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SN74AHC1G14: The customer uses the 3.3v VCC and 5v Vi, does it have problems

Frank Xiao
Genius 12055 points
Part Number: SN74AHC1G14

Hi team,

The customer uses the 3.3v VCC and 5v Vi,  does it have problems? If it has problems, the customer can use resistor divider the voltage. But it may influence the slew rate of the signal. Do you have some recommendation? Thank you.

BR

Frank

  • 0
    TI__Guru* 96862 points

    Hi Frank,

    Short answer

    The SN74AHC1G14 can support up to 7V on the inputs regardless of Vcc, therefore you will have no problems with putting 5V on the input when Vcc = 3.3V.

    Long answer

    This is actually one of our most commonly asked questions in logic.  It isn't very clear from the datasheet what will happen in this case, but there's one place you can get this answer if you know what to look for:  the Absolute Maximum Ratings table.

    The above table is from the SN74AHC1G14 directly.  The line you are interested in is highlighted yellow -- V_I Input Voltage.  Note that the maximum rating is 7 V, while on the next line the maximum rating for the output voltage is V_CC + 0.5V.  If 'V_CC' is included in the maximum specification, then the voltage on that pin is limited by the supply voltage.  If there is no 'V_CC' in the maximum specification, then the voltage on that pin is not limited by the supply voltage.