Monolithic Power Systems Inc. MP7782DF-LF

Overview

MP7782DF-LF from Monolithic Power Systems is a mono, 50W Class D audio amplifier in TSSOP20F package with exposed thermal pad, integrating four 180mΩ MOSFETs for bridged-tied-load (BTL) operation into 6Ω speakers at 24V supply, delivering 90% efficiency and 0.06% THD+N at 1W - deployed in home stereo and multimedia computer audio subsystems.

For engineers reviewing the MP7782DF-LF datasheet, MP7782DF-LF pinout, MP7782DF-LF application, or MP7782DF-LF equivalent, key selection criteria include its ADAM™ variable-frequency modulation topology, dual-channel full-bridge output structure, integrated thermal shutdown and short-circuit protection, and compatibility with single-supply 9.5–24V systems requiring low-noise, high-efficiency audio amplification.

Technical Context

The MP7782DF-LF implements Monolithic Power's proprietary ADAM™ (Analog Digital Adaptive Modulation) topology - a variable-frequency PWM scheme enabling >60dB PSRR, fast transient response, and stable operation without external compensation. It operates as a true mono BTL amplifier with two independent half-bridge channels (SW1/PGND1/VDD1/BS1 and SW2/PGND2/VDD2/BS2), each driving one side of the speaker load differentially.

Feedback is implemented via dual FB1/FB2 pins tied in pairs to sense both switching nodes and input signal paths, enabling closed-loop stability across the full 20Hz–20kHz audio band. The device supports mute/standby mode via EN pin with 1.4V rising threshold and integrates click-and-pop suppression during power-up/down sequences.

Key Specifications

Pinout & Package

TSSOP20F thermally enhanced package with exposed copper pad (pin 0) for PCB-level heat dissipation; θ_JA = 40°C/W, θ_JC = 6°C/W on 1″² 1oz copper - requires soldered thermal pad connection to inner ground plane for continuous 50W operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP7748S and TAS5756M, MP7782DF-LF offers lowest component count and simplest analog-only implementation for fixed-gain, high-power mono BTL applications - ideal for cost-sensitive, high-volume consumer audio where design freeze and long-term availability are prioritized over configurability.

Availability

MP7782DF-LF is available at Aetrix Electronics and suitable for home stereo amplifiers, smart television audio subsystems, and multimedia computer speaker drivers requiring stable component supply and long-term industrial availability.

Supply support for MP7782DF-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 core expertise in DC/DC conversion, LED drivers, and Class D audio amplification.

The MP7782 belongs to MPS' second-generation fully integrated Class D audio amplifier product line, engineered to replace discrete MOSFET-based designs in space-constrained consumer audio equipment while maintaining AB-class fidelity.

FAQ

What is the maximum continuous output power of MP7782DF-LF into an 8Ω load?

The MP7782DF-LF delivers 40W continuous output into 8Ω at 10% THD+N with 24V supply, as specified in the Operating Specifications table. This reflects reduced power capability versus the 50W into 6Ω rating due to higher load impedance limiting current delivery while maintaining thermal safety margins.

Can MP7782DF-LF operate from a 12V supply, and what output power is achievable?

Yes - MP7782DF-LF supports 9.5V to 24V operation. At 12V supply, maximum output drops to approximately 12W into 6Ω (calculated from P = V²/R with headroom for BTL swing), sufficient for compact soundbars or secondary audio zones where thermal constraints limit sustained power.

Is an external LC filter required, and what are the critical design constraints?

Yes - dual identical LC filters (one per SW pin) are mandatory to reconstruct analog audio from PWM. Inductor value must yield characteristic frequency f₀ ≈ 1/(2π√(LC)) between 30–50kHz; Q factor must be 0.7–2.0 to avoid peaking or excessive noise, with film capacitors and gapped ferrite inductors recommended for low distortion.

How does the ADAM™ modulation topology improve PSRR compared to fixed-frequency Class D designs?

ADAM™ uses variable-frequency adaptive modulation that dynamically adjusts switching frequency based on input signal and supply conditions, decoupling audio-band noise from switching harmonics. This yields 60dB PSRR at 1kHz - 10–15dB higher than typical fixed-frequency modulators - by rejecting supply ripple before it modulates the audio carrier.

What thermal management is required for continuous 50W operation?

Continuous 50W output requires soldering the exposed thermal pad to a ≥2″² inner-layer copper pour connected to ≥4 thermal vias (0.3mm diameter) to internal ground planes. Without this, junction temperature exceeds 150°C within seconds; with proper layout, θ_JA drops from 40°C/W to ≤25°C/W enabling sustained operation.

Why are FB1 and FB2 pins duplicated (pins 2/7 and 3/8), and how must they be connected?

Duplication improves noise immunity and routing flexibility: FB1 pins (3,8) must be shorted together and connected to SW1 and the positive input path; FB2 pins (2,7) must be shorted together and connected to SW2 and the negative input path. This maintains matched feedback impedance and minimizes common-mode error in differential sensing.

Does MP7782DF-LF support parallel operation for higher power or stereo output?

No - MP7782DF-LF is strictly a mono BTL amplifier. It cannot be paralleled due to lack of synchronization inputs or master/slave configuration. For stereo, two MP7782DF-LF units are required, with separate input signals and independent LC filtering per channel.