TPSM863257: Power Good

Part Number: TPSM863257

Tool/software:

Hello, please add some PG (PGOOD) information to the datasheet.

Will PG stay High-Z ("good") while VIN < UVLO?

Please clarify PG start-up delay. "TPGDLY 28 us PG from high-to-low" is from timestamp VIN reaches UVLO and "TPGDLY 1 ms PG from low-to-high" is from timestamp VFB reaches "VPGTH VFB rising (good)"???

Thanks

2 months ago

0 Shipeng Cheng 2 months ago

TI__Genius 10510 points

Hi AP,

When VIN < UVLO, PG state is uncertain because internal logic is disable.

All PG delay time is based on threshold of FB voltage.

Thanks.

0 AP 2 months ago in reply to Shipeng Cheng

Intellectual 380 points

... I still dont's understand the two stated delay times in the startup conext. Please give an example that covers both TPGDLY times. And what happens when VIN exceeds UVLO (during ramp up) but VFB has not reached any threshold yet? I really(!) would prefer a detailed PG state table as in many other TPS datasheets.

Regards.

0 Lucia Gao 2 months ago in reply to AP

TI__Mastermind 21230 points

Dear Sir,

I would check the waveform and state table for your during these days. Thank you!

BRs

Lucia

0 Lucia Gao 2 months ago in reply to Lucia Gao

TI__Mastermind 21230 points

Dear Sir,

You can refer to below waveform to better understand PG delay time.

We force fb from 0.42V to 0.64V square waveform. Trigger PG.

You can read from below waveform that delay time is around 1ms. (PG delay from low to high)

And we force fb from 0.64V to 0.42V square waveform. Trigger PG.

You can read from below waveform that delay time is around 29us. (PG delay from high to low)

Now if you look at the delay time specified in datasheet about PG delay time again, I hope it can help you to better understand it.

Thanks!

BRs

Lucia

0 Lucia Gao 2 months ago in reply to AP

TI__Mastermind 21230 points

Dear Sir,

When VIN exceed UVLO, but vfb has not reached any threshold, PG will be low. Thanks! Below waveform is an example for your reference (PG pulled up to external Vcc.

Thanks!

BRs

Lucia

0 Lucia Gao 2 months ago in reply to Lucia Gao

TI__Mastermind 21230 points

Pls refer to this logic table.

Thanks!

BRs

Lucia

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TPSM863257: Power Good