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DS90UB948-Q1: How to fix 948 EQ

Rocson He
Intellectual 1830 points
Part Number: DS90UB948-Q1

Hi Experts,

Could you help share with us, for DS90UB948, does it share the same EQ level setting as the table 4 at the 954/96X app-note  as below link?

Thanks.

 

1. That is, to take one example, to fix 948 EQ at level 1, should we just set 0X44=0X11 (using EQ stage 1) ? And other register need to be set ?

2.  For 948, is the SP need to be set as 95X/96X ? And what register do we need to program, as the app-note only share the indirect SP register for 95x/96x ?

www.ti.com/.../snla301.pdf

 

  • 0
    TI__Mastermind 19720 points

    Hi Rocson,

    Why are you trying to modify the strobe position and AEQ values of the 948?

    We do have a MAP tool for the 948 if that is what you are looking for: 

    Regards,

    Michael W.

  • 0 in reply to Michael.Walker
    TI__Intellectual 1830 points

    Hi Michael,

    Customer is doing the MAP as recommended and introduced based on the MPA note on-line(you also shared just now above), and find that the MAP result is not good(green/pass) in all EQ and SP setting, and only lower EQ level could make the panel work normally, while higher EQ could make the panel lose lock and jittering.

    So they would like to fix the EQ at level 1 or 2, based on the result, and with margin around these level setting.

    But we don't know how to correcting map the EQ stage 1 and EQ stage 2, and how to set the 0X44 correctly, as there is no detailed register and table mapping for 948 at the app-note on-line. (The note only with registers details for 95X and 96X)

    So they ask below two questions, could you please help feedback with details accordingly ? 

      1. That is, to take one example, to fix 948 EQ at level 1, should we just set 0X44=0X11 (using EQ stage 1) ? And other register need to be set ?
      1. For 948, is the SP need to be set as 95X/96X ? And what register do we need to program, as the app-note only share the indirect SP register for 95x/96x ?

    Thanks.

    Rocson

     

  • 0 in reply to Rocson He
    TI__Guru** 107510 points

    Hello Rocson,

     

    if increasing the EQ value results in quality issues, that means you have a lot of reflections (Impedance unmatched) on your board. To solve this issue you need to improve the Impedance matching (S11).

     

    We normally do not recommend fixing the EQ value, because AEQ is there to help your system compensate the cable aging problems.

     

    To bypass the Adaptive Eq and fixe EQ to 1:

    c) Set Bit 0 of Reg0x44

    d) Choose the correct setting of the EQ on EQ Stage1 (Reg 0x44[7:5]) = 1