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TFP410: driving IDCK in differential configuration - missing datasheet perameters

Dan Abbey
Prodigy 590 points
Part Number: TFP410

Hi team, 

Could you please support the below datasheet info request (active project at assigned customer): 

I’m currently looking at the TFP410 Datasheet and in particular about driving the IDCK in a differential configuration. However, it doesn’t seem clear what the thresholds are for the differential setup. It’s clear for the CMOS input type but not for the differential.

I’m looking for the following parameters:

  • IDCK VCM (voltage common mode) – I assume this to be set by Vref on the device
  • IDCK Vih (Voltage In High) 
  • IDCK Vil (Voltage In Low) 
  • IDCK Swing voltage – might be more appropriate

The datasheet is explicit in the CMOS input configuration but not the differential mode. I want to ensure we set the port on the PLD to the correct setting so we don't violate the datasheet specifications, nor introduce marginal stability in the system.

Thanks and best regards, 

Dan

  • 0
    TI__Mastermind 35130 points

    Hi Dan,

    The common mode voltage is set by Vref. For a differential clock the device must be in low signal swing mode (Vref from 0.55V to 0.9V). The input swing in this mode is adjustable from 1.1V to 1.8V.

    Regards,

    I.K.

  • 0 in reply to Ikechukwu Anyiam
    TI__Prodigy 590 points

    Hi I.K. 

    Thanks for the above, after some further discussion with the customer what they really need would be the absolute maximum ratings when used in this mode. The main concern is that it would be difficult to guarantee the voltage while in differential low is always >=0V. On similar devices designed for differential operation you'd usually see an absolute max for the differential low that's negative. 

    Is there something we can share along these lines to provide absolute maximum values to the customer? i guess the easiest way might be to specify it relative to Vref? They'd need values to represent the absolute maximum at differential high / differential low / the common mode voltage. 

    Regards, 

    Dan 

  • 0 in reply to Dan Abbey
    TI__Mastermind 35130 points

    Hi Dan,

    Absolute ratings are provided in the datasheet. The absolute minimum on each pin is -0.5V, which would be -1V differential. Consequently, absolute max would be 4.5V.

    Regards,

    I.K.