Created by
Created April 12, 2023
Last modified April 12, 2023
Tags drive   mcu   pnp   zener-diode  


How to drive a PNP (as a switch) from a low voltage MCU I/O port, using only a Zener diode.


To open a circuit with a PNP, we need a voltage at the base close to the voltage at the emitter, and to close the circuit, we need a voltage at the base "far" from the emitter (such as grounding the base).

But how to do it with an MCU only able to deliver 3.3V from its I/O pin, if the load needs, say, around 12 Volt?

A simple solution (that I copied from Cyrob), is to use a Zener diode.

Not convinced? run the simulation and observe that as the MCU goes from 3.3V to 0V, the load get activated.


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