Monolithic Power Systems Inc. MP26123DR-LF-P

Overview

MP26123DR-LF-P from Monolithic Power Systems is a monolithic 2A, 600kHz synchronous step-down switching Li-ion battery charger IC for 2- or 3-cell packs, featuring integrated 0.2Ω high-side MOSFET, ±0.75% battery voltage regulation accuracy, and dual-loop current/voltage control. It operates from 9V–24V input and delivers precise constant-current/constant-voltage charging with thermal shutdown, cycle-by-cycle overcurrent protection, and NTC-based temperature monitoring - used in portable media players and netbooks requiring compact, high-efficiency battery management.

For engineers reviewing the MP26123DR-LF-P datasheet, MP26123DR-LF-P pinout, MP26123DR-LF-P application, or MP26123DR-LF-P equivalent, key selection considerations include its 2A programmable charge current via external sense resistor, 600kHz fixed-frequency operation, 2- or 3-cell configuration flexibility via CELLS pin, and integrated safety features including timer-based charge termination and battery temperature fault detection.

Technical Context

The MP26123DR-LF-P implements peak-current-mode control with dual compensation networks (COMPI for current loop, COMPV for voltage loop), enabling fast transient response and stable regulation across charge stages. Its internal 3.3V linear regulator (VREF33) powers internal circuitry and supports external biasing up to 30mA.

It uses a dedicated NTC pin with built-in window comparator (73.5% and 29.5% of VREF33 thresholds) to monitor battery temperature via thermistor divider, halting charge outside safe range. The TMR pin controls two independent timers: 30-minute trickle-charge timeout and 3-hour total cycle limit, both set by external capacitor value.

Key Specifications

Pinout & Package

MP26123DR-LF-P is housed in a thermally enhanced 4mm × 4mm QFN-16 package with exposed thermal pad on underside for efficient heat dissipation in high-current charging applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-ion switching charger applications.

Compared with BQ24133 and LTC4100, MP26123DR-LF-P provides optimal balance of integration (integrated 0.2Ω MOSFET), precision (±0.75% VBATT), and simplicity (no I²C bus or external FET drivers), making it ideal for cost-sensitive, space-constrained embedded chargers where analog autonomy is preferred.

Availability

MP26123DR-LF-P is available at Aetrix Electronics and suitable for portable media players, netbooks, and distributed power systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP26123DR-LF-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.

The MP26123 belongs to MPS's battery charger IC product line, designed specifically for compact, high-efficiency switching chargers in portable electronics - emphasizing integration, safety, and ease of implementation without microcontroller dependency.

FAQ

What is the maximum supported battery configuration for MP26123DR-LF-P?

The MP26123DR-LF-P supports exactly two configurations: 2-cell (8.4V float) when the CELLS pin is grounded, or 3-cell (12.6V float) when CELLS is left floating or tied to VREF33. It does not support 1-cell or 4-cell operation, and the float voltage is factory-trimmed to ±0.75% accuracy for each mode.

How is charge current programmed, and what is the tolerance?

Charge current is set by an external sense resistor (RS1) between CSP and BATT pins using the formula I_CHG = 200mV / R_S1. With a 100mΩ resistor, nominal current is 2.0A. The current-sense amplifier has ±1% gain error and ±0.5mV offset, resulting in ±2.5% total current accuracy over temperature and line conditions.

Does MP26123DR-LF-P support power-path management, and how is it implemented?

Yes - power-path is enabled using the ACOK open-drain output to control an external MOSFET between VIN and system rail. When ACOK is LOW (valid input), the MOSFET turns on, allowing adapter power to run the system while charging the battery. This eliminates the need for a blocking diode and reduces voltage drop by >0.4V versus diode-based solutions.

What happens when the battery voltage falls after full charge?

When VBATT drops below 4.0V per cell (e.g., due to self-discharge), the MP26123DR-LF-P automatically reinitiates charging with soft-start, resetting the TMR timer. This recharge threshold has 100mV hysteresis to prevent oscillation, and no external wake-up signal is required - enabling true maintenance charging.

Can VREF33 power external circuitry, and what are its limits?

Yes - VREF33 provides a regulated 3.3V output capable of sourcing up to 30mA. It powers internal blocks and can bias external components like thermistor dividers or level-shifters. Load regulation is ±30mV from 0–10mA, and a 1µF ceramic capacitor to GND is mandatory for stability.

What thermal protection mechanisms are built into MP26123DR-LF-P?

The device includes cycle-by-cycle current limiting, thermal shutdown at 150°C (with 20°C hysteresis), and automatic recovery upon cooling. The exposed thermal pad in the QFN-16 package must be soldered to a minimum 100mm² copper pour for effective heat transfer - junction-to-ambient θ_JA is 46°C/W on a 4-layer board.

Is there a minimum input-to-battery voltage differential required?

Yes - the MP26123DR-LF-P requires VIN ≥ VBATT + 180mV to maintain regulation and enable charging. Below this headroom, ACOK goes HIGH and charging suspends. This reverse-blocking feature prevents battery discharge back into the input source when adapter is disconnected or under-voltage.