28V input, 1-4 cell Li-Ion charger in a 28-SSOP
The MAX1737EEI+ from Analog Devices (formerly Maxim Integrated) is a standalone constant-current Li-Ion battery charger IC designed to charge 1 to 4 series cells. It accepts a supply voltage up to 28V, making it suitable for applications powered by unregulated wall adapters, automotive 12V rails, or multi-cell battery packs. The device is packaged in a 28-SSOP (0.154", 3.90mm width) for surface-mount assembly and operates over the industrial temperature range of -40°C to 85°C.
Constant-current charging with timer-based termination
This charger uses a constant-current charging algorithm, which is the standard approach for Li-Ion cells up to the voltage regulation threshold. The only programmable feature is a timer, so charge termination is based on timeout rather than current tapers or temperature monitoring. This simplifies the BOM for fixed-capacity battery packs where the charge time is well-characterized, but it means the designer must ensure the timer period matches the cell capacity and charge current to avoid under- or over-charging.