.

Below is customer's schematic, one 10nF cap is palced at SS/ENA pin.

When TPS54610 is powered off (VIN drops below UVLO), SS/ENA pin voltage will jump to 0.9V as shown below. We checked VIN and SW waveform as below.

Could you please check whether the SS/ENA voltage jump is normal or not after TPS54610 stops switching?

Thanks.

Johnny

Thanks.

Johnny

over 5 years ago

0 JohnTucker over 5 years ago

TI__Guru**** 191445 points

Johnny,

We will look into it. It may take a few days if we need to order an EVM to check.

0 Johnny Guo over 5 years ago in reply to JohnTucker

TI__Expert 4910 points

John,

Please help verify it on EVM. Looking forward to your feedback.

Thanks.
Johnny

0 JohnTucker over 5 years ago in reply to Johnny Guo

TI__Guru**** 191445 points

Johnny,

I think this is normal operation:

Vin voltage source is turned off.

EN tracks Vin until Vin reaches the UVLO voltage at about 2.8 V.

UVLO stop causes SS/ENA to discharge through the internal discharge circuit.

Vin continues to drop.

At around 1.2 V the internal logic does not have enough voltage to operate,but there is enough voltage for internal junctions to be forward biased, so SS/ENA is pulled back up to Vin.

Both Vin and SS/ENA discharge to ground.

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TPS54610: SS/ENA voltage jump up when power off