Microchip Technology MCP73861-I/ML

Overview

MCP73861-I/ML from Microchip Technology is a fully integrated linear lithium-ion/lithium-polymer battery charge management controller for single-cell applications. It features 4.1V/4.2V selectable voltage regulation (±0.5% accuracy), programmable fast-charge current up to 1.2A, integrated pass transistor and current sense, reverse-blocking protection, and thermal regulation. It is used in space-constrained portable devices such as cellular telephones and digital cameras.

For engineers reviewing the MCP73861-I/ML datasheet, MCP73861-I/ML pinout, MCP73861-I/ML application, or MCP73861-I/ML equivalent, this device delivers precise constant-voltage/constant-current control with automatic preconditioning, safety timers, temperature monitoring, and dual status outputs for LED-driven charge/fault indication - all in a thermally enhanced 16-pin 4×4 QFN package.

Technical Context

The MCP73861-I/ML implements a three-phase linear charging algorithm: preconditioning (trickle-charge at ~10% of I_REG for deeply depleted cells), constant-current fast charge (programmable via PROG pin resistor), and constant-voltage regulation (set by VSET logic level). It integrates UVLO, thermal shutdown (155°C), and die-temperature-based current scaling to prevent overheating.

Its analog architecture includes a precision 1.2V internal reference, bias generator for external NTC/PTC thermistors (THREF = 2.55V typ.), dual open-drain status outputs (STAT1 flashing on completion, STAT2 active-low fault indicator), and internal P-channel MOSFET pass element with reverse-blocking capability. All safety timers (fast charge, precondition, termination) scale linearly with external capacitor value on TIMER pin.

Key Specifications

Pinout & Package

Package: 16-pin, 4 mm × 4 mm QFN with exposed thermal pad (EP) internally connected to VSS. Requires soldering EP to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar linear Li-ion charge management applications.

Compared with MCP73831T-2ACI/OT, the MCP73861-I/ML offers higher current, dual status outputs, and full temperature monitoring; compared with BQ24075RGTR, it requires no firmware but lacks digital control - making it ideal for cost-sensitive, autonomous single-cell chargers where analog simplicity and thermal safety are prioritized.

Availability

MCP73861-I/ML is available at Aetrix Electronics and suitable for cellular telephones, digital cameras, and hand-held instruments requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing for production builds.

Supply support for MCP73861-I/ML includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a leading provider of microcontrollers, analog components, and battery management ICs, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

The MCP7386X product line was designed specifically for cost-sensitive, space-constrained portable electronics requiring fully autonomous, high-accuracy linear charging of single- or dual-cell Li-ion/Li-Po batteries without host processor dependency.

FAQ

What is the function of the VSET pin on the MCP73861-I/ML?

The VSET pin on the MCP73861-I/ML selects the regulated battery voltage: tying VSET to VSS configures 4.1V regulation, while tying it to VDD selects 4.2V. This allows compatibility with different Li-ion anode chemistries (e.g., coke vs. graphite) and ensures optimal cell longevity and capacity. The MCP73861-I/ML does not support 8.2V/8.4V options - those are exclusive to the MCP73862/4 variants.

How does the MCP73861-I/ML handle thermal regulation during charging?

The MCP73861-I/ML monitors its own die temperature and reduces charge current when exceeding ~100°C to prevent thermal runaway. Unlike simple shutdown, it dynamically scales current while simultaneously slowing down safety timers to avoid premature charge termination. Thermal shutdown activates only above 155°C with 10°C hysteresis. This behavior is intrinsic to the MCP73861-I/ML analog control loop and requires no external circuitry.

Can the MCP73861-I/ML be used for dual-cell (8.4V) battery charging?

No, the MCP73861-I/ML is strictly a single-cell Li-ion/Li-Po charger supporting only 4.1V or 4.2V regulation. Dual-cell applications require the MCP73862-I/ML or MCP73864-I/ML, which provide 8.2V/8.4V regulation and operate from 8.7V–12V input. Pin compatibility does not imply functional equivalence - using MCP73861-I/ML on an 8.4V pack would result in undercharging and permanent capacity loss.

What is the purpose of the THREF and THERM pins on the MCP73861-I/ML?

THREF provides a stable 2.55V reference to bias an external NTC or PTC thermistor; THERM reads the resulting voltage divider output and compares it against thresholds at THREF/2 and THREF/4. This enables continuous, analog-based cell temperature monitoring across the full -40°C to +85°C operating range. The MCP73861-I/ML uses this data to suspend charging outside safe thermal limits - a mandatory feature for UL/IEC certification in portable products.

How does the STAT1 output behave on the MCP73861-I/ML versus the MCP73863-I/ML?

On the MCP73861-I/ML, STAT1 flashes (toggles) upon successful charge completion, providing visual confirmation without requiring a microcontroller. In contrast, the MCP73863-I/ML drives STAT1 low continuously after completion. This distinction is hardwired in silicon - the MCP73861-I/ML's flash behavior is fixed and cannot be reconfigured. Both variants use STAT2 identically as an active-low fault indicator.