DP83848I: Internal circuit of RESERVE pin

na na78

Guru 16770 points

Part Number: DP83848I

The customer has questions for RESERVE pin (PIN20, PIN21).

Could you please answer followings?

According to datasheet, these pins must be pulled up through 2.2K resistor to AVDD33.

Why isn't it allow to connect these pins to GND or leave them float?

The customer want to leave pins open if possible.

What impact could it be considerable if these are open?

BestRegards

over 6 years ago

0 Rob Rodrigues over 6 years ago

TI__Mastermind 19780 points

Hi na na,

There is detect functionality in the reserved pins 20 & 21 that could put the PHY into an undefined operational state. An old function was planned, but never implemented, and this function must not be enabled.

So the reserved pins MUST be pulled up to AVDD33.

Best Regards,

0 na na78 over 6 years ago in reply to Rob Rodrigues

Guru 16770 points

Hi Rob

Thank you for your reply.

The customer asked one more question.

Additional questions:

RESERVED pins are defined as input/output.

Is there a way to set RESERVE pin as output by register control? (e.g. by using MDIO)

BestRegards

0 Rob Rodrigues over 6 years ago in reply to na na78

TI__Mastermind 19780 points

Hi na na,

The I/O nature of the pins cannot be changed.

Best,

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DP83848I: Internal circuit of RESERVE pin