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DS125BR401A: The signal seems to be over de-emphasis after passing the DS125BR401a

Lacey Lin
Intellectual 2900 points
Part Number: DS125BR401A


Hi team,

My customer use the DS125BR401a to drive the SATA 6G signal.

In the system, the SATA signal will go through the RAID card----1.5m cable--3inch PCB trace---DS125BR401a----10inch PCB trace---HDD

They use the channel 7 and set the register as below：

0x41=0x2f

0x42=0xaf

0x43=0x00

But the eye of the SATA signal is not good. Show as below:

Can you help to reply below question:

1. Can the DS125BR401a support the application?

2. Does this eye shows the signal has been over DE?

3. For the channel A, it seem we can't adjust the DE as channel B. When we set the DE to 0x00, does it means the DE is the weakest?

4. Can you help to analysis what maybe the cause for this bad eye diagram?

Lacey

Thanks a lot!

  • 0
    TI__Mastermind 43795 points

    Hi Lacey,

    I would try to reduce the equalization on this channel by one setting. 

    Currently 0x41=2F

    New 0x41=2E

    The linear channels on the DS125BR401A A-side are not able to generate de-emphasis on their own, the signal overshoot is likely caused by an EQ setting that is just a little higher than needed.

    Regards,

    Lee