Linear Voltage Regulator vs. Buck-Boost (Step Up/Down) Converter for Bike Powered USB Charger

Thread Starter

AdelCraft

Joined Jul 9, 2020
2
Hi,

I am making a bike powered USB charger. The output must be 5V@2.1A. Considering that the wheel won't have a constant speed, what is the best way of regulating the output voltage? As I know that a linear voltage regulator will make much more losses of energy in heat, I wanted to use a buck-boost (step up/down) converter, but every tutorial I found on internet for similar projects were using a linear voltage regulator.

What should I use?

Thanks.
 

dendad

Joined Feb 20, 2016
3,564
First, what is your generator voltage and current capacity?
If it will only output around the required voltage , then a linear will be ok. But if it will supply a fair bit higher, go switch mode.
For instance, if it is 12V out, a linear will waste almost 2/3 the power generated in heat. It is hard enough riding a bike without having to add extra wasted load to your effort.
Just a buck would be ok if your normal riding speed produces enough volts.
 
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