Microchip MCP73811T-420I/OT: A Compact Single-Cell Li-Ion/Li-Polymer Charge Management Controller

The proliferation of portable electronics has intensified the demand for efficient, reliable, and compact battery charging solutions. The Microchip MCP73811T-420I/OT stands out as a highly integrated, linear charge management controller meticulously designed for single-cell Lithium-Ion or Lithium-Polymer batteries. This device encapsulates a complete charging system in an ultra-small SOT-23-5 package, making it an ideal choice for space-constrained applications such as wearable devices, Bluetooth headsets, portable medical devices, and other compact consumer electronics.

Core Functionality and Key Features

The MCP73811T-420I/OT simplifies the design process by integrating the critical elements required for safe and precise battery charging. Its operation follows a standard three-phase charging algorithm: preconditioning (trickle charge), constant current, and constant voltage. This method ensures a safe and efficient charge cycle, maximizing battery capacity and longevity.

A defining characteristic of this controller is its fixed 4.20V regulation voltage, which is precisely optimized for the most common single-cell lithium chemistry. This precision, with an accuracy of ±0.75%, is crucial for achieving full charge capacity while strictly adhering to the voltage limits that ensure battery safety and prevent overcharging.

The device is exceptionally simple to implement, requiring a minimal number of external components—typically just an input capacitor, a programming resistor, and a pass transistor. This simplicity is enabled by its internal MOSFET pass transistor and current sense circuit, which eliminates the need for external current-sensing resistors, further reducing the overall solution size and cost. The charge current is easily set by a single external resistor, providing designers with flexibility.

Furthermore, the IC incorporates several critical protection and safety features. These include thermal regulation to reduce charge current if the die temperature exceeds ~110°C, preventing damage to the controller under high power dissipation or ambient temperature conditions. It also offers reverse discharge protection, isolating the battery from the load when the input power is removed.

Summary by ICGOOODFIND:

The MCP73811T-420I/OT from Microchip is a minimalist's solution for single-cell lithium battery charging. Its unparalleled strength lies in its extreme integration and miniature form factor, delivering a robust and complete charging management system with virtually no design overhead. For applications where PCB real estate is the most valuable currency, this controller provides an unbeatable combination of reliability, safety, and simplicity.

Keywords:

1. Charge Management

2. Li-Ion/Li-Polymer

3. 4.20V Regulation

4. Thermal Regulation

5. SOT-23-5