TUSB8043A: Power up timing

Kei Kuwahara

Expert 4870 points

Part Number: TUSB8043A

Hello team,

On the datasheet, it says "there is no power-on relationship between VDD33 and VDD".

But can I power up VDD33 before VDD? The Figure 1 looks like VDD is powered up before VDD33.

Best Regards,
Kei Kuwahara

4 months ago

0 Brian Zhou 4 months ago

TI__Guru** 111500 points

Hi Kei:

GRSTz is pulled up to 3.3v internal, so it will follow 3.3v. Suggest 1.1v is powered up before 3.3v or power up same as 3.3v.

Regards

Brian

0 Kei Kuwahara 4 months ago in reply to Brian Zhou

TI__Expert 4870 points

Hello Brian-san,

The customer has found this statement from the datasheet.

"The core power (VDD) or I/O power (VDD33) may be powered up for an indefinite period of time while the other is not powered up if all of these constraints are met"

Why can't 3.3V be powered up before 1.1V?

Best Regards,
Kei Kuwahara

+1 Brian Zhou 4 months ago in reply to Kei Kuwahara

TI__Guru** 111500 points

Hi Kei:

You can power up 3.3v before 1.1V, but you need to make sure GRSTz is up after both 3.3v and 1.1v stable.

Regards

Brian

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TUSB8043A: Power up timing