I've managed to find some ICs which enable level shifting, but none of them have Schmitt trigger inputs. In order to reduce cost and component count, I'd like to ask some of you experienced designers if you are familiar with such a chip.

I found the 74LVC1G17 with maximum Vt+ of 2.79 V which is below my MCU manufacturer's minimum output voltage of 2.9 V. Its counterpart 74LVC3G17 has a totally different specification with a maximum Vt+ of 3.6 V. This made me wonder how the same chip with only a higher number of outputs can have such a different specification.

Of course I will have both 5 V and 3.3 V power supplies available on the same PCB.


1 Answer 1


When powered from 5V, any HCT series logic gate has input levels compatible with 3V3 logic and 5V output levels.

74HCT14 has Schmitt trigger inputs.

74ACT is faster, has higher output current, and makes a lot more noise. Nice cheap way to drive a bunch of 5V MOSFETs from a 3V3 MCU.

  • 5
    \$\begingroup\$ Also 74ACT -- I'm not sure if there's others. There are chips that are specifically advertised as level shifters for other combinations of voltages, but the 74HCT and 74ACT are just perfect for the 3.3V to 5V level shifter task -- I suspect that's the reason no one makes a chip line specifically for that combination. \$\endgroup\$
    – TimWescott
    Aug 21, 2022 at 21:11
  • 2
    \$\begingroup\$ Yes 74ACT has higher output current, useful to drive 5V MOSFETs from a 3V3 MCU \$\endgroup\$
    – bobflux
    Aug 21, 2022 at 21:23

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