DP83867IR: Power Down Sequence Timing in Three Supply Mode

Hello Jason Haedt,

Thank you for the query.

Please refer to section 10 Power Supply Recommendations

When operating in three-supply mode, the 1.8-V VDDA1P8 supply must be stable within 25 ms of the 2.5-V VDDA2P5 supply ramping up. There is no sequencing requirement for other supplies when operating in three supply mode.

When powering down the DP83867, the 1.8-V supply should be brought down before the 2.5-V supply.

Regards,

Sreenivasa

Yes, this is exactly my question from the datasheet.  The datasheet just states that the 1.8V should be brought down before the 2.5V but doesn't specify any timing or voltage differential that needs to be maintained.  My 1.8V rail has more capacitance so it will start coming down before the 2.5V supply but I don't have an additional enable to wait until the 1.8V hits zero before disabling the 2.5V.  

Hello Jason Haedt,

Thank you for the reply.

(+) DP83867IR: Power down sequence - Interface forum - Interface - TI E2E support forums

Would you be able to capture a plot and share to verify.

Regards,

Sreenivasa