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TCA6408A: Pin Capacitance

Shinu.V.Mathew
Expert 7465 points
Part Number: TCA6408A

Hi Team,

Can you plaese help with Pin capacitance (Cin) of RESET pin.

Regards, Shinu Mathew.

  • 0
    TI__Mastermind 49370 points
    Hello Shinu,

    I believe the capacitance should be about 10pF.

    I've ordered some samples so I can check when they get here.

    Thanks,
    -Bobby
  • 0 in reply to BOBBY
    TI__Mastermind 49370 points

    Shinu,

    I connected the device to a mosfet pulling low on the Reset pin and then releasing allowing a pull up resistor (444 ohms) to pull the signal up to Vcc (3.3V). I measured the 30% time value and 70% time value and looked at the difference which I call the rise time.

    Capacitance = t_rise/(0.8473*pullupresistor)

    Measurement of just my set up below (no device connected)|| capacitance comes out to 343pF

    Measurement of just my set up below (with reset pin connected)|| capacitance comes out to 332pF

    The difference between the two is about ~11pF. Some of this capacitance is from a long trace of the breakout board I was using (approximately 2inches in length).

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Expert 7465 points
    Thanks Bobby.