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DP83848 LED LINK not glowing

jaya lakshmi64
Prodigy 90 points

Hi

I am using DP83848 IC with Hx1188 transformer.

RBIAS volatge - 1.2V

PFBIN,OUT1,OUT2 - 1.8V

LED_SPEED, LED_ACT leds are glowing in my board but LED LINK led is not glowing.

what is the reason.

What voltage levels should be there - TD+, TD-, RX+, RX-

I am using 2 PHY chips interfacing with different LPC2388 chips in my custom board, whether i can use

regards

Jaya 

  • 0
    TI__Mastermind 31600 points
    Jaya,

    The RBIAS and PFB voltages are correct. That is a good start. For the next step, I would suggest performing some tests without connecting to a link partner via a cable.

    Please see the E2E post titled "Debug DP83848" at:
    e2e.ti.com/.../805219

    Assuming you have auto-negotiation enabled, the default transmit signaling will be link pulses. Using a short, terminated cable as shown in the post, you can look for link pulses using an oscilloscope.

    Once you have confirmed the link pulse, you can plug a loopback cable into the RJ-45 connector to allow the PHY to link to itself. You should be able to confirm the link via the LED and via the registers.

    Patrick
  • 0 in reply to Patrick OFarrell
    Prodigy 90 points
    Patrick,

    What you have suggested i have tested using loopback cable, the output of the led

    LED_LINK - OFF
    LED_ACT - ON
    LED_SPEED -ON

    what is the reason why LED_LINK is OFF. How to check transmit signalling.

    jaya