Microchip Technology MCP73843-420I/MS

Overview

MCP73843-420I/MS from Microchip Technology is a linear lithium-ion battery charge management controller for single-cell 4.2V Li-ion/Li-polymer packs. It delivers ±0.5% voltage regulation accuracy, programmable fast-charge current via external sense resistor, preconditioning for deeply depleted cells, automatic end-of-charge termination at ~7% I_REG, and open-drain STAT1 status output for LED indication. It operates from 4.5V to 12V input and supports cradle chargers and portable medical devices.

For engineers reviewing the MCP73843-420I/MS datasheet, MCP73843-420I/MS pinout, MCP73843-420I/MS application, or MCP73843-420I/MS equivalent, key selection criteria include its 4.2V fixed regulation, absence of integrated thermistor monitoring (vs. MCP73841), MSOP-8 package footprint, UVLO thresholds (4.25–4.60V start), and compatibility with external P-channel MOSFET gate drive.

Technical Context

The MCP73843-420I/MS implements a three-phase charging algorithm: qualification/preconditioning (trickle-charge at ~10% I_REG if V_BAT < 2.85V), constant-current fast charge (regulated by V_FCS = 110 mV across R_SENSE), then constant-voltage regulation at 4.2V ±0.5%. Safety timers-preconditioning (60 min), fast-charge (1.5 hr), and elapsed-time termination (3.0 hr)-are scaled by a single 0.1 µF capacitor on TIMER pin.

Unlike MCP73841/MCP73842, it omits THREF and THERM pins, removing continuous cell temperature monitoring. Its DRV output drives an external P-MOSFET in linear mode; STAT1 provides open-drain status signaling with defined states for qualification (OFF), charging (ON), completion (OFF), and faults (1 Hz flash). UVLO ensures operation only above 4.25V.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (3.0 mm × 4.9 mm, 0.65 mm pitch), RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73843-420I/MS, MCP73831T-420I/OT reduces external components but sacrifices current scalability and thermal headroom, while BQ24075RGTR offers USB integration and digital control at the cost of analog flexibility and preconditioning capability.

Availability

MCP73843-420I/MS is available at Aetrix Electronics and suitable for smartphone cradle chargers, portable medical monitors, handheld barcode scanners, digital audio recorders, and industrial handheld instruments requiring stable component supply and long-term manufacturability.

Supply support for MCP73843-420I/MS 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 devices, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.

The MCP7384X family was designed specifically for cost-sensitive, space-constrained Li-ion/Li-polymer charging applications requiring fully autonomous, analog-based CC/CV control without MCU dependency or complex configuration.

FAQ

What is the exact voltage regulation accuracy of the MCP73843-420I/MS?

The MCP73843-420I/MS provides ±0.5% maximum voltage regulation accuracy at 4.2V across the full operating temperature range of -40°C to +85°C. This specification is guaranteed per DS21823D-page 3, Table 1-1, and ensures precise termination for graphite-anode Li-ion cells to maximize cycle life and safety compliance.

Does the MCP73843-420I/MS support battery temperature monitoring?

No, the MCP73843-420I/MS does not support battery temperature monitoring. It lacks the THREF and THERM pins present on MCP73841/MCP73842. Temperature sensing is intentionally omitted to reduce cost and complexity for applications where ambient thermal control is sufficient. The MCP73843-420I/MS relies solely on voltage- and timer-based safety mechanisms.

How is the fast-charge current programmed on the MCP73843-420I/MS?

The fast-charge current is programmed using an external sense resistor (R_SENSE) between VDD and the external P-MOSFET source. The MCP73843-420I/MS regulates the voltage drop across R_SENSE to 110 mV (typical), so I_REG = 0.11 V / R_SENSE. For example, a 220 mΩ resistor sets I_REG ≈ 500 mA. This analog method requires no digital interface or calibration.

What safety timers are implemented in the MCP73843-420I/MS and how are they configured?

The MCP73843-420I/MS implements three hardware safety timers: preconditioning (60 min), fast-charge (1.5 hr), and elapsed-time termination (3.0 hr). All are scaled by a single timing capacitor (C_TIMER) connected from the TIMER pin to VSS. With C_TIMER = 0.1 µF, each timer achieves its nominal duration; values scale linearly (e.g., 0.2 µF doubles all periods).

Can the MCP73843-420I/MS be used with dual-cell Li-ion battery packs?

No, the MCP73843-420I/MS is designed exclusively for single-cell Li-ion/Li-polymer packs with 4.2V regulation. Dual-cell applications require 8.2V or 8.4V regulation and higher input voltage range (8.7–12V), which are supported only by MCP73842 or MCP73844 variants. Using MCP73843-420I/MS with a dual-cell pack would result in undercharging and failure to reach full capacity.