DP83826E: 49.9 pullups required or not on RD_M RD_P TD_M TD_P pins

thierry Didi

Part Number: DP83826E

Dear TI team,

I have designed a board with DP83826E Ethernet PHY connected to a PULSE-HX1198FNL transformer. In some previous designs with some TI microcontrollers or with Microchip ENC28J60, I used to implement some 49.9 ohms pullups on TX and RX pins.

I cannot see this pullups in DP83826E datasheet, nor in the schematics of the 83826EVM.

I am not expert in this area, and I would like to confirm if I really don't need these pullups on these pins (RD_M, RD_P, TD_M TD_P)

Many thanks

Thierry

over 4 years ago

+1 David Creger over 4 years ago

TI__Mastermind 28642 points

Hi Thierry,

Confirmed. You do not need the 49.9 ohm pullups on the RD_M, RD_P, TD_M, TD_P pins.

The DP83826 utilizes a voltage mode driver, while some previous PHYs had used current mode drivers which required pullups.

Thanks,

David

0 thierry Didi over 4 years ago in reply to David Creger

Intellectual 410 points

Many thanks, it's clear.

Thierry

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DP83826E: 49.9 pullups required or not on RD_M RD_P TD_M TD_P pins