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SN65LBC172A propagation delays

mahmut turk
Intellectual 300 points
Other Parts Discussed in Thread: SN65LBC172A, SN65HVD75, SN65LBC173A

Hello all,

I want to know if the propagation delays given in the datasheet of SN65LBC172A are common/same for all 4 channels. For instance, if delay for the first channel is measured as 10ns, is the same delay value 10ns for the other three channels? I intend to use this ic for synchronous communication, so the delay between channels (channels will be used as data and clock) is so important. 

Thanks.

  • 0
    TI__Guru 62910 points

    Hello,

    The propagation delays are not guaranteed to be exactly the same - there can be up to 2 ns of difference between channels of a given device.  This is what is referred to as "output skew" in the datasheet's switching characteristics table.

    Best regards,
    Max

  • 0 in reply to Max Robertson
    Intellectual 300 points

    Thank you Max,

    As far as i understand, using two ics such as sn65hvd75 to transmit a synchronous signals at 20mbit (data and clock, one ic for data, one ic for clock) is not so reliable since propagation delay values in datasheet show that delay values may vary from one ic to another.

    However using 4 driver and 4 receiver pair differential drivers such as sn65lbc172a and sn65lbc173a in sending synchronous signals will work since both data and clock signals wil be sent using only one ic and channel to channel delay skew is only 2 ns.

    Am i correct Max?     

  • 0 in reply to mahmut turk
    TI__Guru 62910 points

    Yes, when trying to keep propagation delays similar for each signal it is best to use a one multi-channel IC.  Otherwise, normal process variation can result in some differences from unit to unit.

    Max