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SN74LVC1G08: SN74LVC1G08 / VOH and VOL at Vcc=3.3V

S.Satoshi
Guru 21685 points
Part Number: SN74LVC1G08

Hi,

My customer consider to use SN74LVC1G08 with Vcc=3.3V, so they'd like to know the VOH and VOL spec at Vcc=3.3V. Do you have any information and share it about this spec?

Best Regards,
Satoshi / Japan Disty

  • 0
    Guru 298810 points

    The datasheet shows lower VCC values because no power supply is perfect.

    Your customer's 3.3 V supply might be specified with a tolerance of ± 10 %, and even if there is no such specification, it will have some irregularity in practice.
    So for the worst case, you actually need to use the VCC = 3 V values.

  • 0
    TI__Guru* 97017 points

    Hello Satoshi-san,

    Clemens is correct. It is definitely best to design for the worst case scenario.

    If you really need to know the VOH for a particular VCC value, you can use some simple math to get a reasonable estimate. Note that the voltage drop at the output at 3V is 0.6V (3V - 2.4V) for IOH = -16mA and 0.7V (3V - 2.3V) for IOH = -24mA. This voltage drop is caused by the FET driving the output, and can be used to generate an estimate at other voltages.

    Since FET resistance is inversely proportional to VCC, you can assume the voltage drop will be less at higher VCC values. At 3.3V, the VOH can be estimated as 3.3V - 0.6V = 2.7V for IOH = -16mA, and 3.3V - 0.7V = 2.6V for IOH = -24mA.

    Please note also that, in the majority of systems, logic only supplies a few microamps during operation, and the VOH is typically very close to VCC (and VOL is typically very close to ground).