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SN74LS73A: Input current

Danilo A.
Mastermind 30960 points
Part Number: SN74LS73A
Other Parts Discussed in Thread: CD74HC73

Hi Team,

A customer is asking for the input current of SN74LS73A. Does IIH and IIL at page 4 of the datasheet represent input current high and low respectively? If yes, why is the IIL of CLK a negative value? Do we have the values of the input current when the input voltage is 0V and 5V?

Regards,

Danilo

  • 0
    Guru 318760 points

    The values for the LS device are shown on page 5.

    II, IIH, and IIL are the input currents. Positive currents flow out of the pin; negative currents flow into the pin.

    For 5 V, you can use the the 5.5 V value (it's just the leakage current through the diodes).

    For 0 V, the voltage drop over Req is slightly larger (see p. 2), so use the 0.4 V value multiplied by (5 V / 4.6 V). The datasheet specification is for 0.4 V because that is the voltage of a low LS output.

    If the device is to be used with CMOS input signals, why not use the CD74HC73?