Monolithic Power Systems Inc. MP2639CGR-P

Overview

MP2639CGR-P from Monolithic Power Systems is a highly integrated switch-mode battery management IC for 2-cell Li-ion/Li-polymer applications, supporting bidirectional 5V ↔ 8.4V conversion with up to 2.5A charge current and 5.0A discharge current, integrated cell balancing, NTC-based thermal monitoring, and four-LED fuel gauge - deployed in power banks and portable power stations.

For engineers reviewing the MP2639CGR-P datasheet, MP2639CGR-P pinout, MP2639CGR-P application, or MP2639CGR-P equivalent, this page delivers verified technical context, QFN-26 package mapping, mode-selectable step-up/step-down topology, cell-level voltage sensing via MID pin, and real-world design meaning behind programmable ISET/OLIM/ILIM resistor networks.

Technical Context

The MP2639CGR-P implements a dual-role synchronous buck-boost architecture: in charge mode (MODE = low), it operates as a step-up converter using Q2 as main switch and Q1 as synchronous rectifier; in discharge mode (MODE = high), it reverses function as a step-down converter with Q1 as main switch and Q2 as synchronous rectifier. The MID pin enables per-cell voltage monitoring for balanced charging of series-connected cells.

It integrates three-phase charging control (trickle → constant-current → constant-voltage), auto-recharge at 8.00V, programmable timer backup (CTMR), and dual-protection loops: input OVP (5.75V), battery OVP (103.3% of 8.38V), thermal regulation at 120°C, and NTC-based cold/cool/warm/hot thresholds referenced to internal VREF.

Key Specifications

Pinout & Package

MP2639CGR-P is housed in a thermally enhanced QFN-26 (4mm × 4mm, 0.5mm pitch) package with exposed thermal pad connected to PGND. Pin functions are validated per MPS MP2639C Rev. 1.01 datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional 2-cell Li-ion management applications.

Compared with BQ25895RTWR and IP2326, MP2639CGR-P uniquely combines bidirectional conversion, MID-based cell balancing, and four-zone NTC monitoring in one QFN-26 package - reducing component count by ≥3 ICs while enabling certified battery safety compliance.

Availability

MP2639CGR-P is available at Aetrix Electronics and suitable for power bank development, portable power station production, and ruggedized mobile device battery systems requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for MP2639CGR-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 power management ICs, with over two decades of expertise in DC/DC converters, battery chargers, and motor drivers.

The MP2639C product line targets portable energy storage systems requiring compact, efficient, and safety-certifiable battery management - designed specifically for USB-powered 2-cell Li-ion applications where space, thermal performance, and functional integration are critical.

FAQ

What is the purpose of the MID pin, and how must it be connected?

The MID pin connects to the junction between two series-connected Li-ion cells to enable per-cell voltage monitoring. In 2-cell applications, it must be wired directly to that midpoint; if unused (e.g., in single-cell or non-balanced designs), it must be tied to AGND. Leaving MID floating violates absolute maximum ratings and risks incorrect cell balancing or fault detection.

Can MP2639CGR-P operate without an external inductor?

No. The MP2639CGR-P requires an external 2.2µH power inductor (as specified in the typical application circuit) to implement its synchronous buck-boost topology. Omitting the inductor prevents energy transfer in both charge and discharge modes, rendering the IC nonfunctional. Inductor DCR and saturation current must meet datasheet requirements to avoid thermal failure.

How does the IB pin provide battery current measurement?

The IB pin outputs a current proportional to real-time battery current (±1A = 0.4V with 53.3kΩ resistor to AGND). An external RC filter (e.g., 10kΩ + 10nF) converts this to a stable voltage for ADC reading. Polarity reverses between charge (IB sinks current) and discharge (IB sources current), allowing bidirectional monitoring without polarity-switching circuitry.

What happens during thermal regulation, and how is it different from thermal shutdown?

At 120°C, thermal regulation activates: the IC dynamically reduces charge/discharge current to hold die temperature constant, maintaining operation without interruption. Thermal shutdown occurs only if regulation fails and temperature reaches 150°C - then all switching halts until cooldown below 135°C, after which soft-start resumes. Both mechanisms are hardware-based and require no firmware intervention.

Is the MP2639CGR-P compatible with USB Power Delivery (USB-PD) sources?

The MP2639CGR-P accepts 4–5.75V input and is fully compatible with standard 5V USB-PD profiles. However, it does not negotiate PD contracts - it treats any 5V source as valid input. For variable-voltage PD inputs (e.g., 9V/12V), an external buck converter must first regulate to 5V before connecting to VL, as exceeding 5.75V triggers OVP shutdown.

How is cell balancing initiated, and what components are required?

Cell balancing activates automatically when voltage difference between cells exceeds 65mV (ΔVCELL), using internal 6Ω high-side and low-side MOSFETs to dissipate excess energy as heat. No external components are needed - balancing current is limited by internal Rds(on) and thermal headroom. Balancing only occurs during charge mode and ceases once ΔVCELL falls below 35mV hysteresis.

What is the role of the PB pin in discharge mode, and what timing thresholds apply?

In discharge mode, the PB pin serves as a momentary push-button interface: pressing <2.5s enables discharge (latched), pressing >2.5s disables it. After enabling, LEDs remain lit for 5s regardless of load. The internal pull-up ensures reliable detection without external components, and debouncing is handled in hardware - no software polling or external RC filtering is required.