Microchip Technology MCP73861T-I/SLG

Overview

MCP73861T-I/SLG from Microchip Technology is a fully integrated linear lithium-ion battery charge management controller for single-cell Li-ion/Li-polymer packs. It delivers ±0.5% voltage regulation at 4.1V or 4.2V, supports up to 1.2A programmable fast-charge current, integrates reverse-blocking protection and thermal regulation, and operates across –40°C to +85°C - enabling compact, reliable charging in portable medical monitors and handheld test equipment.

For engineers reviewing the MCP73861T-I/SLG datasheet, MCP73861T-I/SLG pinout, MCP73861T-I/SLG application, or MCP73861T-I/SLG equivalent, key selection criteria include its 4.1V/4.2V dual-voltage option via VSET pin, integrated PROG-based current programming, thermistor-based temperature monitoring with THREF/THERM pins, and QFN-16 package thermal performance (θJA = 37°C/W).

Technical Context

The MCP73861T-I/SLG implements a three-stage linear charging algorithm: preconditioning (trickle-charge at ~10% of IREG), constant-current fast charge (programmable 100–1200 mA), and constant-voltage regulation (4.1V/4.2V ±0.5%). It uses an internal P-channel MOSFET pass transistor with reverse-blocking protection and automatic power-down below UVLO (4.20–4.55V stop/start thresholds).

Thermal regulation dynamically scales charge current above ~90°C die temperature, while independent safety timers govern preconditioning (45–75 min), fast-charge (1.1–1.9 hr), and elapsed-time termination (2.2–3.8 hr). Cell temperature is monitored via ratio-metric comparison of THERM voltage against THREF/2 and THREF/4 thresholds, with THREF outputting 2.55V ±0.075V at 25°C.

Key Specifications

Pinout & Package

Package: 16-pin, 4 mm × 4 mm QFN (exposed pad), RoHS-compliant, moisture sensitivity level 3.

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 and BQ24075RGTR, the MCP73861T-I/SLG uniquely combines dual-voltage selection, integrated thermistor bias/reference, and 1.2A capability in a thermally optimized QFN - making it optimal for industrial-grade single-cell chargers demanding configurability and robustness.

Availability

MCP73861T-I/SLG is available at Aetrix Electronics and suitable for portable medical monitors, handheld test equipment, and industrial handheld scanners requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MCP73861T-I/SLG 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 is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and battery management ICs, with broad industrial and automotive qualification coverage.

The MCP7386X product line was designed specifically for space-constrained, cost-sensitive single- and dual-cell Li-ion/Li-polymer charging applications - emphasizing integration, thermal resilience, and autonomous operation with minimal external components.

FAQ

What is the function of the VSET pin on the MCP73861T-I/SLG?

The VSET pin on the MCP73861T-I/SLG selects the regulated battery voltage: tying VSET to VSS configures 4.1V output for coke-anode cells, while tying it to VDD selects 4.2V for graphite-anode cells. This dual-voltage capability allows one MCP73861T-I/SLG design to support multiple battery chemistries without hardware change - a key differentiator versus fixed-output alternatives like the MCP73831T-2ACI/OT.

How does the MCP73861T-I/SLG implement temperature monitoring?

The MCP73861T-I/SLG uses a ratio-metric thermistor interface: THREF provides a stable 2.55V reference to bias an external NTC or PTC thermistor, and THERM reads the resulting divider voltage. Internal comparators evaluate THERM against THREF/2 (upper threshold) and THREF/4 (lower threshold), enabling accurate, VDD-independent temperature qualification - critical for meeting UL/IEC thermal safety requirements in the final MCP73861T-I/SLG application.

Can the MCP73861T-I/SLG be used with dual-cell Li-ion batteries?

No - the MCP73861T-I/SLG is strictly for single-cell Li-ion/Li-polymer batteries (4.1V/4.2V output). Dual-cell applications require the pin-compatible MCP73862 variant, which supports 8.2V/8.4V regulation and higher input voltage (8.7–12V). Using MCP73861T-I/SLG on a two-series cell pack would result in severe undercharging and failure to reach full capacity - always verify the exact part number matches the battery configuration.

What is the maximum continuous charge current supported by the MCP73861T-I/SLG?

The MCP73861T-I/SLG supports up to 1.2A continuous fast-charge current when the PROG pin is connected directly to VSS. This value is confirmed in the DC Characteristics table (IREG = 1020–1380 mA, typical 1200 mA) and is thermally sustainable in the QFN-16 package (θJA = 37°C/W) with adequate PCB copper pour - exceeding the 500 mA limit of smaller-footprint alternatives like the MCP73831T-2ACI/OT.

Does the MCP73861T-I/SLG require external MOSFETs for battery charging?

No - the MCP73861T-I/SLG integrates a P-channel MOSFET pass transistor, eliminating the need for external switching elements. VBAT1 and VBAT2 are the drain terminals of this internal MOSFET, and the device handles all current regulation, voltage control, and reverse-blocking protection autonomously. This integration reduces bill-of-materials cost and PCB area - a core design advantage of the MCP73861T-I/SLG versus discrete charger solutions.