Micro USB Dual Supply
The Micro USB Dual Supply module can give you some great options to add redundancy to USB-powered projects. This unit is built by the highly reputable 8086 Consultancy, so you know it’s going to be a tried, tested and dependable building block!
Designed for 5V USB supplies, there are a pair of Micro USB sockets on the input side and a stacked pair of USB A sockets on the output. Power from either of the Micro USB inputs is routed through a MOSFET acting as an ideal diode to the output USB A. The ideal diode arrangement means that power is prevented from feeding back into the Micro USB ports and it will automatically balance the draw between the two inputs, favouring the input with higher voltage first. Though it’s a simple circuit, it’s very effective, and a great way to have redundant power for, say, a Raspberry Pi running your Home Assistant/openHAB server.
Data is also passed through the system should you require it, but it isn’t mixed! The Micro USB are labelled as are the stacked USB A (labelled “top” and “bottom”) and each micro USB connects its data lines to one of the outputs. This is a feature that is often missing in boards that combine different power sources.
With one input being driven by a battery, and the other driven by an AC adapter, you can easily homebrew a simple uninterruptible power supply. You can even use whatever is being powered (like a Pi or Arduino) to monitor the system and automatically shut down if the voltage gets too low. There are a lot of projects out there that could benefit from having a reliable power backup! Make sure to check out the product page for more details.