TPS54910: PG voltage up when EN shutdown

Johnny Guo

Part Number: TPS54910

Hi, team,

My customer met one issue about TPS54910 PG signal.

In customer's design, PG is pulled up to BIAS with 4.7k resistor. They found when TPS54910 is shutdown, PG voltage will be like below.

We tested some waveform to root the cause, and VIN, BIAS, EN, SW is normal without any issue.

Could you help verify it on EVM and give me the test result?

Thanks.

Johnny

over 6 years ago

0 Vental Mao over 6 years ago

TI__Expert 5745 points

Hi:
Does the PG pin connect to any other device? If yes, can you show me the schematic?

0 Johnny Guo over 6 years ago in reply to Vental Mao

TI__Expert 4910 points

Vental,

PG is connected to CPLD, but we have verified PG signal is still the same if removing CPLD. No schematic can be supplied, I just checked it at customer side, all design is good.
I think John Tucker may have one TPS54910 EVM on hand, please get it and do some bench test.

Thanks.
Johnny

0 JohnTucker over 6 years ago in reply to Johnny Guo

TI__Guru**** 191445 points

I tested a TPS54910 EVM. It more or less reproduces your results. I'll provide waveforms if you contact me directly. Basically. when VIN is between about 0.6 V and 1.2 V. the PWRGD function is not well defined. An external pull up can pull it up even if teh output voltage is out of regulation. This is not unique to TPS54910, but is applicable to pretty much all ICs.

0 Johnny Guo over 6 years ago in reply to JohnTucker

TI__Expert 4910 points

Thanks John, I will email to you for test result.

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TPS54910: PG voltage up when EN shutdown