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TLK110 Auto Nego Issue

Elvis Wei
Intellectual 320 points
Other Parts Discussed in Thread: TLK110

Hello,

The TLK110 is not able to establish link after auto nego funection(set bit 12 = 1 (auto-neg enable) and bit 9 = 1 (restart auto neg) in BMCR register).

However, a valid link (10MBaseT) established successfully while preform a forced modes and run a MII loopback test.

Is that any clue how to address the auto nego fail issue.

One thing may be related, the pin LED_SPEED/AN_1 is not connected(NC),  and the LED_LINK/AN_0 pin and the LED_ACT/AN_EN pin connect to corresponding LED only( no 2.2k resistor connect to GND or VCC ).

Thanks you,

Elvis

  • 0
    TI__Mastermind 31600 points

    Elvis,

    I have a few suggestions and questions below.

    Please replace inductor L4 with a 0 Ohm resistor.  The de-coupling caps for the AVDD33 supply appear to be too small to provide solid supply characteristics without a direct connection to the main 3.3V supply. 

    You have confirmed that a link can be achieved by forcing the device to operate in 10M mode (BMCR:0100).  Could you also try:

    1. Auto-negotiation to 10M mode (ANAR:  0061, BMCR:  1200).  Note that it is best to re-start auto-negotiation after changing the advertisement register.
    2. Force 100M mode (BMCR:  2000).  Note that this will result in a half-duplex link.  I am assuming that the link partner is configured for auto-negotiation and auto-MDIX such that it will be able to parallel detect the link.

    Patrick

  • 0
    TI__Intellectual 1885 points

    Hello,

    In addition to enabling Auto-Neg in the BMCR register, you also need to make sure that the ANAR register(04H)is set to advertise the desired speed. You also need to ensure that your link partner is set to support Auto-Neg and that it is also advertising the correct speed.

    Thanks,

    John

  • 0
    Intellectual 320 points

    Many thanks to both of you, Patrick and John for the help.

    The auto-negotiation established with a 100MBaseT link successfully while replacing the inductor L4 to a 0 Ohm resistor.

    One thing should be noticed that the pin AVDD33 is the same voltage ( 3.35v - 3.36v ), either with the inductor L4 or 0 Ohm resistor, but the result was totally different?

  • 0 in reply to Elvis Wei
    TI__Mastermind 31600 points

    Elvis,

    Depending on the operational mode of the device and the equipment that you use to measure the AVDD33 voltage, it is quite possible that you measure the same DC voltage with or without the inductor.  The key here is that the current drawn by the TLK110 is not purely DC. 

    When the TLK110 is transmitting and receiving 125MHz 100Base-T signaling, current demand in the device will occur at those higher frequencies.  If the inductor prevents the device from meeting those current demands, the device will not be able to function as necessary.

    Patrick