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SN74LVC2G07: SN74LVC2G07 5V VIH Pull Up Resistor 33.2Kohm

Cheney_Sun
Intellectual 595 points
Part Number: SN74LVC2G07

Hi TI EE：

               SN74LVC2G07，VCC:5V。Vin Pull Up Resistor is 33.2Kohm and Pull Up Voltage is 5V.Please help to make sure if that 33.2Kohm Pull Up resistor can meet the buffer normal operating.

            

Regards

Cheney_Sun

              

  • 0
    TI__Guru* 97046 points
    Hello Cheney,
    I'm not sure what you want me to do here.

    You haven't showed me the source of 5VREFA, so I don't know if it can source enough current to support the 33.2kohm resistor.

    I don't know where the signal is coming from for pin 3 of the SN74LVC2G07, so I can't comment on the input voltages.

    The parasitic capacitance on pin 3 is unknown (is that wire 3 meters long of 50 ohm coax or 2mm of trace? I have no idea from the above image...)

    The output load isn't shown, so I can't comment on the signal integrity.

    ***

    All I can tell you for certain is that:
    (1) The SN74LVC2G07 has a maximum input leakage current (DC) of 5 μA, which will produce a drop of 166mV across the 33.2k ohm resistor. By itself, this is not a problem for the SN74LVC2G07.

    (2) The output of the SN74LVC2G07 will easily support the DC curent from the 4.75kohm resistor from the (presumably) 3.3V supply. Using ohm's law to get a ballpark current: I = V/R = 3.3/4750 ~= 0.69 mA -- the SN74LVC2G07 can support up to 32mA at the output, so there's no problem there.