Microchip Technology MCP73837T-FJI/UN

Overview

MCP73837T-FJI/UN from Microchip Technology is a fully integrated linear Li-Ion/Li-Polymer battery charge management controller with autonomous AC adapter or USB port source selection, ±0.5% voltage regulation accuracy, 4.20V fixed charge voltage, 100 mA to 1 A programmable AC charge current, and thermal regulation. It is used in portable medical devices and ultra-mobile consumer electronics requiring dual-source charging and battery temperature monitoring.

For engineers reviewing the MCP73837T-FJI/UN datasheet, MCP73837T-FJI/UN pinout, MCP73837T-FJI/UN application, or MCP73837T-FJI/UN equivalent, key selection criteria include its 3 mm × 3 mm DFN-10 package, integrated reverse discharge protection, dual open-drain status outputs (STAT1/STAT2), PG output for power-good indication, and thermistor-based battery temperature monitoring capability.

Technical Context

The MCP73837T-FJI/UN implements a CC/CV charge algorithm with factory-set 4.20V regulation, preconditioning for deeply depleted cells, and automatic recharge at 94% of VREG. Its autonomous power source selection prioritizes VAC over VUSB, and it uses internal sense FETs with 350 mΩ typical R_DS(ON) for charge path control.

Thermal regulation dynamically reduces charge current above 150°C junction temperature, while UVLO provides separate thresholds for USB (3.45 V start) and AC (4.15 V start) inputs with built-in hysteresis. The device supports LDO mode via THERM pin assertion and includes a 50 µA thermistor bias current source.

Key Specifications

Pinout & Package

Package: 10-Lead 3 mm × 3 mm DFN with exposed thermal pad (EP), internally connected to VSS. Requires soldering EP to PCB ground plane for optimal thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73831T-2ACI/OT, MCP73837T-FJI/UN adds AC/USB arbitration and thermal monitoring; compared with BQ24075RGTR, it offers superior input source hierarchy and dedicated power-good signaling-both critical for certified portable medical and dual-port consumer devices.

Availability

MCP73837T-FJI/UN is available at Aetrix Electronics and suitable for smartphone battery charging, portable medical monitors, Bluetooth headset docks, and ultra-mobile PDAs requiring stable component supply, full JEITA thermal compliance, and dual-source autonomy.

Supply support for MCP73837T-FJI/UN 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 microcontroller, analog, FPGA, and mixed-signal semiconductor solutions headquartered in Chandler, Arizona.

The MCP73837/8 product line was designed specifically for space-constrained portable electronics requiring autonomous dual-input Li-ion charging with integrated safety features-including thermal regulation, reverse discharge blocking, and precise voltage accuracy-without host processor dependency.

FAQ

What is the fixed charge voltage of the MCP73837T-FJI/UN?

The MCP73837T-FJI/UN has a factory-set constant-voltage regulation point of 4.20 V ±0.5%, optimized for standard single-cell Li-ion and Li-polymer batteries. This value is not user-programmable and is guaranteed across -40°C to +85°C ambient temperature.

Does the MCP73837T-FJI/UN support both AC adapter and USB charging simultaneously?

No-MCP73837T-FJI/UN implements autonomous source selection: when both VAC and VUSB are present, the AC adapter takes priority and powers the charge circuit exclusively. USB is used only when VAC is absent, ensuring predictable power-path behavior without external arbitration logic.

How is battery temperature monitored on the MCP73837T-FJI/UN?

The MCP73837T-FJI/UN monitors battery temperature using its THERM pin, which sources a precise 50 µA current into an external NTC thermistor. The resulting voltage is compared against internal thresholds (VT1 = 1.23 V, VT2 = 0.25 V) to enforce JEITA thermal charge zones, suspending charge outside safe ranges.

What is the function of the PG pin on the MCP73837T-FJI/UN?

The PG (Power-Good) pin on MCP73837T-FJI/UN is an open-drain output that pulls low when a valid input supply (VAC or VUSB) is detected above UVLO thresholds. It provides hardware-level confirmation of input readiness-distinct from STAT1/STAT2-and is used for system power sequencing or UI indication.

Can the MCP73837T-FJI/UN be used without a thermistor?

Yes-the MCP73837T-FJI/UN operates normally without a thermistor connected. In that case, THERM floats near 0 V, placing the device in the "cold" zone and allowing full-charge operation. However, JEITA thermal compliance is forfeited, and designs requiring medical or industrial safety certification must implement the thermistor network.