Monolithic Power Systems Inc. MPQ7731DF-LF

Overview

MPQ7731DF-LF from Monolithic Power Systems is a mono, fully integrated Class D audio amplifier delivering 5W–30W into 4Ω loads with 90% efficiency at 5W, 0.1% THD+N at 1W/1kHz, 9.5V–18V supply operation, and integrated 180mΩ full-bridge MOSFETs - deployed in flat-panel displays, TVs, and multimedia computers for high-fidelity speaker drive.

For engineers reviewing the MPQ7731DF-LF datasheet, MPQ7731DF-LF pinout, MPQ7731DF-LF application, or MPQ7731DF-LF equivalent, this page delivers verified electrical specs, thermal shutdown behavior, AAM® modulation topology details, and real-world LC filter design guidance - all confirmed against MPS Rev. 2.4 documentation and TSSOP20 package implementation.

Technical Context

The MPQ7731DF-LF implements Monolithic Power Systems' proprietary Analog Adaptive Modulation (AAM®) variable-frequency topology, enabling fast transient response, >60dB PSRR at 1kHz, and stable operation on a single supply without external clocking. Its dual-channel internal architecture drives complementary full-bridge outputs (SW1/SW2) with synchronized bootstrap gate drive (BS1/BS2).

It integrates four 180mΩ power MOSFETs, analog input stage with VDD/2 biasing (PIN1/NIN1, PIN2/NIN2), dual enable inputs (EN1/EN2), thermal shutdown at 150°C with 30°C hysteresis, and short-circuit protection - eliminating discrete gate drivers, external protection diodes, and startup pop circuitry.

Key Specifications

Pinout & Package

MPQ7731DF-LF is housed in a thermally enhanced 20-pin TSSOP package with exposed paddle (JEDEC MO-153 compliant), optimized for PCB heat dissipation in audio subsystems. Pin numbering follows standard counter-clockwise orientation from pin 1 (NC) indicator notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPA3110D2PWP and MAX9718ETA+, MPQ7731DF-LF uniquely combines 30W output, 90% efficiency, integrated full-bridge MOSFETs, and AAM® modulation - making it optimal for thermally dense, high-fidelity display and TV audio subsystems.

Availability

MPQ7731DF-LF is available at Aetrix Electronics and suitable for flat-panel displays, smart TVs, and multimedia notebooks requiring stable component supply, RoHS-compliant packaging, and long-term industrial availability.

Supply support for MPQ7731DF-LF 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 over two decades of leadership in DC-DC conversion, motor control, and audio power solutions.

The MPQ7731 belongs to MPS's second-generation Class D audio amplifier product line, engineered specifically for high-efficiency, low-EMI, and space-constrained consumer display and entertainment systems.

FAQ

What is the maximum safe operating voltage for MPQ7731DF-LF?

The absolute maximum supply voltage is 26V, but the recommended operating range is 9.5V to 18V. Exceeding 18V risks permanent damage and voids guaranteed performance specs - including 30W output and 0.1% THD+N. Operation above 18V also degrades AAM® modulation stability and increases thermal stress beyond the 150°C shutdown threshold.

Does MPQ7731DF-LF require external bootstrap capacitors?

Yes - two 1μF ceramic capacitors must be placed between BS1–SW1 and BS2–SW2. These provide gate drive charge for the internal high-side MOSFETs during each switching cycle. Omitting them causes asymmetric output drive, increased THD+N, and potential latch-up due to insufficient high-side VGS.

How does the AAM® modulation improve audio performance versus fixed-frequency Class D?

AAM® dynamically adjusts switching frequency based on input signal and load conditions, improving PSRR by >10dB at 1kHz and reducing spectral energy at harmonics that interfere with RF bands. It also lowers idle-state EMI and eliminates beat frequencies with external clocks - critical for HDMI-integrated displays.

Can MPQ7731DF-LF drive an 8Ω speaker at full rated power?

No - its 30W rating is specified into 4Ω. Into 8Ω, maximum output is 17W at 10% THD+N (per Operating Specifications table). Attempting 30W into 8Ω exceeds safe SOA limits and triggers thermal shutdown; design must use appropriate gain scaling and LC filter Q tuning for 8Ω loads.

What is the purpose of separating AGND1/AGND2 from PGND1/PGND2?

AGND1/AGND2 form a quiet analog reference plane for differential inputs and bias networks, while PGND1/PGND2 carry high-di/dt switching currents. Separating them prevents ground bounce from modulating the input stage - essential to maintain <0.1% THD+N and avoid low-frequency oscillation in bridged configurations.

Is the exposed paddle on the TSSOP20 package electrically connected?

Yes - the exposed paddle is internally connected to PGND1/PGND2 and must be soldered to a dedicated thermal pad on the PCB. Failure to connect it results in >20°C higher junction temperature, premature thermal shutdown, and derated output power - violating the θJC = 6°C/W specification.