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SN74LVC1G3157: Input capacitance value in datasheet and IBIS model

Part Number: SN74LVC1G3157
Other Parts Discussed in Thread: TMUX1248,

Hello Team,

My customer is designing SN74LVC1G3157DRYR. 

For input capacitance value, the value only for 5Vcc condition appears in datasheet. Could you let me know the value for other Vcc?

I expect that I may be able to find those values in IBIS model. But it looks the model does not even contain the value for 5Vcc as below. Is this a corresponding parameter to Ci in datasheet?

Thanks,

  • Hey Ella,

    The Vcc won't have much of an impact on this at all. You should expect to see close to 2.7pF input capacitance on the select pin independent of the Vcc condition.
    That being said, the IBIS model does actually show this capacitance. The current model you're looking at is the IO switch capacitance. The control input is labeled as  "LVC1G3157_IN" which the voltage value appended for the Vcc voltage condition it's being modeled at. So for example, the model for the control pin at 1.8V will be labeled "LVC1G3157_IN_18".




    Additionally, have you taken a look at the TMUX1248? it's a newer part that is a drop in replacement for the SN74LVC1G3157. If input capacitance is of concern, the TMUX1248 has a lower spec there. The 1248 has 1.8V logic compatible, has a lower Ron and has integrated fail-safe logic. Additionally it will save on overall power consumption; At 5V @ 25C the 3157 supply current is 1uA typical vs 0.007uA typical for the 1248 part. 

    Thanks,
    Rami