The first step to designing a battery charger is choosing a battery charger IC from the vast field of available solutions. To make an informed decision, a design team must first clearly define the battery parameters (chemistry, cell count, etc.) and the input parameters (solar, USB, etc.). The team must then search for chargers that fit the input and output parameters, comparing numerous data sheets to settle on the best solution. The selection process should allow the team to pick the best solution for the application, until of course, the design parameters change, at which point: back to the data sheets.
What if this step could be skipped altogether? What if a designer could focus on an application solution, treating the battery charger IC as a black box to be filled in with a real IC when the time comes to produce a working solution? At that time, the designer simply reaches to the shelf for a generic battery charger IC, regardless of the essential design parameters. Even if application parameters change (inputs switched out, battery type changed, etc.) the off-the-shelf battery charger IC still fits. No additional data sheet search required.
This problem can be illustrated by looking at two very different battery charger problems:
- Design team A is tasked with designing a battery charger that takes solar panel input and charges a lead-acid battery. The charger must stand alone—no microcontroller here—but should be versatile enough to support a few different solar panel models. They have one week to produce a schematic design.
- Design team B has a more involved charger problem. Their design takes a 5 V USB supply and charges a 1 cell Li-ion battery with 1.3 A to a termination voltage of 4.1 V per cell. Above 47°C, they want to decrease their charge voltage to 4 V per cell at 0.5 A, and above 72°C, they want charging to stop. The microcontroller in their system needs to know the battery’s voltage, current, temperature, and health. They also have one week to produce a schematic design.
It turns out that both design teams can use the same battery charger IC, and that this device is arguably the best choice available for both applications.