9V to 5V conversion problems

Hello. I wanted to build a circuit operating at 9V with a microcontroller operating at a maximum of 5.5V. Will it be okay if I use a voltage divider to power it? Thank you in advance for your help

by Lionsio
November 12, 2024

Probably no. If you place the MCU in parallel with one of the resistors, you need small resistors so the the resistivity of the MCU in parallel with its resistor won't change much if the resistivity of the MCU changes. That means that you will lose a lot of energy through the small resistances.

But consider too that the MCU may not require a constant current and if it requires a large amount of it, you don't have a voltage divider anymore since it is not the same current running trough both resistors anymore. So your supplied voltage to the MCU may varies and invalidate some of its components, due to these fluctuations.

I will try a TL431 instead, if your MCU don't ask for more than 100mA. The TL431 is a kind of Zener diode that you can specify its Vz value (with a nice sharp knee) by adding few components to it. See its datasheet.

by vanderghast
November 14, 2024

Thanks for 101 games post!

by Hismandent
November 18, 2024

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