Monolithic Power Systems Inc. MP6551GQB-P

Overview

MP6551GQB-P from Monolithic Power Systems is a fully integrated H-bridge motor driver IC designed for brushed DC motor control in space-constrained, battery-powered systems. It operates from 2.5V to 14V input, delivers ±5A peak output current, features 15mΩ/12mΩ HS/LS MOSFET on-resistance, integrated current sensing (CM1/CM2), and full protection including OCP, UVLO, and thermal shutdown - used in mini drones and RC toys requiring bidirectional motor control.

For engineers reviewing the MP6551GQB-P datasheet, MP6551GQB-P pinout, MP6551GQB-P application, or MP6551GQB-P equivalent, key selection criteria include its QFN-14 (2.5mm×3mm) package thermal performance, independent half-bridge enable/control logic (EN1/IN1, EN2/IN2), slew-rate programmability via SR pin, open-drain nFAULT reporting, and 1:10,000 current-sense ratio for precision motor current monitoring.

Technical Context

The MP6551GQB-P integrates four N-channel power MOSFETs with gate drivers, charge pump, and protection circuitry in a single monolithic IC. Its dual half-bridge architecture supports either one bidirectional brushed DC motor or two independent unidirectional motors, with independent INx/ENx control enabling flexible PWM and direction sequencing.

It implements analog current sensing per low-side FET with 10,000:1 scaling, open-drain fault reporting tied to over-current (10–14A sink / 8.5–11.5A source) and over-temperature (>150°C) events, and configurable slew rate via external resistor on SR pin - directly impacting EMI and switching loss trade-offs in compact motor drive layouts.

Key Specifications

Pinout & Package

MP6551GQB-P is housed in a thermally enhanced QFN-14 package (2.5mm × 3mm, 0.5mm pitch) with exposed thermal pad. The package supports high-current routing and efficient heat dissipation via PCB copper planes connected to OUT1, OUT2, VIN, and GND pins.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar H-bridge motor driver applications.

Compared with TB6612FNG and VNH7040AS, MP6551GQB-P uniquely balances high-current density (5A in 2.5×3mm), integrated current sensing, and programmable slew rate - making it optimal for compact, battery-powered systems requiring both efficiency and diagnostic capability.

Availability

MP6551GQB-P is available at Aetrix Electronics and suitable for mini drones, battery-powered toys, portable medical pumps, and smart home actuators requiring stable component supply, consistent thermal performance, and long-term production continuity.

Supply support for MP6551GQB-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, founded in 1997 and headquartered in Kirkland, Washington.

The MP6551 belongs to MPS's motor driver product line, engineered specifically for compact, battery-operated motion control applications demanding high integration, thermal efficiency, and embedded diagnostics - not general-purpose power switching.

FAQ

What is the maximum continuous output current supported by MP6551GQB-P?

The MP6551GQB-P supports up to 5A peak output current across its full 2.5V–14V input range. Continuous current depends on PCB thermal design: with 2oz copper, 4 thermal vias under the exposed pad, and 1in² copper pour, it sustains ~3.5A continuously at TA = 70°C per the θJA = 65°C/W rating.

How does the SR pin affect motor drive performance?

The SR pin sets output slew rate via an external resistor to GND: 0Ω yields ~100ns edges; 3MΩ yields ~3µs edges. Slower slew reduces EMI and voltage overshoot on long motor traces but increases switching losses - optimal value balances EMC compliance and efficiency for each mechanical layout.

Can MP6551GQB-P drive a single motor in both directions using only two control signals?

No - bidirectional control requires four logic signals: IN1/EN1 for OUT1 and IN2/EN2 for OUT2. However, the device supports full H-bridge operation (forward/reverse/brake/coast) when both half-bridges are enabled and driven with complementary logic states per Table 1 in the datasheet.

What is the function of the CM1 and CM2 pins, and how are they terminated?

CM1 and CM2 are current-source outputs proportional to their respective low-side FET currents (120µA per 1A). They are typically terminated with a resistor divider between VCC and GND to generate VREF, then connected to an ADC input - producing a ratiometric voltage where zero current equals mid-scale code.

Does MP6551GQB-P require an external charge pump capacitor?

No - the MP6551GQB-P integrates an internal charge pump for high-side gate drive. Unlike discrete gate driver solutions, it needs no external flying capacitor, simplifying layout and reducing BOM count while maintaining full 100% duty-cycle capability on both high-side switches.

How does the nFAULT pin behave during over-temperature events?

During over-temperature (die >150°C), nFAULT is actively pulled low as an open-drain signal. It remains low until die temperature falls below ~135°C (15°C hysteresis), at which point the internal pull-up is disabled and the external pull-up resistor returns nFAULT to high - enabling automatic recovery without MCU intervention.

Is MP6551GQB-P compatible with 3.3V logic microcontrollers?

Yes - its input logic thresholds are VIN_LOW ≤ 0.8V and VIN_HIGH ≥ 1.5V, with ±20µA input leakage. A 3.3V MCU GPIO meets these levels comfortably, and internal 500kΩ pull-downs ensure defined states during reset or firmware boot, eliminating need for external pull-down resistors.