TPS65981: Period from power-up to starting accessing SPI flash

Oba

Part Number: TPS65981

Hello

I would like to know the period from VIN_3V3 reaching a certain voltage during power-up to starting accessing SPI flash memory to confirm whether SPI flash ready time from power up is enough or not.

Do you have this kind of information? If it is not available, could you tell me just internal POR delay time?

Regards,

Oba

over 6 years ago

0 Rahul Sharma16 over 6 years ago

TI__Expert 6430 points

Hi Oba,

It's couple of milliseconds, however, you don't have to worry about this as we recommend to power up the SPI flash from LDO_3V3 rail which takes care of any such delay.

Please click "This resolves my issue" if I was able to answer your query.

Thanks,
Rahul

0 Oba over 6 years ago in reply to Rahul Sharma16

TI__Genius 17305 points

Hello Rahul,

Thanks for your reply and sorry for my late response.
Couple of milliseconds is enough for the SPI Flash that my customer is going to use.
You mentioned LDO_3V3 takes care of any such delay. Could you please explain how it works?

Regards,
Oba

0 Rahul Sharma16 over 6 years ago in reply to Oba

TI__Expert 6430 points

Hi Oba,

The SPI flash is supposed to be power from LDO_3V3 and even the internal core of PD controller is powered from LDO_3V3 and due to boot delays the chip will take some time to reach a point where it will try to access the SPI flash. Therefore, the SPI flash will be power before the PD controller access it.

Thanks,
Rahul

0 Oba over 6 years ago in reply to Rahul Sharma16

TI__Genius 17305 points

Hello,

OK, I understand.
Since POR can’t be controlled externally in this device, my customer would like to confirm POR threshold voltage and reset delay time from the threshold voltage to de-assert internal reset signal to the core.
Are this reset threshold voltage and delay time for internal core available?

Because POR threshold voltage of TPS65981 and SPI Flash could be different. They would like to understand.

Regards,
Oba

0 Oba over 6 years ago in reply to Rahul Sharma16

TI__Genius 17305 points

Hello,

OK, I understand.

Since POR can’t be controlled externally in this device, my customer would like to confirm POR threshold voltage and reset delay time from the threshold voltage to de-assert internal reset signal to the core.

Are this reset threshold voltage and delay time for internal core available?

Because POR threshold voltage of TPS65981 and SPI Flash could be different. They would like to understand.

Regards,

Oba

0 Rahul Sharma16 over 6 years ago in reply to Oba

TI__Expert 6430 points

Hi Oba,

You don't have to, as I said in my previous post. you'll have a lot of time for the SPI flash to get ready and hence won't be any issues later on.

Please click "This resolves my issue" if I was able to answer your query.

Thanks,
Rahul

0 Oba over 6 years ago in reply to Rahul Sharma16

TI__Genius 17305 points

Hello Rahul,

I understand it is not likely to occur any issue,

but my customer just want to confirm for their design verification work. Don’t we have any data?

Regards,

Oba

0 Rahul Sharma16 over 6 years ago in reply to Oba

TI__Expert 6430 points

Hi Oba,

No we don't have any data on this.

Thanks,
Rahul

0 Rahul Sharma16 over 6 years ago in reply to Rahul Sharma16

TI__Expert 6430 points

Hi Oba,

Closign this E2E post as there's no furhter action item on me.

Thanks,
Rahul

0 Oba over 6 years ago in reply to Rahul Sharma16

TI__Genius 17305 points

Hello Rahul,

Sorry for my late response.
I understand we don't have data...

Regards,
Oba

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TPS65981: Period from power-up to starting accessing SPI flash