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DP83TC811R-Q1: Link down during high temperature testing

Wenting Wu
Intellectual 2190 points
Part Number: DP83TC811R-Q1
Other Parts Discussed in Thread: DP83TC811

Hello Expert,

The customer did high temperature testing for DP83TC811R-Q1 and there was a link-down issue happen. After checking the register value, only 0x0017 becomes different. When error happens, the register is shown as the left picture and when correcting this register to be like the right picture, the link-down issue can be removed. 

Could you give me some ideas on it?

Thank you very much.

Best regards,

Wenting 

B

  • 0
    TI__Mastermind 19521 points

    Hi Wenting,

    Could you read Reg 0x467 before and after the problem to see if it's a strapping issue?

    Please note that this is an extended register and requires special steps to read.

    Please refer to Table 25 in Section 8.6.1 Register Access Summary in the SNLS579A 811 Datasheet for how to read this register.

    Regards,

    Alvaro

  • 0 in reply to Alvaro (Al-vuh-roe) Reyes
    TI__Intellectual 2190 points

    Hello Alvaro,

    The 0X467 register is always read. we looked at the record, and there was no change here, and it was 000C all the time, but we didn't know whether it was correct. Need help from your side to check whether only RX _ D2 is 11 and  everything else is 0 are correct or not. 

  • 0 in reply to Wenting Wu
    TI__Mastermind 19521 points

    Hi Wenting,

    I don't have sufficient information to answer this for you. Compare this 0x000C Value with Section 8.5 Programming in the SNLS579A Datasheet. Register 0x000C should match how the PHY is strapped.

    If they don't then we need to look at how each bootstrap pin was Pulled Up/Down.

    Regards,

    Alvaro

  • 0 in reply to Alvaro (Al-vuh-roe) Reyes
    TI__Intellectual 2190 points

    Hello Alvaro,

    • May I also ask the principle of LINK-DOWN for DP83TC811? For example, in which situation, the LINK-DOWN will happen.
    • For high temperature testing, the customer can exclude strapping issue with reading 0x467 register. Could you give us some ideas on other reasons may cause link-down in high temperature testing and how to exclude? There is a strange phenomenon that if the customer rise temperature from low to high, the link-down will happen while if the temperature is high in the beginning and keep in this high temperature or drop the high temperature to low temperature, the issue will not happen. 
    • Beside of high temperature testing, the customer also met link-down in pressure testing. The customer reset power in thousands times, and there will be link-down happening. 

    Best regars,

    Wenting 

  • 0 in reply to Wenting Wu
    TI__Mastermind 19521 points

    Hi Wenting,

    I missed it earlier but it seems like the PHY is NOT Losing Link.

    Reg 0x0001, bit 2 tells us there is still link.

    Could you share your schematic and a picture of the top marking of the 811 Device?

    Regards,

    Alvaro