Monolithic Power Systems Inc. MP2681GS-P

Overview

MP2681GS-P from Monolithic Power Systems is a highly integrated Li-ion/Li-polymer switch-mode battery charge controller for power tool chargers, featuring automatic 3S–5S battery configuration detection via ID resistor, precision CC/CV regulation (4.15 V/cell ±12.5 mV), pre-charge mode (150 mA fixed), and full fault protection including NTC monitoring, timer-based safety cutoff, and open-drain FLT fault reporting. It operates from 4.5 V to 30 V input and delivers status indication via dual LED drivers.

For engineers reviewing the MP2681GS-P datasheet, MP2681GS-P pinout, MP2681GS-P application in cordless power tools or standalone fast chargers, or MP2681GS-P equivalent for multi-cell Li-ion battery management, this page provides verified functional context, validated pin-level design meanings, real-world protection thresholds, and confirmed alternative options with documented electrical and application differences.

Technical Context

The MP2681GS-P implements a dual-loop CC/CV control architecture using two 1 MHz bandwidth op-amps - one for voltage regulation (COMP pin driving opto-coupler cathode) and one for current limiting (IFB sensing across external shunt). Battery cell count (3S–5S, 1P/2P) is determined by VID voltage at the ID pin against six factory-trimmed thresholds (e.g., 3.534 V for 3S1P), triggering internal resistor-divider reconfiguration to set VBATT = 12.45 V / 16.6 V / 20.75 V.

It integrates a 5 V LDO (±2% tolerance, 20 mA max) powering NTC/ID/FLT pull-ups, a programmable oscillator on TMR pin (15 Hz with 0.1 µF), and CCON gate driver with 0.6 V hysteresis logic thresholds (VCCON_H = VBATT − 0.6 V, VCCON_L = 0.3 V) for external MOSFET control. Fault response includes immediate CCON high assertion, FLT pin pull-down, and flyback output clamping to 3.2 V/cell.

Key Specifications

Pinout & Package

MP2681GS-P is housed in a 16-pin SOIC package (SOIC16), with exposed pad not electrically connected. Thermal resistance θJA = 80 °C/W on 4-layer PCB per JESD51-7.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-ion multi-cell charge controller applications.

Compared with BQ24725A and ISL9238, MP2681GS-P delivers fully autonomous 3S–5S battery recognition, hardware-based NTC current scaling, and integrated LED status - reducing BOM cost and firmware burden in cost-sensitive, MCU-less power tool chargers.

Availability

MP2681GS-P is available at Aetrix Electronics and suitable for cordless power tool cradle designs, standalone fast chargers, and industrial portable equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP2681GS-P 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with core expertise in DC/DC conversion, battery management, and motor control solutions.

The MP2681 belongs to MPS's battery charge controller product line, engineered specifically for high-reliability, multi-cell Li-ion charging in power tools and portable industrial equipment - emphasizing autonomous configuration detection, robust fault handling, and minimal external component count.

FAQ

What battery configurations does MP2681GS-P support, and how is detection implemented?

MP2681GS-P supports six configurations: 3S1P, 3S2P, 4S1P, 4S2P, 5S1P, and 5S2P. Detection occurs via analog VID voltage at the ID pin, compared against six factory-trimmed thresholds (e.g., 3.534 V for 3S1P). No firmware or external MCU is required - the IC autonomously configures VBATT regulation, charge current scaling, and timer settings based on the measured VID.

How does the MP2681GS-P handle deeply discharged batteries?

When BATT voltage falls below 3.0 V/cell, MP2681GS-P enters fixed pre-charge mode: it disables the external MOSFET (via CCON high), regulates flyback output to 3.2 V/cell, and sources 150 mA constant current through the BATT pin. This mode lasts up to 60 min (3S1P) or 90 min (3S2P) before faulting if voltage remains below threshold.

Can the MP2681GS-P operate without a battery ID resistor?

Yes. If the battery pack lacks an ID resistor, the charge termination voltage can be manually configured by applying one of six predefined VID voltages (e.g., 0.265–0.475 V for 5S2P) directly to the ID pin. The IC interprets this as a valid configuration and sets VBATT = 20.75 V accordingly - enabling compatibility with legacy or non-standard packs.

What protections are implemented on the NTC pin, and how do they affect charging?

MP2681GS-P monitors NTC pin voltage against four thresholds (VT1–VT4) corresponding to 0°C–45°C. Charging is suspended if VNTC falls outside VT1–VT4. Within VT2–VT3 (typical operating range), full ICHG applies; between VT1–VT2, ICHG is reduced to 25% - a hardware-enforced thermal derating that requires no software intervention.

How is charge termination determined, and what happens after termination?

Charge terminates when sensed current drops to 10% of programmed ICHG (IBF threshold). Upon termination, CCON goes high to disconnect the battery, flyback output is regulated to 3.2 V/cell, and LEDG turns ON while LEDR stays OFF. If battery voltage later drops to 3.95 V/cell, auto-recharge initiates - restarting the full CC/CV cycle.

What is the function of the FLT pin, and how should it be interfaced?

FLT is an open-drain fault indicator pulled low on any asserted fault (NTC out-of-range, timer timeout, ID error, power line fault). It must be pulled up to the LDO pin (5 V) via a resistor (typically 10 kΩ). FLT assertion coincides with CCON going high and flyback output clamping - providing hardware-level fault signaling for system-level monitoring or latch circuits.

Does MP2681GS-P require external compensation components for stability?

Yes. The COMP pin drives the opto-coupler cathode in the flyback feedback loop and requires external RC compensation (e.g., 10 kΩ + 1 nF) between COMP and GND to ensure phase margin >45° across line/load/temperature. The VFB pin connects to the opto-anode and forms the voltage-sense node - compensation values depend on transformer turns ratio and opto CTR.