Re: [EE] Logic level conversion and power consumption

On 29 Apr 2026 at 23:43, Sean Breheny wrote:
<snip>

> Unfortunately the chips I was using in the 74LVC family have no drop-in
> equivalent in HCT logic so I need to add an additional level conversion
> stage.

Maybe if you're lucky there will be a Schmitt trigger version in 74LVC. To be honest 
still not 100% sure if this will solve your current consumption problem or not, but 
curious to know.

> Anyone run into this before?

Recently designed a circuit for a 3.3V uC to handle signals to and from digital 
sensors that had to not care if the sensors were 3.3 or 5V. Oddly turned out to be 
slightly more dificult/elaborate than I expected.

Went with 74HCT2G17 Schmitt trigger running on 5V, didn't measure crossover 
current as you have but fortunately not a big concern in my application. In one 
direction converts 3.3 or 5V sensor signal to 5V signal then through resistor divider 
to 3.3V uC input. Other direction 3.3V uC output becomes 5V signal out of the 
74HCT2G17 directly drives a P-Ch MOSFET to switch 5V for 5V sensors, same 
signal resistively divided to 3.3V to drive a P-Ch MOSFET to provide 3.3V for the 
sensors that require it. 

On top of that it was harder than I thought it would be to find the right chip in the 
right family in the package in stock. Bought extras so it should be less of a problem 
next time :-)