Sometimes a signal needs to be level shifted when connecting devices operating at different voltages. For example a microcontroller operating at 5.0V and a peripherial device that requires 3.3V.
I had an application where I wanted to shift the 3.3v TX output of an RF module up the 5.0V level used by a PIC microcontroller. Normally I would just have operated the PIC at 3.3V and be done with it. But since the PIC is also connected to a LCD module that requires 5.0V logic levels I needed to keep the PIC at 5.0V and shift the RF TX level up.
Philips/NXP Application Note AN10441 shows how to do this with a FET but I did not have an appropriate FET on hand so I used a General Purpose NPN transistor instead. The level shifter is bi-directional but here I am using it for unidirectional level shifting.
Level Shifting in a Pinch.
Sometimes a signal needs to be level shifted when connecting devices operating at different voltages. For example a microcontroller operating at 5.0V and a peripherial device that requires 3.3V.
I had an application where I wanted to shift the 3.3v TX output of an RF module up the 5.0V level used by a PIC microcontroller. Normally I would just have operated the PIC at 3.3V and be done with it. But since the PIC is also connected to a LCD module that requires 5.0V logic levels I needed to keep the PIC at 5.0V and shift the RF TX level up.
Philips/NXP Application Note AN10441 shows how to do this with a FET but I did not have an appropriate FET on hand so I used a General Purpose NPN transistor instead. The level shifter is bi-directional but here I am using it for unidirectional level shifting.
Here is the working circuit.
Enjoy
William
Last edit: William Roth 2016-06-23