Monolithic Power Systems Inc. MP7751GF

Overview

MP7751GF from Monolithic Power Systems is a 26V, stereo bridge-tied-load (BTL) Class D audio amplifier IC delivering up to 20W per channel into 8Ω at 18V supply, featuring integrated 240mΩ MOSFETs, adjustable power limiting, automatic shutdown on zero-input detection, and TSSOP-28 EP packaging. It targets compact, high-efficiency audio systems requiring low-THD, high PSRR, and robust thermal/short-circuit protection.

For engineers reviewing the MP7751GF datasheet, MP7751GF pinout, MP7751GF application, or MP7751GF equivalent, key selection criteria include its fixed 260–360kHz switching frequency, ±5A peak output current, 92% efficiency at 12V/8Ω, differential input architecture for EMI resilience, and programmable gain (19–37dB) via GAIN0/GAIN1 pins.

Technical Context

The MP7751GF implements a fixed-frequency PWM modulation scheme with stereo BTL output stage using eight integrated N-channel MOSFETs-four per channel-with bootstrap gate drive (BST1A/BST1B/BST2A/BST2B) enabling full enhancement of high-side switches. Its closed-loop gain is set digitally via two binary inputs (GAIN0/GAIN1), yielding four discrete gain options from 19dB to 37dB.

It integrates analog signal absence detection (via InAbsence and Cap_D pins), adjustable power limiting (PLIMIT pin sets virtual rail at 8× applied voltage), and open-drain fault reporting (/FAULT) triggered by overtemperature (>150°C) or overcurrent events. Startup/shutdown pop elimination is achieved through controlled enable sequencing and internal soft-start logic.

Key Specifications

Pinout & Package

TSSOP-28 EP package with exposed thermal pad (EP) for enhanced heat dissipation; 0.65mm pitch, 9.7mm × 4.4mm body size; requires solder paste stencil optimization and thermal via array under EP for reliable operation at full power.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TAS5756M and TPA3116D2, MP7751GF offers optimal balance of analog simplicity, thermal efficiency, and intelligent power management - making it ideal for cost-constrained, space-limited, and battery-aware stereo audio systems where full digital processing is unnecessary.

Availability

MP7751GF is available at Aetrix Electronics and suitable for TV audio subsystems, active speaker production, and home theater soundbar manufacturing requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MP7751GF 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 converters, LED drivers, and Class D audio amplifiers.

The MP7751GF belongs to MPS' fully integrated Class D audio amplifier product line, designed specifically for compact, high-efficiency stereo audio systems requiring minimal external components, robust protection, and intelligent power management.

FAQ

What is the maximum allowable supply voltage for MP7751GF?

The absolute maximum supply voltage (PVCC) is +30V, but the recommended operating range is 5V to 26V. Exceeding 26V risks permanent damage and voids warranty compliance; operation at 24V is typical for 20W/channel output into 8Ω loads with margin for ripple.

How does the PLIMIT pin function, and what voltage should be applied?

The PLIMIT pin sets a "virtual rail" equal to 8× the applied voltage, capping peak-to-peak output swing. For example, 1.44V on PLIMIT limits output to ~23.6Vpp, yielding ~10W into 8Ω. Connect a resistor divider from AVCC (5.5V) to GND, or tie directly to AVCC for full-rail operation.

Can MP7751GF drive 4Ω speakers, and what derating applies?

Yes - MP7751GF supports 4Ω loads with appropriate thermal design. At 12V supply, output drops to ~15W/channel (vs. 9.5W at 8Ω) due to higher current demand; efficiency remains >90%, but junction temperature must stay below 125°C with adequate copper area and thermal vias under the EP pad.

What is the purpose of the Cap_D pin, and how is the delay time calculated?

Cap_D sets the hold time before auto-shutdown after audio signal absence. Delay ≈ 1.6×10⁸ × R × C seconds, where R is internal 1.6MΩ pull-up and C is external capacitor to AGND. A 100nF capacitor yields ~16s delay; grounding Cap_D disables the feature entirely.

Does MP7751GF require external bootstrap diodes?

No - MP7751GF integrates internal bootstrap charging circuitry. External components required per channel are only a ceramic capacitor (0.1–1µF) between each BST pin (e.g., BST1A) and its corresponding SW pin (e.g., SW1A); no diodes or resistors are needed in the bootstrap path.

How is thermal shutdown implemented, and what hysteresis exists?

Thermal shutdown activates at TJ = 150°C, turning off all MOSFETs. Operation resumes only after die temperature falls to 130°C (20°C hysteresis), followed by full soft-start sequence to prevent output pop. This protects against sustained overload or inadequate heatsinking in enclosed enclosures.

What LC filter values are recommended for BTL operation at 20W into 8Ω?

For 260–360kHz switching, use 10µH inductors (gapped ferrite or toroidal) and 1µF film capacitors per channel. Characteristic frequency f₀ ≈ 1/(2π√(LC)) should be ~20kHz; Q-factor must be 0.7–1.4 - achieved with 8Ω load and proper inductor DCR selection to avoid peaking or excessive noise.