Monolithic Power Systems Inc. MP7748DF-LF-Z

Overview

MP7748DF-LF-Z from Monolithic Power Systems is a 2×20W stereo single-ended or 50W mono bridge-tied-load (BTL) Class D audio amplifier IC with integrated 250mΩ MOSFETs, programmable undervoltage protection (UVP), and startup/shutdown pop elimination. It operates from 9.5V to 36V, delivers 0.02% THD+N at 1W into 8Ω (SE), and supports thermal/short-circuit protection in TSSOP28-EP package for flat-panel TV and multimedia computer audio subsystems.

For engineers reviewing the MP7748DF-LF-Z datasheet, MP7748DF-LF-Z pinout, MP7748DF-LF-Z application, or MP7748DF-LF-Z equivalent, this page provides verified electrical specs, dual-channel enable control logic, BTL vs. SE output configuration trade-offs, UVP threshold programming method, and real-world noise floor (103µV SE / 140µV BTL) for audio system integration.

Technical Context

The MP7748 employs MPS' proprietary Analog Adaptive Modulation™ (AAM™) topology to achieve high linearity and fast transient response while operating on a single supply. Its dual-channel architecture features independent EN1/EN2 enable inputs, UVP1/UVP2 pins for per-channel shutdown voltage programming, and TIMER1/TIMER2 pins for adjustable pop-elimination slew rate via external capacitors.

Each channel integrates matched 250mΩ N-channel power MOSFETs in half-bridge configuration with bootstrap gate drive (BST1/BST2), supporting both single-ended (SE) and bridge-tied-load (BTL) output topologies. The internal VDD/2 reference (REF1/REF2) sets DC bias for AC-coupled inputs, and the 600kHz typical idle switching frequency balances efficiency and EMI performance.

Key Specifications

Pinout & Package

TSSOP28-Exposed Pad package with thermal pad soldered to PCB ground plane for enhanced heat dissipation (θJC = 6°C/W). Pin count: 28 leads + exposed thermal pad.

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, MP7748DF-LF-Z offers superior analog input flexibility, user-adjustable UVP thresholds, and lowest noise floor (103µV) among the three - making it optimal for analog-source multimedia systems requiring robust brown-out handling and high SNR.

Availability

MP7748DF-LF-Z is available at Aetrix Electronics and suitable for flat panel television audio, portable docking station subsystems, and multimedia computer speaker amplification requiring stable component supply and RoHS-compliant packaging.

Supply support for MP7748DF-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 mixed-signal ICs for power management and audio applications, headquartered in Kirkland, WA.

The MP7748 belongs to MPS' Class D Audio Amplifier product line, designed specifically for high-efficiency, low-noise stereo and mono audio output stages in space-constrained consumer electronics with single-supply operation.

FAQ

What is the minimum recommended input coupling capacitor value for MP7748DF-LF-Z?

The input coupling capacitor (CIN) corner frequency must be below the audio passband. For a 20Hz lower cutoff and 10kΩ input impedance, CIN ≥ 1/(2π × 20Hz × 10kΩ) ≈ 0.8µF. A 1µF X7R ceramic capacitor is recommended to ensure stability and low distortion across temperature.

Can MP7748DF-LF-Z operate in mono BTL mode with a single 12V supply?

Yes - MP7748DF-LF-Z supports BTL mode down to 9.5V VDD. At 12V, it delivers 15W into 6Ω (10% THD+N) in BTL configuration. Efficiency drops to ~82%, and thermal design must accommodate higher junction temperature due to reduced headroom.

How is the default 8.4V UVP threshold set when UVP1/UVP2 pins are left unconnected?

When UVP1 and UVP2 are NC, internal 500kΩ and 550kΩ resistors form a voltage divider across VDD, producing a reference that triggers shutdown at 8.4V (rising) with 0.3V hysteresis. No external components are required for basic brown-out protection.

What LC filter values are recommended for 24V/4Ω SE operation?

For 24V/4Ω SE, use 10µH inductors and 220µF electrolytic output coupling capacitors. The LC corner frequency should be ~20kHz (e.g., 10µH + 10µF yields ~50kHz), ensuring full audio bandwidth while suppressing switching noise above 300kHz.

Does MP7748DF-LF-Z require external bootstrap diodes for BST1/BST2 operation?

No - MP7748DF-LF-Z integrates internal bootstrap charging circuitry. A 0.1µF ceramic capacitor from BST1 to SW1 (and BST2 to SW2) is sufficient; no external diode is needed, simplifying layout and improving reliability.

What is the maximum allowable thermal pad copper area for TSSOP28-EP package?

The exposed thermal pad must connect to a solid PCB ground plane with ≥4 thermal vias (0.3mm diameter) to inner/ground layers. Total copper area should be ≥25mm²; exceeding this improves θJA but does not reduce θJC below the specified 6°C/W.

How does the AAM™ modulation differ from standard fixed-frequency Class D topologies?

AAM™ dynamically adjusts switching frequency based on input signal amplitude and load conditions, reducing intermodulation distortion and improving PSRR. Unlike fixed-frequency PWM, it maintains >90dB SNR across 20Hz–20kHz without external compensation networks.