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DS90UB954-Q1: Equalization setup

Part Number: DS90UB954-Q1

Hello,

My customer wants to achieve best performance of AEQ even though lock time gets longer.

Could you provide AEQ register configuration to get best AEQ performance?

Customer uses coax cable with 2m length.

Best regards, 

  • Fujihara-san,
    Please refer to the DS90UB954 datasheet AEQ for details. Section 7.4.9 provides information on AEQ range and timing and how to set MIN and MAX value.

    The lock time (deserializer data lock time tDDLT in section 6.6) varies based on the AEQ full or partial range. For a short cable/lower insertion loss, the lower AEQ values would be more optimal and limiting to those values will also reduce the lock time.
  • Manickam-san,

    Thanks a lot for your prompt response, I checked the datasheet.

    Now the customer would like to bypass AEQ and configure EQ_STAGE_1 and EQ_STAGE_2 manually.
    Could you provide information how to configure EQ_STAGE_1 and EQ_STAGE_2 of ADAPTIVE_EQ_BYPASS Register?
    It looks no further information for those parameters.

    Is there relation between EQ_STATUS[5:0] of AEQ_STATUS register and EQ_STAGE_1/ EQ_STAGE_2 of ADAPTIVE_EQ_BYPASS Register?

    Best regards,
  • Fujihara-san,
    It is better to let it auto adapt instead of fixing the EQ value manually so it can track the voltage/temperature variations and aging of the cable over time and re-adjust the optimal value as necessary.
    Since their cable loss is minimal, it should be ok to limit to lower AEQ values, say between 0 and 2. This can be set via the AEQ_MIN_MAX register 0xD5. For eg to set MIN to 0 and MAX to 2, set register 0xD5 = 20.
  • Manickam-san,

    Thanks for your reply.

    This time, manual setting requiremnt is only for EMI measurement purpose.

    So could you provide information about EQ_STAGE_1_SELECT_VALUE and EQ_STAGE_2_SELECT_VALUE ahd procedure how to configure these parameters correctly?

    Of course, for actual application use, I recommend to use AEQ not manual EQ.

    Best regards

  • Fujihara-san,
    Let the AEQ adapt and read the adapted value through reading register 0xD3[5:0] and this value can be written into 0xD4 EQ_STAGE_2[7:5] and EQ_STAGE_1[3:1] for manual setting. Keep in mind when setting EQ manually 0xD4[0] should be set to '1' to disable the adaptive EQ.

    0xD3 will give an indication if the cable loss varies over time. This is expected to remain very consistent for a particular cable such as the 2m they're using under nominal conditions.
  • Manickam-san,

    Thanks for you reply.

    Let me confirm, as a starting point,is it correct with following setupt?

    EQ_STAGE_1_SELECT_VALUE = EQ_STATUS[5:3]

    EQ_STAGE_2_SELECT_VALUE = EQ_STATUS[2:0]

    ADAPTIVE_EQ_BYPASS = '1'

    Best regards,

  • EQ_STATUS bits [5:3] should map to EQ_STAGE_2 value and bits [2:0] to EQ_STAGE_1.
    You're correct ADAPTIVE_EQ_BYPASS should be '1' when setting EQ value manually.