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SN74LS74A: How to measure the current value

Part Number: SN74LS74A

Hi Team,

I'd like to know how to measure the current value on the datasheet.

When Vcc = MAX and Vi = 2.7 V, the CLK value of IIH is described as Max 20uA.

Please tell me a bit more detailed condition and measuring method.

How does TI measure in the shipping test?

Also, can you offer me a distribution graph at 25°C and a distribution at 75°C for IIH?

Best Regards,


  • Hello,
    Are you having trouble with the input leakage of a device?

    The test conditions for I_IH are VCC = MAX (5.25V) and V_I = 2.7V, as you listed. A DC voltage source of 2.7V is applied to the input under test, and that voltage source will supply some current, which is measured internally by the supply/tester.

    The input leakage is tested on each unit before shipping.

    We do not have input leakage distribution data available for this device.
  • Hi Maier-san,

    My customers are pointed out that there are large current variations at 70℃.

    Is it OK to understand that VI measures the current flowing while inputting to the CLK pin?

    I’m trying to measure because I borrowed an IC that is actually a problem from the customer.

    Best Regards,


  • Hi Ohno-san,
    You will just need a temperature chamber and a supply that can accurately measure the input leakage.

    The supply and ground pins need to be connected - all others are left open.