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SN74LVC16244A-Q1: How can to calculate the maximum current?

Charles Jeon
Expert 2975 points
Part Number: SN74LVC16244A-Q1

Hi Team.

My customer required that how can to calculate the maximum current.

I checked the datasheet because I think that the current will be the maximum when all outputs are on.

I don't understand what the status of IOH and IOL is.

Please check that the maximum current calculation I calculate is correct.

(IOL * 16ch) + (Icc * 4ch) = (20mA * 16 ) + (20uA + 4) = 320.08mA

Thank you!

  • 0
    Guru 272340 points

    What exactly is meant with "maximum current"?

    What the chip itself will take is specified by ICC. This is 20 µA for the entire chip.

    The leakage current of each digital input is specified by II. So for 20 inputs, you'd get at most 100 µA.

    The current through each output depends on whatever loads are connected to the outputs. In any case, the load current flows out of VCC or into GND, so the sum of all currents must be limited to the value specified in the absolute maximum ratings, i.e., 100 mA for either VCC or GND. (You can get 100 mA through VCC and 100 mA through GND if some outputs are high and some are low.)

    There is no IOL specification. The datasheet specifies a maximum voltage drop for a specified current, but you can use a higher current if you can tolerate a higher voltage drop. The current per pin is limited only by the absolute maximum rating IO of 50 mA.

  • 0 in reply to Clemens Ladisch
    Expert 2975 points

    If then all ports are used, is the total current consumption of the chip itself 120uA?

    Even load is connected to all outputs, does it mean that the sum of all ports current on ic can not exceed 100mA?

  • 0 in reply to Charles Jeon
    Guru 272340 points

    There are three different specification because the current flows differently. ICC flows out of VCC, through the chip, and into GND. The input leakage current flows either out of VCC and out of the input, or into the input and into GND. The output load current flows either out of VCC and out of the output, or into the output and into GND.

    So what do you mean with "total current consumption"? The current flowing out of VCC, or the current flowing into GND, or both of them? (Please note that the leakage and load currents also flow through VCC or GND of the connected devices.) In practice, you have to measure the total current consumption of the entire system.

    When all outputs have the same logic level, their total current indeed must not exceed 100 mA.