This UPS is designed for high current projects, including
Raspberry Pi, BeagleBone, Arduino, IoT, wireless embedded applications, and
similar computing devices.
You can power directly from the input. When the input source is removed,
power is delivered from the Lithium-Ion battery. An advanced
charging algorithm prolongs battery life.
I2C is available for checking battery capacity and voltage. It can also be
used for adjusting settings such as max charge rate and input current limit.
The microUSB input can negotiate from 100mA to 3.25A with USB MaxCharge and High
Voltage Adapters.
This UPS is based on the Texas Instruments BQ25895
power management IC and the Microchip MIC2876
boost IC.
Specs
- 5.1VDC Output
- 3.5A Max continuous output
- 0mA - 5000mA max charge rate (default 2000mA)
- 3.9V - 14V input
- 90%+ Efficiency when running from Input Source
- 85%+ Efficiency when running from battery
- 50μA sleep current
Status LEDs
- Power In - Input power source connected
- Charging - Battery is charging
- Charge Complete - Battery is fully charged
- Output - Output on/off
This project is Open Source and Open Hardware under the CC
BY-SA license.
FAQ
Is a battery required?
No. This power supply will work without a battery.
How much current can the USB A output?
Up to 3.5A continuous. There is no negotiation for this output current.
Any device is capable of drawing up 3.5A, so use with caution.
Will the battery charge when the power supply is off?
Yes. The power switch will disable the output but still allow for
charging. Disabling charging can be done via I2C.
Can I connect two input sources?
No! Do not connect a micro USB input and the barrel jack input at
the same time.
Can I connect two or more devices to the output?
Yes. You can connect as many devices to the output as you'd like, provided
they do not exceed the maximum output current of 3A.
Can I connect two or more batteries in parallel?
Yes, but we do not recommend it. It can be dangerous to connect multiple
batteries in parallel.
What are the power supply requirements?
We recommend using a 12VDC 2A power supply. Ideally, this can provide 5.1V
3A output and charge the battery at a max of 2A.
You can connect any power source between 3.9V and 14VDC.
The minimum amperage of your power source depends on the max charge current of
the battery and the max current of your project. If your project draws
too much current and the voltage at the input droops more than 600mV, the UPS
will automatically reduce the charge rate of the battery. If your project
draws even more current, the battery will deliver supplemental power.
