MCP73812T-420I/OT: A 500mA Linear Li-Ion/Li-Polymer Charge Management Controller

The MCP73812T-420I/OT is a highly integrated, single-cell, fully linear charge management controller designed for space-constrained and cost-sensitive applications. This device provides a compact and efficient solution for charging lithium-ion (Li-Ion) and lithium-polymer (Li-Polymer) batteries with a programmable charge current of up to 500mA. Housed in a tiny SOT-23-5 package, it is ideal for portable electronics like Bluetooth headsets, handheld instruments, and other low-power portable devices.

A key feature of the MCP73812T-420I/OT is its simplified design with minimal external components. The controller integrates a pass transistor and current-sense resistor, significantly reducing the bill of materials (BOM) and overall PCB footprint. The device operates from an input voltage range of 4.5V to 6.0V, making it compatible with common USB and AC adapter power sources. It employs a constant-current/constant-voltage (CC/CV) charging algorithm with thermal regulation to maximize charge efficiency without overheating. This ensures the battery is charged safely and efficiently by automatically reducing the charge current if the junction temperature exceeds approximately 110°C.

The termination scheme is precisely controlled; the charge cycle is terminated based on a minimum current threshold. An integrated charge status output pin provides a visual or logical indication of the charging process, signaling states such as charge-in-progress, charge-complete, and shutdown. For ultimate safety, the controller includes automatic safety timers and reverse discharge protection, safeguarding both the charger and the battery from potential damage.

ICGOOODFIND: The MCP73812T-420I/OT stands out for its exceptional integration, eliminating the need for an external MOSFET and current-sense resistor. Its compact form factor, robust safety features, and thermal management make it an superior choice for designers seeking a reliable, simple, and space-efficient charging solution for single-cell Li-Ion/Li-Polymer batteries.

Keywords: Linear Charger, Li-Ion Battery, Thermal Regulation, Charge Management, SOT-23-5.