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dp83848 mdio low resistance value

jaya lakshmi64
Prodigy 90 points

i have designed lpc2388 with dp83848 .

Both LED_SPEED, LED_ACT leds are glowing but LED_LINK led is not glowing.

I have checked the voltages across RBIAS, PFB.

resistance levels at MDIO is 600ohms with respect to ground.

Whether external pull up resistor is required at MDIO.

LED_LINK not glowing because of MDIO signal.

i have checked MDIO resisatnce in MCB2300 evaluation board is 1kohms.

Only difference i have found this.

regards

Jayalakshmi

  • 0
    TI__Mastermind 23675 points

    Hi Jayalakshmi,

    We recommend a 2.2Kohm pull-up resistor on the MDIO line. A pull-up resistor is required, but the value can have some degree of variance. I am not sure though why the conclusion is that the missing pull-up on MDIO line is causing LED_LINK to not illuminate. 

    Would you mind sharing the schematic? 

    Kind regards,

    Ross