This board provides a complete power management solution for LiPoly battery technologies to enable the development of low-power projects that utilize single-cell LiPoly batteries.
It is a significant improvement over existing solutions. The design of this board enable it to perform across a wide variety of load conditions, and has been fully tested in a labratory setting such that its behavior is well understood.
All of the design files are open-source and documented to support quick drop-in design scenarios.
Currently existing solutions, such as Sparkfun's Power Cell, are poorly implemented, cannot handle advertised load, and have completely unacceptable quintessential current consumption. These designs have been rushed to market and are not suitable for anything more advanced than the most rudimentary proof of concept demonstrations.
Significant design errors were found in the Sparkfun Power Cell, and other designs. Additionally no existing design integrates current sensing capabilities, voltage measurement, wide-range input voltages suitable for standard poorly regulated power adapters, or simultaneous load-sharing between charging and system supplies, allowing for simultaneous charging and powering of the host device.
All of these challenges needed to be solved to create a solution that would be suitable for actual usage in a commercial product, or even moderately complex hobbyest projects that require long battery life, and reliable operation.
The design space currently includes products produced by Sparkfun and other small scale device manufacturers. These devices are based around less sophisticated charge controller chips such as the MAX1555. While some of the boost-up solutions use the TPS61200 as we have used, the implementation was lacking. The biggest limitations are listed below.
While designing this circuit, a number of challenges were encountered. Creating a proper design for the TPS61200 proved to be challenging, as non of the reference designs performed adequitly.
The big design goal of the TPS61200 part was to handle a high constant current, and to provide capacity for large transient current spikes. While the part's datasheet specified it should be perfectly capable of handling both these goals, in practice it proved extremely difficult.