Monolithic Power Systems Inc. MP7747DQ-LF-Z

Overview

MP7747DQ-LF-Z from Monolithic Power Systems is a mono 20W Class D audio amplifier with integrated 250mΩ N-channel MOSFETs, programmable undervoltage protection (UVP), and single-ended output architecture delivering 20W into 4Ω at 24V. It operates from 9.5V–36V, achieves 91% efficiency at full load, and features built-in startup/shutdown pop elimination for speaker protection in consumer audio systems.

For engineers reviewing the MP7747DQ-LF-Z datasheet, MP7747DQ-LF-Z pinout, MP7747DQ-LF-Z application, or MP7747DQ-LF-Z equivalent, key selection criteria include its 10-pin QFN3×3 package, THD+N of 0.02% at 1W/8Ω, thermal shutdown at 150°C, and AAM™ modulation enabling high-fidelity audio with low EMI in space-constrained designs.

Technical Context

The MP7747DQ-LF-Z implements Monolithic Power Systems' proprietary Analog Adaptive Modulation™ (AAM) topology, a variable-frequency switching scheme that maintains linearity and fast transient response without external clock synchronization. Its differential input stage accepts signals referenced to VDD/2, with internal biasing on PIN and feedback closure at NIN.

It integrates dual 250mΩ power MOSFETs in a half-bridge configuration driving a single-ended LC filter, where BS–SW bootstrap operation enables full enhancement of the high-side FET. Protection includes cycle-by-cycle current limiting (4.5A), thermal shutdown with 30°C hysteresis, and programmable UVP via external resistor divider on the UVP pin.

Key Specifications

Pinout & Package

The MP7747DQ-LF-Z is housed in a thermally enhanced 10-pin QFN3×3 mm package with exposed thermal pad, optimized for PCB heat dissipation in high-power density audio applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar mono Class D audio amplifier applications.

Compared with TAS5707PAP and TPA3110D2PWPR, MP7747DQ-LF-Z uniquely combines analog-input simplicity, 9.5–36V operation, programmable UVP, and AAM™-enabled low-THD performance in a 3×3mm footprint-making it optimal for analog-source, space-constrained, and wide-input consumer audio.

Availability

MP7747DQ-LF-Z is available at Aetrix Electronics and suitable for portable docking stations, flat panel monitors, home stereo systems, and surround sound DVD systems requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP7747DQ-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 mixed-signal ICs for power management and audio applications, headquartered in Kirkland, WA.

The MP7747 belongs to MPS's Class D Audio Amplifier product line, engineered for high-efficiency, low-EMI, and high-fidelity audio delivery in space-constrained consumer electronics with minimal external components.

FAQ

What is the minimum recommended LC filter cutoff frequency for MP7747DQ-LF-Z?

The LC filter characteristic frequency should be set between 30kHz and 50kHz to preserve full 20kHz audio bandwidth while suppressing switching noise. For a 4Ω load, use Q ≈ 0.7–1.0; typical values are 10µH inductor with 100nF film capacitor. Layout must minimize SW node loop area to prevent EMI.

How does the Timer pin control pop elimination?

The Timer pin connects to an external capacitor (e.g., 2.2µF) that sets the slew rate of internal startup current charging COUT. Larger capacitance slows the ramp, reducing turn-on pop amplitude; 2.2µF yields ~20mA/350ms. At shutdown, EN low forces SW to high-impedance, eliminating turn-off pop.

Can MP7747DQ-LF-Z drive an 8Ω speaker at full rated power?

No-it delivers 10.6W into 8Ω at 10% THD+N (VDD=24V), not 20W. The 20W rating is specified for 4Ω. Driving 8Ω at higher voltages risks exceeding absolute maximum ratings; design must respect 36V VDD limit and thermal limits per θJA=50°C/W.

What is the role of the PIN and NIN pins in the feedback network?

PIN is internally biased at VDD/2 and serves as the positive input reference for the differential modulator. NIN is the negative input where feedback is closed via RFB; together they form a virtual ground input stage. Input signal couples through CIN to NIN, while PIN remains fixed at mid-rail for common-mode stability.

Is the exposed thermal pad electrically connected to any internal node?

Yes-the exposed pad is internally connected to PGND and must be soldered to a dedicated PCB thermal plane tied to PGND. This connection is essential for achieving θJC = 12°C/W and preventing thermal shutdown under 20W continuous output.

Does MP7747DQ-LF-Z support parallel operation for higher power?

No-MP7747DQ-LF-Z is not designed for parallel operation. Its variable-frequency AAM™ modulation causes unsynchronized switching between units, leading to beat frequencies and increased EMI. For >20W, use a higher-power single-channel device like MP7749 or multi-channel discrete solutions.

What is the purpose of the BS-to-SW bootstrap capacitor?

The bootstrap capacitor (CBS) charges from VDD when SW is low, then supplies gate drive voltage >VDD to the high-side MOSFET during SW high phase. This ensures full enhancement of the 250mΩ high-side FET, minimizing conduction loss and maintaining >91% efficiency at full load.