SN74LVC8T245: Output stage question

Hi Gregory,

This is a common use case with logic. https://training.ti.com/TLM-APP-DrivingLED?cu=1134826

Please watch this video to size your resistor properly if you have not already done so but yes this should work.

Thanks!

-Karan

When the A input is high, the B output is at 5 V, so the voltage drop over the diode is zero (not negative).

To get a reverse bias, you would have to switch not only the cathode high, but also the anode to a lower voltage.
Is it actually necessary to have a reverse bias?

The forward voltage of the IR LED is so low that you do not actually need 5 V; you could drive it from 3.3 V (if you have the drive strength). Using the SN74LVC8T245 for this makes sense only if you are already using it for other purposes, and have some channels left.