This application note describes a simple technique for implementing a non-inverting buck- boost converter which requires only one inductor. This converter is basically the result of cascading a Buck converter with a Boost converter. This converter can be controlled by two PWM signals from the microcontroller and can provide a 4.2V output from a 5V supply.
This document details a low-cost, non-inverting buck-boost converter design intended for battery charging applications. The circuit utilizes a single inductor and is controlled by two PWM signals generated by an ST7 microcontroller. This topology allows the same hardware to function as a buck converter, a boost converter, or a buck-boost converter depending on the software configuration.
| Control signals | Two PWM signals |
|---|---|
| Gain range | 0 - 200% of input voltage |
| Microcontroller family | ST7 |
The example used is specific to battery chargers, though it is useful for portable applications using rechargeable batteries.
The design requires only one inductor.
The software must ensure that switch SW1 is OFF while switch SW2 is ON.