Monolithic Power Systems Inc. MP2681BGS-Z

Overview

MP2681BGS-Z from Monolithic Power Systems is a highly integrated Li-ion/Li-polymer switch-mode battery charge controller for power tools, featuring automatic 3S/4S/5S battery cell detection via ID resistor, precision CC/CV regulation (4.158 V/cell typ.), full protection (NTC monitoring, timer fault, ID validation), and dual LED status indication. It operates from 5.0 V to 30 V input and integrates a 5 V LDO for NTC/ID/FLT biasing.

For engineers reviewing the MP2681BGS-Z datasheet, MP2681BGS-Z pinout, MP2681BGS-Z application, or MP2681BGS-Z equivalent, key selection criteria include its automatic multi-cell configuration detection, pre-charge safety mode (150 mA fixed), programmable fast/slow charge rate control via CR pin, and integrated fault signaling through CCON, FLT, LEDR, and LEDG outputs.

Technical Context

The MP2681BGS-Z implements a dual-loop CC/CV control architecture using internal op-amps with 1 MHz bandwidth, where VFB regulates voltage and IFB senses current via external shunt. Its battery identification logic compares VID against six pre-set thresholds (e.g., 0.3–0.7 V for 3S, 0.95–1.6 V for 4S) to auto-configure charge voltage (12.44 V, 16.59 V, or 20.74 V) and adjust flyback reference accordingly.

Thermal and safety management is hardware-based: NTC voltage is compared against four hysteresis-controlled thresholds (VT1–VT4) to gate charging and scale current; the TMR pin sets a programmable oscillator (15 Hz @ 0.1 µF) that enforces fixed 60-min pre-charge timeout and scalable total charge limits (2 hr fast / 8 hr slow); CCON drives an external MOSFET gate to physically disconnect the charge path on any fault.

Key Specifications

Pinout & Package

MP2681BGS-Z is housed in a 16-pin SOIC package with standard thermal pad layout and 1.27 mm pitch. The package supports surface-mount assembly and provides θ_JA = 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 CC/CV charge controller applications.

Compared with BQ24610RTWR and ISL9238HRZ-T, MP2681BGS-Z delivers superior integration for power tool applications through its on-chip LDO, automatic 3S/4S/5S detection, and unified LED status signaling - reducing layout area by 35% and eliminating 5 external passive components versus either alternative.

Availability

MP2681BGS-Z is available at Aetrix Electronics and suitable for power tool battery chargers, stand-alone fast chargers, industrial cordless equipment, and medical portable device chargers requiring stable component supply and long-term lifecycle support.

Supply support for MP2681BGS-Z 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.

The MP2681B product line targets high-power portable equipment requiring robust, integrated battery charging solutions - specifically engineered for power tools, cordless industrial gear, and professional-grade portable devices demanding reliability under variable thermal and load conditions.

FAQ

What battery chemistries and configurations does MP2681BGS-Z support?

MP2681BGS-Z supports Li-ion and Li-polymer batteries in 3S (12.44 V), 4S (16.59 V), and 5S (20.74 V) configurations. Detection is automatic via ID resistor voltage thresholds (e.g., 0.3–0.7 V for 3S). It does not support LiFePO₄ or NiMH chemistries, nor 1S/2S or 6S+ configurations.

How does the MP2681BGS-Z handle battery temperature monitoring without external ADC?

The IC uses a dedicated NTC pin (Pin 11) that reads voltage from an external NTC thermistor divider. Internal comparators evaluate this voltage against four factory-trimmed thresholds (e.g., 23–27% V_LDO at 50°C) to determine safe charging windows - no microcontroller or ADC is required.

Can the MP2681BGS-Z operate without an ID resistor in the battery pack?

Yes. If the ID pin (Pin 10) is left floating or driven to a valid VID voltage (e.g., 0.5 V for 3S), the IC defaults to 3S configuration. A missing or out-of-range ID voltage triggers sleep mode (10.8 V output) and flashes LEDR to indicate fault.

What is the function of the CCON pin during normal and fault conditions?

CCON (Pin 16) is an active-low gate driver for the external high-side MOSFET. During normal charge, it remains low to enable current flow. On any fault (NTC, timer, ID, power-line), it goes high to immediately disconnect the battery - providing hardware-level isolation independent of software or timing margins.

How is charge termination determined, and is it adjustable?

Termination occurs when charge current drops to 10% of the programmed I_CHG (IBF = 0.1 × I_CHG). This threshold is fixed by internal design and not user-adjustable; however, I_CHG itself is set externally via the sense resistor and CR pin selection (fast/slow mode).

Does MP2681BGS-Z support automatic recharging after battery voltage drop?

Yes. When battery voltage falls below 3.95 V/cell, the IC automatically restarts charging from CV mode (not pre-charge), provided no fault condition persists. Recharge is disabled if NTC is out of range or timer fault is latched.

What is the role of the LDO output (Pin 13), and what loads can it drive?

Pin 13 delivers a regulated 5.0 V ±0.2 V supply capable of sourcing up to 20 mA. It directly powers the NTC voltage divider, ID resistor network, and FLT pull-up resistor - eliminating need for external bias rails and ensuring consistent sensor reference across operating conditions.