DP83867IS: Three-Supply Mode - Wait before ramping 1P0

Darren (FAE)

Part Number: DP83867IS

A customer is asking regarding the DPS83867IS.

- Assuming the 2.5V and 1.8V rails are ramped first, is there any maximum time limit before needing the 1.0V rail powered up?

- In other words, if 2.5V and 1.8V are powered and the 1.0V rail is not, will the device experience any kind of breakdown or lifetime degradation?

I don't believe there are any diodes between the 1.0V rail and the others, so I am assuming reverse current isn't a problem...anything else that could happen?

over 6 years ago

0 Vikram Sharma over 6 years ago

TI__Genius 16030 points

Hi Darren,

Yes 1V supply can be ramped up later without issue. Is 1V floating when not powered up?

Regards,

Vikram

0 Darren (FAE) over 6 years ago in reply to Vikram Sharma

TI__Expert 5483 points

Hi Vikram,

The 1V rail to the PHY is powered via an LDO. (have to check which device...).

The LDO has an EN pin. The idea is to wait on powering the EN pin, to keep the LDO output off, until they are ready to power the 1.0V rail.

The LDO internal feedback resistors effectively pull the line to GND, so I don't believe the 1V rail is "floating"...

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DP83867IS: Three-Supply Mode - Wait before ramping 1P0