TUSB7340: Sequence of GRST and PERST

Kuan Wei Chen (Kevin Chen)

Genius 9710 points

Part Number: TUSB7340

Dear Team,

Is it acceptable to have the below sequence?

Keivn

over 5 years ago

0 Malik Barton57 over 5 years ago

TI__Guru 64326 points

Hi Kevin,

I do not recommend deviating from the power-up sequence in the datasheet. GRSTz should be deasserted before PERSTz is deasserted.

0 Kuan Wei Chen (Kevin Chen) over 5 years ago in reply to Malik Barton57

TI__Genius 9710 points

Dear Malik

Since we do not find the description of the relation between GRSTn and PERSTn in the datasheet.

Could you provide the delay time from GRSTn to PERSTn and the description of why GRSTn should be deserted before PERSTn.

Kevin

0 Malik Barton57 over 5 years ago in reply to Kuan Wei Chen (Kevin Chen)

TI__Guru 64326 points

Hi Kevin,

There can be some system specific issues if PERST is not controlled separately. GRST and PERST can be connected together and de-asserted at the same time. However, if the customer wants to reset only the PCIe interface through PERST they will also reset TUSB7340 completely through GRST and will need to reconfigure TUSB7340 (as necessary). As for timing, >10us before PERST is de-asserted is sufficient for GRST.

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TUSB7340: Sequence of GRST and PERST