AM4376: DDR_VREF power-up sequence

Sh.Sasaki

Guru 13625 points

Part Number: AM4376

Hi everyone,

Please let me know about the power up sequence of DDR_VREF.

On my customer's board, DDR_VREF rise after 4msec of VDDS_DDR.
Is this sequence correct?

There is no DDR_VREF in the following sequence diagram of DS.

My customer should start DDR_VREF at this timing in this sequence?

Best regards,
Sasaki

over 6 years ago

0 Biser Gatchev-XID over 6 years ago

TI__Guru**** 393215 points

Hi,

This is quite normal, as DDR_VREF is a derivative voltage of VDDS_DDR. There should be no problem.

0 Sh.Sasaki over 6 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your support.

Which timing range of the following sequence should I raise DDR_VREF?

Best regards,

Sasaki

0 Biser Gatchev-XID over 6 years ago in reply to Sh.Sasaki

TI__Guru**** 393215 points

DDR_VREF is not a power supply. It is a reference voltage. There is no timing requirement on the processor side for this voltage. It should ramp-up to nominal value and be stable before the DDR memory is accessed, that's all.

0 Sh.Sasaki over 6 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Biser-san,

Thank you for your support!

I understood it.

Best regards,

Sasaki

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AM4376: DDR_VREF power-up sequence