During the development of the Arduino USB Host Shield, I designed a small and simple boost converter to provide 5V to the VBUS line from a 3.3V input. The circuit, built around Linear Technology’s LTC3426, performed so well that I decided to release a standalone version. There are many uses for such a converter—providing LCD contrast bias is one of the most common. Another scenario where a 3.3V-to-5V converter can be useful is with older Arduino shields. This photo shows my converter occupying an unused area on a 3.3V-only Arduino Pro board.

The maximum output current of the converter is 650 mA. It can be loaded up to 700 mA, but the inductor becomes warm. The output ripple is around 25 mV at 500 mA. If lower ripple is desired, a 3.3 µH inductor can be used. The output capacitor can also be increased; however, the benefits are marginal. The measured efficiency of this circuit is approximately 90%.

Project files—including Eagle schematic and layout files, as well as Gerbers—are available in the Resources section. The design rules are fairly relaxed, and the board is routed almost entirely on one side (with the other side serving as a ground plane), so making one at home should not be a problem.