Monolithic Power Systems Inc. MPQ7731DF-LF-Z

Overview

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

For engineers reviewing the MPQ7731DF-LF-Z datasheet, MPQ7731DF-LF-Z pinout, MPQ7731DF-LF-Z application, or MPQ7731DF-LF-Z equivalent, key selection factors include its dual-amplifier bridged architecture, AAM® variable-frequency modulation, thermal shutdown (150°C), click/pop suppression, and TSSOP20 exposed-pad package with validated 20-pin terminal mapping.

Technical Context

The MPQ7731DF-LF-Z implements a proprietary Analog Adaptive Modulation (AAM®) topology enabling variable switching frequency (400–600 kHz idle), >60 dB PSRR at 1 kHz, and fast transient response without external compensation. Its dual-channel internal bridge structure drives differential speaker outputs via SW1/SW2 pins while maintaining independent VDD1/VDD2 and PGND1/PGND2 power domains.

It integrates four 180mΩ MOSFETs per channel, short-circuit protection with 5.0 A current limit, and thermal shutdown with 30°C hysteresis. Mute/standby control is implemented through synchronized EN1/EN2 inputs, and bootstrap operation (BS1/BS2) enables high-side gate drive without external charge pumps.

Key Specifications

Pinout & Package

MPQ7731DF-LF-Z is housed in a 20-pin TSSOP package with exposed thermal pad (JEDEC MO-153 compliant), optimized for surface-mount assembly and PCB-level heat dissipation in audio subsystems.

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, MPQ7731DF-LF-Z uniquely combines analog input flexibility, integrated pop suppression, and 30W capability in a single TSSOP20 package - simplifying layout and reducing qualification effort for display OEMs.

Availability

MPQ7731DF-LF-Z 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-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 power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MPQ7731 belongs to MPS's second-generation Class D audio amplifier product line, engineered specifically for space- and thermally constrained visual display systems requiring high-efficiency, low-EMI, and plug-and-play analog audio integration.

FAQ

What is the minimum recommended LC filter cutoff frequency for MPQ7731DF-LF-Z?

The LC filter characteristic frequency should be set between 20 kHz and 50 kHz - high enough to pass full audio bandwidth but low enough to attenuate switching harmonics. For 4Ω loads, typical values are 10 µH inductors and 1 µF film capacitors, yielding ~50 kHz f₀ and Q ≈ 1.1, balancing noise and passband flatness.

Can MPQ7731DF-LF-Z drive an 8Ω speaker, and what is the expected output power?

Yes - at VDD = 16.5V, it delivers up to 17W into 8Ω with THD+N ≤ 0.1% at 1W. Power scales approximately linearly with load impedance; efficiency remains above 88% at 10W output, making it suitable for higher-impedance home stereo modules.

How does the AAM® modulation improve PSRR compared to fixed-frequency Class D amplifiers?

AAM® dynamically adjusts switching frequency in response to supply voltage and load, preventing beat frequencies with power supply ripple. This yields >60 dB PSRR at 1 kHz - 15–20 dB better than fixed-frequency counterparts - eliminating need for ultra-low-noise LDOs in display power trees.

Is the exposed thermal pad on the TSSOP20 package required to be soldered to PCB ground?

Yes - the exposed paddle must be soldered to a dedicated thermal pad connected to ≥4 internal copper layers and multiple vias to inner ground planes. Thermal resistance drops from θJA = 40°C/W (unsoldered) to ≤22°C/W when properly connected, enabling full 30W output without derating.

What happens if EN1 and EN2 are not tied together?

Driving EN1 and EN2 independently causes asymmetric channel enable timing, leading to large DC offset at the speaker terminals and potential pop transients or latch-up. The datasheet explicitly requires EN1 and EN2 to be shorted externally - no functional benefit exists from separate control.

Does MPQ7731DF-LF-Z support single-ended input configuration?

No - it requires differential input signals. However, single-ended sources can be interfaced using a simple resistive divider to bias PIN1/NIN1 at VDD/2 and AC-coupling the signal to one input while grounding the other through matching impedance, though this degrades CMRR and increases THD+N by ~0.05%.

What is the maximum allowable VDD slew rate during power-up to avoid latch-up?

VDD must ramp monotonically at ≥1 V/ms but ≤10 V/ms. Faster slew rates risk false triggering of internal bandgap references; slower rates extend time in undefined logic states. A 100 µF bulk capacitor with 1 Ω series resistor achieves optimal ramping for 12V supplies.