Monolithic Power Systems Inc. MP7751GF-Z

Overview

MP7751GF-Z 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 zero-signal shutdown, and TSSOP-28 EP packaging. It targets compact high-efficiency audio systems requiring low THD+N (0.08%), 92% efficiency at 12V/8Ω, and robust protection including thermal shutdown, short-circuit detection, and under-voltage lockout.

For engineers reviewing the MP7751GF-Z datasheet, MP7751GF-Z pinout, MP7751GF-Z application, or MP7751GF-Z equivalent, key selection criteria include its fixed 260–360kHz switching frequency, differential input architecture with programmable gain (20–36dB), open-drain /FAULT and InAbsence outputs, and precise PLIMIT-based anti-clipping control for speaker protection in battery-powered and energy-conscious designs.

Technical Context

The MP7751GF-Z implements a fixed-frequency PWM modulation scheme with stereo BTL output stage using eight internal N-channel MOSFETs-two per half-bridge-with bootstrap gate drive (BST1A/BST1B/BST2A/BST2B) enabling full enhancement of high-side switches. Its closed-loop gain is digitally selectable via GAIN0/GAIN1 pins across four discrete settings (20/26/32/36dB), while input common-mode voltage is internally biased at 2.5V for differential operation.

It integrates analog signal absence detection with user-adjustable delay (via external capacitor on Cap_D pin), a virtual rail-based power limiter (PLIMIT pin sets peak output voltage as 8× applied voltage), and coordinated fault management: /FAULT asserts low on overtemperature (>150°C trip, 130°C hysteresis) or overcurrent, forcing all outputs to high-impedance state with controlled restart sequence to suppress pop noise.

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, JEDEC MO-153 compliant.

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-Z offers optimal balance of analog simplicity, integrated protection (InAbsence, PLIMIT, /FAULT), and compact TSSOP-28 EP packaging-making it ideal for cost-sensitive, space-constrained stereo amplifiers where digital control is unnecessary and autonomous power management is critical.

Availability

MP7751GF-Z is available at Aetrix Electronics and suitable for TV audio subsystems, active speaker designs, home theater front channels, and DVD/Blu-ray receiver applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.

Supply support for MP7751GF-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 core expertise in DC/DC conversion, LED drivers, motor drivers, and Class D audio amplifiers.

The MP7751 belongs to MPS' fully integrated Class D audio amplifier product line, engineered specifically for space-constrained consumer audio systems demanding high efficiency, low EMI, and autonomous power management without external controllers.

FAQ

What is the maximum continuous output power per channel for MP7751GF-Z?

The MP7751GF-Z delivers up to 20W per channel into an 8Ω load at 18V supply with 10% THD+N, verified per typical operating conditions in the datasheet. At 24V, peak output reaches 36W total (18W per channel), but thermal limits constrain sustained operation to 20W/channel unless heatsinking is enhanced. The adjustable PLIMIT pin allows designers to cap output to protect speakers or meet regulatory power limits.

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

The PLIMIT pin sets a "virtual rail" equal to 8× the applied voltage, limiting peak-to-peak output swing to prevent clipping. For example, 1.44V on PLIMIT caps output at 23.6Vpp, yielding ~10W into 8Ω. Apply 0.5V–5.5V (within AVCC range); connect to AVCC for no limiting or use a resistor divider from AVCC to AGND. A 1μF capacitor to ground is mandatory for stability.

Can MP7751GF-Z operate with single-ended inputs, and what is the input impedance?

Yes-though optimized for differential inputs (IN1A/IN1B, IN2A/IN2B), it accepts single-ended signals referenced to AGND with AC coupling. Input impedance varies with gain setting: 20kΩ (36dB), 30kΩ (32dB), 50kΩ (26dB), or 75kΩ (20dB), with ±20% part-to-part tolerance. Minimum guaranteed impedance is 16kΩ, guiding coupling capacitor selection for corner frequencies below 20Hz.

What thermal protection mechanisms are implemented, and how does recovery work?

MP7751GF-Z includes junction temperature sensing with 150°C shutdown and 130°C hysteresis. When tripped, all MOSFETs turn off and /FAULT pulls low. Recovery requires die temperature to fall below 130°C, followed by full re-enable sequence via EN pin-preventing pop noise and ensuring safe restart. No latch-up occurs; operation resumes automatically once thermal margin is restored.

Is the TSSOP-28 EP package lead-free and RoHS-compliant?

Yes-MP7751GF-Z is fully lead-free and complies with the EU RoHS directive. The exposed thermal pad (EP) must be soldered to a large PCB copper area for thermal performance; MPS specifies minimum pad dimensions and solder stencil guidelines in the package drawing. All plating meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL3).

How is the automatic shutdown triggered, and can the delay be adjusted?

Automatic shutdown activates when no audio signal exceeds 2–8mV RMS for longer than the delay set by capacitor on Cap_D (Pin 14). Delay time ≈ 1.6×10⁸ × R × C seconds, where R = 10MΩ internal pull-up. A 100nF capacitor yields ~1.6s delay; 1μF gives ~16s. Connect Cap_D to AGND to disable the feature entirely-useful in always-on applications like public address systems.

What are the recommended LC filter design constraints for BTL operation?

For BTL configuration, use symmetric LC filters per channel with characteristic frequency f₀ = 1/(2π√(L_FC_F)) between 30–50kHz. Maintain Q-factor 0.7–1.4 using speaker impedance (R_L) per Q = R_L/√(L_F/C_F). Select film capacitors and gapped ferrite/toroidal inductors rated for ≥5A peak current; orient all inductors identically to suppress crosstalk.