XIO2001: Power-up Sequence, PCIR

Oba

Part Number: XIO2001

Hello,

I have read the below similar thread.

http://e2e.ti.com/support/interface/digital_interface/f/130/p/670163/2466816

In this thread, 1.5V and 3.3V sequence is discussed and there is no sequence requirement for them.

Then I have a question for PCIR and 1.5V/3.3V power-up sequence.

The datasheet requires removing PICR first, then 1.5V/3.3V removing for power down like the below.

But the datasheet doesn't mentioned about PCIR and 1.5V/3.3V relation for power-up like the below.

So my question is how to think about PCIR sequence for power-up?
From Figure 4, it looks 1.5V/3.3V/PCIR are not require any special sequence for power-up.
But from Figure 5, it looks also not to require any special sequence, but PCIR first removing is required of power-down.

Regards,
Oba

over 6 years ago

0 Malik Barton57 over 6 years ago

TI__Guru 64326 points

Oba,

PCIR should come up in step 2 of the power-up sequence for XIO2001. Since this voltage helps to protect the I/O pins of XIO2001, PCIR should be applied before the PCI bus is active.

0 Oba over 6 years ago in reply to Malik Barton57

TI__Genius 16125 points

Hello,

Thanks for your reply.
Is there any power up sequence between 1.5V/3.3V and PCIR in step 2?
Because power-down sequence requires PCIR removing before 1.5V/3.3V removing.

Regards,
Oba

0 Malik Barton57 over 6 years ago in reply to Oba

TI__Guru 64326 points

Oba,

No there is not a specific power-up sequence between 1.5V/3.3V and PCIR. Follow the link below to XIO2001 EVM user guide to see how PCIR can be implemented (See figure on Page 10).

0 Oba over 6 years ago in reply to Malik Barton57

TI__Genius 16125 points

Hello,

I may not understand about PCIR well,
but could you tell me why PCIR removing is required before 1.5V/3.V removing while power-up doesn't require any sequence for these 3 rails?

Regards,
Oba

0 Malik Barton57 over 6 years ago in reply to Oba

TI__Guru 64326 points

Oba,

The function of PCIR is to protect internal I/O cells in XIO2001 PCI bus from excessive input voltage. For power up the order is not necessary because device is not "ON" until GRST is asserted. During power-down, removing PCIR before 1.5V/3.3V is required to ensure that I/O cells of XIO2001 PCI bus are "OFF" then main power can be ramped down.

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XIO2001: Power-up Sequence, PCIR