Fit a complete battery system (cell, charger IC, protection, and USB-C port) into a wearable form factor where every millimeter counts.
The Solution
Designed around a 20×30mm LiPo cell with a single-chip charge controller that integrates protection (OVP, UVP, OCP) to minimize component count. USB-C connector for charging and power output, no proprietary dock. The layout packs the USB-C with its configuration resistors, charge controller, protection FETs, and cell connections into the remaining board area.
Results
The module plugs directly into the client's wearable mainboard via USB-C and reports battery discharge status and parameters to the host, so the wearable can manage its own power budget.
How the module stays small
One chip does most of the work. A charge controller with protection built in keeps the part count down, USB-C handles both charging and power output, and the host reads the battery status so the wearable can manage its own power budget.Heat is the real limit on a board this small. The charger turns the difference between the 5 V from USB-C and the cell voltage into heat, so the worst moment is the start of a charge, with a flat cell and the full current flowing. Sizing the charge current against that peak, rather than against the cell rating alone, keeps a module with no room for a heatsink cool against the skin.
Have a Similar Challenge?
Compact battery systems with integrated protection are a regular design task.
