TPS549D22: Power sequence, PMbus

Oba

Genius 17295 points

Part Number: TPS549D22

Hello,

I have two questions for power sequence, specially about PMbus lines, of TPS549D22.

Due to the system requirement, power rail of PMbus pull-up is powered up before PVIN and VDD powering up.

Also it is powered down after PVIN and VDD powering down.

Is there any problem due to this power sequence? Could this power sequence damage the device?

Can PMbus pull-up voltage be over PVIN and VDD voltage if pull-up voltage is under 5.5V?

Regards,

Oba

over 7 years ago

0 JohnTucker over 7 years ago

TI__Guru**** 191445 points

Let me check on this. Ill get back to you soon.

0 Oba over 7 years ago in reply to JohnTucker

TI__Genius 17295 points

Hello,

Any update?

Regards,
Oba

0 JohnTucker over 7 years ago in reply to Oba

TI__Guru**** 191445 points

Not yet. I'll ping them again.

0 Oba over 7 years ago in reply to JohnTucker

TI__Genius 17295 points

Hello,

Any update?

Regards,
Oba

0 JohnTucker over 7 years ago in reply to Oba

TI__Guru**** 191445 points

I will ask again tomorrow.

0 JohnTucker over 7 years ago in reply to JohnTucker

TI__Guru**** 191445 points

Oba,

We have finally verified the answer. Yes, it should be fine to power up SF’s PMBus CLK, DATA and ALERTZ pins before VDD and VIN. We used fail-safe I/O buffers and ESD cells for those pins, so it’s fine to apply voltages on CLK, DATA and ALERTZ pins before VDD and VIN, as long as the voltages are below recommended max values on the datasheet.

Let me know if you need additional assistance.

Power management

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TPS549D22: Power sequence, PMbus