Monolithic Power Systems Inc. MP2661GC-0000-P

Overview

MP2661GC-0000-P from Monolithic Power Systems is a fully integrated, I²C-controlled single-cell Li-ion/Li-polymer battery charger with autonomous power path management. It delivers up to 455mA charge current, regulates system output at 4.65V ±0.5%, and features configurable input current limit (85–455mA), battery voltage regulation (3.6–4.545V), and thermal regulation at 120°C. It is designed for space-constrained portable devices requiring simultaneous system power and battery charging from USB or AC adapter sources.

For engineers reviewing the MP2661GC-0000-P datasheet, MP2661GC-0000-P pinout, MP2661GC-0000-P application, or MP2661GC-0000-P equivalent, key selection criteria include its WLCSP-9 package footprint, I²C-programmable charge parameters (VBATT_REG, ICHG, VIN_MIN), power path behavior under DPM conditions, and integrated NTC-based temperature monitoring with cold/hot window configuration.

Technical Context

The MP2661 implements a dual-FET power path architecture: a 300mΩ LDO FET between IN and SYS enables regulated system supply independent of battery state, while a 100mΩ battery FET between BATT and SYS manages supplemental discharge and charging current routing. Its I²C interface controls 8-bit register banks governing charge profiles, safety timers, UVLO thresholds, and thermal limits.

Charge control follows a three-phase sequence-pre-charge (6–27mA), constant-current fast charge (8–535mA), and constant-voltage regulation (±0.5% accuracy at 4.2V or 4.35V)-with auto-recharge triggered when VBATT drops 120–350mV below VBATT_REG. Dynamic Power Management (DPM) actively regulates IIN or VIN to prevent source overload, reducing ICHG before entering battery supplement mode.

Key Specifications

Pinout & Package

MP2661GC-0000-P is housed in a 1.55mm × 1.55mm WLCSP-9 package with bottom-side ball layout. The package supports ultra-compact PCB designs typical of wearables and smartwatches, with thermal pad exposed on underside for enhanced heat dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-cell Li-ion charger with power path applications.

Compared with BQ25618RTWR and MAX77751EWW+T, MP2661GC-0000-P offers optimal trade-offs for space-constrained wearables: smallest WLCSP-9 footprint, I²C-tunable thermal windows for NTC-based safety, and 4.65V SYS regulation that eliminates need for external LDOs in 3.3V system designs.

Availability

MP2661GC-0000-P is available at Aetrix Electronics and suitable for wearable fitness trackers, smartwatches with always-on displays, and wireless earbud charging cases requiring stable component supply, consistent WLCSP-9 packaging, and guaranteed I²C register compatibility across production lots.

Supply support for MP2661GC-0000-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-efficiency power management ICs, with design centers in the US, China, and Taiwan, and global distribution through authorized partners.

The MP2661 belongs to MPS's battery management product line, engineered specifically for ultra-compact, USB-powered portable electronics where simultaneous system operation and battery charging must coexist without compromising safety or thermal performance.

FAQ

What is the minimum input voltage required to initiate charging?

The MP2661 requires VIN ≥ 4.35V to begin normal operation; input under-voltage lockout (VIN_UVLO) is set at 3.9V (typical) with 170mV hysteresis. Below this threshold, the IN-to-SYS LDO FET remains off, and the system relies solely on battery power if VBATT > VBATT_UVLO.

How does the MP2661 handle battery over-discharge protection?

When VBATT falls below the configurable UVLO threshold (2.6–3.0V, default 2.8V), the BATT-to-SYS FET is forcibly turned off, disconnecting the battery from the system. This prevents further discharge below safe voltage levels and avoids permanent capacity loss in Li-ion cells.

Can the MP2661 operate without an NTC thermistor?

Yes - NTC functionality is optional and disabled by default. If the NTC pin is left floating or tied to GND/VDD, temperature monitoring is inactive and charging proceeds normally. However, IEC 62368-1 compliance requires NTC implementation in production designs for thermal safety certification.

What happens during input power removal while the system is active?

Upon VIN removal, the MP2661 immediately enables the BATT-to-SYS FET, transitioning to battery-supply mode. VSYS is maintained at VBATT minus RON_BATT × ISYS drop (≤150mΩ × load current), ensuring uninterrupted system operation without brownout or reset.

Is the 455mA maximum charge current achievable at all input voltages?

No - 455mA is the upper limit of the programmable ICHG range and is only sustainable when VIN ≥ 5.0V and die temperature remains below 120°C. At VIN = 4.5V or TJ > 110°C, thermal or DPM regulation reduces ICHG to maintain VSYS stability and prevent device damage.

How is the auto-recharge threshold configured?

The auto-recharge threshold is set via REG04h bit[0] and bits[6:5], selecting either 120–200mV or 260–350mV below VBATT_REG. For example, with VBATT_REG = 4.2V and bit[0] = 0, recharge initiates when VBATT drops to ~4.02V, preventing excessive self-discharge between usage cycles.

Does the MP2661 support USB BC1.2 or proprietary fast-charge protocols?

No - the MP2661 does not negotiate USB BC1.2, QC, or PD protocols. It operates as a fixed-input charger accepting 4.35–5.5V; upstream protocol handling must be implemented externally (e.g., via USB controller or dedicated charger detector IC).