Monolithic Power Systems Inc. MP2618EV-LF-Z

Overview

MP2618EV-LF-Z from Monolithic Power Systems is a 2–3 cell Li-ion switching battery charger IC with integrated 0.28Ω power MOSFET, 2A programmable charge current, 600kHz fixed-frequency current-mode control, and system power path management. It regulates charge voltage (±0.75% accuracy) and current via dual-loop CC/CV control, supports preconditioning of deeply depleted batteries, and delivers up to 90% efficiency in netbook and distributed power systems.

For engineers reviewing the MP2618EV-LF-Z datasheet, MP2618EV-LF-Z pinout, MP2618EV-LF-Z application, or MP2618EV-LF-Z equivalent, this device is selected for high-accuracy charging with real-time current sharing between battery and system load, thermal/NTC fault protection, and programmable timer-based charge termination - critical for portable industrial and embedded battery-powered designs.

Technical Context

The MP2618EV-LF-Z implements peak current-mode control with 600kHz oscillator and slope compensation for stable loop response. Its dual feedback architecture uses COMPI for constant-current regulation and COMPV for constant-voltage regulation, enabling precise transition between CC and CV phases.

Power path management operates by sensing system current via OUT1 and RG1/RG2, dynamically reducing charge current as system load increases - maintaining priority for VSYS while limiting total input current. Battery temperature monitoring uses an internal NTC window comparator referenced to VREF33 (3.3V) with configurable thresholds at 73% and 30% of that reference.

Key Specifications

Pinout & Package

MP2618EV-LF-Z is housed in a thermally enhanced 4mm × 5mm QFN-28 package with exposed pad (Pin 11/21) for improved heat dissipation. The package supports reflow soldering and meets RoHS requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ24725ARHBT and ISL9237HRZ-T, MP2618EV-LF-Z uniquely combines 2–3 cell configurability, autonomous power path current sharing, and integrated 0.28Ω MOSFET - reducing BOM count and eliminating firmware dependency for basic charging functions.

Availability

MP2618EV-LF-Z is available at Aetrix Electronics and suitable for netbook PC power management, distributed power system chargers, and medical portable monitors requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for MP2618EV-LF-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 expertise in DC/DC conversion, battery management, and motor control solutions.

The MP2618 product line targets portable and industrial battery-powered systems requiring high-accuracy, thermally robust, and feature-rich Li-ion charging - emphasizing autonomous operation, safety compliance, and minimal external component count.

FAQ

What is the function of the CELLS pin, and how does it affect battery voltage regulation?

The CELLS pin configures the MP2618EV-LF-Z for either 2-cell (grounded) or 3-cell (floating) operation. When grounded, the IC regulates battery voltage to 8.4V (±0.75%); when floating, it regulates to 12.6V. This hardware-selectable mode eliminates software configuration and ensures correct CV termination without external logic or firmware intervention.

How does power path management allocate current between battery charging and system load?

Power path management continuously monitors system current via the OUT1 pin and RG1/RG2 resistors. As system load increases, the IC reduces charge current proportionally - maintaining total input current within adapter limits. If charge current drops to zero, the system draws full power from VIN, and the battery remains idle until load decreases.

Can the MP2618EV-LF-Z charge a fully depleted battery below 2.5V/cell?

Yes - the MP2618EV-LF-Z initiates trickle charging at 10% of the programmed CC current (e.g., 200mA for 2A setting) until the battery reaches 3V/cell. This preconditioning stage safely recovers deeply discharged cells and prevents lithium plating, with a 30-minute timeout to prevent indefinite trickle operation on shorted cells.

What thermal protection mechanisms are implemented beyond junction shutdown?

In addition to 150°C junction thermal shutdown, the MP2618EV-LF-Z includes battery temperature monitoring via the NTC pin. Using an external thermistor and internal 73%/30% VREF33 comparators, it halts charging if battery temperature falls outside the configured window (e.g., 0°C–50°C), resuming only after temperature returns to safe range - providing dual-layer thermal safety.

Is the VREF33 output capable of powering external circuitry, and what are its limitations?

Yes - VREF33 delivers a regulated 3.3V output with up to 50mA sink/source capability. It is intended to power external NTC bias networks, level-shifters, or low-power logic. A 1µF ceramic bypass capacitor to GND is mandatory for stability. Load regulation is ±30mV from 0–10mA, making it suitable for precision analog references but not high-current digital loads.

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

Charge terminates when battery current falls below 5–15% of the programmed CC current (IBF threshold), confirmed after a 1-minute delay. CHGOK goes high (open-drain), disabling charging. If battery voltage later drops to 4.0V/cell (recharge threshold), the IC automatically restarts the charge cycle - supporting maintenance charging without host controller involvement.

What is the role of the TMR pin, and how is total charge time calculated?

The TMR pin sets both trickle-mode timeout (30 minutes) and total charge timeout (3 hours) using a single external capacitor. With CTMR = 0.1µF, the internal 0.1µA current source yields exact timing: T_TRICKLE = 0.1µF × 30min and T_TOTAL = 0.1µF × 3hrs. Connecting TMR to GND disables the timer, allowing indefinite CV charging - useful for lab validation.