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DS25MB100 Intput issue

mars chuang
Prodigy 130 points
Other Parts Discussed in Thread: DS25MB100

Hello

I have some questions about DS25MB100

If output will send two kinds of signals , 

HS mode: 200 mV (Vp-p)

LP mode: 1.2V single-end

Can DS25MB100 receive it directly ?

What is the output voltage level of the single-end ?

  • 0
    TI__Mastermind 29635 points

    Hi Mars,

    Both modes you mention above are possible for use with the DS25MB100 if you use AC coupling on both input and output. HS mode works since the Vpp voltage is within the acceptable datasheet limit. LP mode is more complex. If you AC couple at the input, the 1.2 V single-ended input will appear to the DS25MB100 as a 1200 mVpp signal centered around 0 V (i.e. +/- 600 mV amplitude) on one input. Since there is 0 V present on the other input, the resulting differential signal will be within the 100-1560 mVpp input signal requirements.

    The output voltage level is set at approximately 1200 mVpp without pre-emphasis. When I measured a single-ended PRBS signal with 1.2Vpp, the Vpp voltage around 1050 mVpp. The zero-crossing of the eye appears offset, and I attribute that to driving an output from a signal that is not truly differential:

    Are you AC-coupling these inputs to the DS25MB100?

    Thanks,

    Michael