DP83867CR: VDD1PD goes up when VDDIO ramp up

Katsu Matsunaga

Expert 7730 points

Part Number: DP83867CR

Hello,

I would like to ask you check a power sequence of target board.

VDD1PD goes up around 200mV when VDDIO ramp up. There is no sequencing requirement of VDD1PD and VDDIO.

Is this problem?

It looks VDDIO supply current leaks to VDD1PD.

Could you please give your advise?

Best regards,

Katsu

over 5 years ago

0 Geet Modi over 5 years ago

TI__Mastermind 26320 points

Hi Katsu-san,

their is always interaction of digital circuitry with IO and may be causing this. Are you observing any system level issue ?

Regards,

Geet

0 Katsu Matsunaga over 5 years ago in reply to Geet Modi

TI__Expert 7730 points

Hi, Geet-san,

Thank you for your reply.

No, the system level issue has not been observed.

Is this phenomenon expected?

Best regards,

Katsu

0 Vikram Sharma over 5 years ago in reply to Katsu Matsunaga

TI__Genius 16030 points

Hello Katsu-san,

Is VCC1_8V (ch4) the IO supply you are referring to?

Regards,

Vikram

0 Katsu Matsunaga over 5 years ago in reply to Vikram Sharma

TI__Expert 7730 points

Hi Vikram-san,

Yes, VCC1_8V is IO supply as VDDIO.

Best regards,

Katsu

0 Vikram Sharma over 5 years ago in reply to Katsu Matsunaga

TI__Genius 16030 points

Hi Katsu-san,

Yes ramp of vdd1p0 alongside vddio is expected ( when vdd1p0 is floating). There is a weak leakage path from VDDIO to VDD1P0 which ramps up VDD1P0 along side VDDIO ramp. But the final floating value of VDD1P0 will be very low (as seen in your plots).

Regards,

Vikram

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DP83867CR: VDD1PD goes up when VDDIO ramp up