Monolithic Power Systems Inc. MP7748DF-LF

Overview

MP7748DF-LF from Monolithic Power Systems is a stereo Class D audio amplifier IC delivering 20W per channel into 4Ω in single-ended configuration or 50W into 6Ω in bridge-tied-load mode at 24V VDD, featuring integrated 250mΩ MOSFETs, programmable undervoltage protection (UVP), and startup/shutdown pop elimination for consumer audio systems.

For engineers reviewing the MP7748DF-LF datasheet, MP7748DF-LF pinout, MP7748DF-LF application, or MP7748DF-LF equivalent, this page provides verified electrical specifications, thermal performance data, TSSOP28-Exposed package layout guidance, and real-world BTL/SE configuration trade-offs - all critical for high-fidelity, high-efficiency audio subsystem design.

Technical Context

The MP7748DF-LF implements MPS's proprietary Analog Adaptive Modulation™ (AAM) topology with variable-frequency PWM control, enabling high linearity and fast transient response without external compensation. It integrates dual independent Class D channels, each with dedicated bootstrap (BST1/BST2), enable (EN1/EN2), and UVP (UVP1/UVP2) pins for flexible power sequencing and fault management.

Each channel operates from a single 9.5V–36V supply and includes internal thermal shutdown (150°C trip), short-circuit protection (4.5A current limit), and analog reference outputs (REF1/REF2 = VDD/2) for SE biasing. The device supports both stereo SE and mono BTL topologies via external LC filter configuration and gain-setting resistor networks.

Key Specifications

Pinout & Package

The MP7748DF-LF is housed in a thermally enhanced TSSOP28-Exposed Pad package. The exposed pad must be soldered to a PCB ground plane for optimal thermal dissipation (θJC = 6°C/W). Pin numbering follows standard TSSOP top-view orientation with pin 1 at bottom-left corner.

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 MAX9744, the MP7748DF-LF uniquely balances analog input simplicity, BTL/SE configurability, and hardware-programmable UVP - making it optimal for hybrid analog/digital consumer electronics where supply voltage range varies across product SKUs.

Availability

MP7748DF-LF is available at Aetrix Electronics and suitable for portable docking stations, flat panel monitors, and home stereo systems requiring stable component supply across multi-year production cycles.

Supply support for MP7748DF-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 over two decades of leadership in DC/DC converters, LED drivers, and Class D audio amplifiers.

The MP7748 belongs to MPS's Class D Audio Amplifier product line, engineered specifically for high-efficiency, low-noise stereo and mono audio output in space-constrained consumer electronics - emphasizing thermal robustness, pop-free operation, and single-supply flexibility.

FAQ

What is the maximum safe operating voltage for MP7748DF-LF?

The absolute maximum supply voltage (VDD) is 40V, but the recommended operating range is 9.5V to 36V. Exceeding 36V risks permanent damage to internal MOSFETs and gate drivers. At 36V, the device delivers up to 50W in BTL mode into 6Ω with 91% efficiency, provided thermal limits (TJ ≤ 125°C) are maintained via proper PCB copper area and exposed pad soldering.

How does the programmable UVP function work without external components?

When UVP1 and UVP2 pins are left unconnected (NC), internal resistor dividers set the rising VDD shutdown threshold to 8.4V with 0.3V hysteresis. This default behavior eliminates need for external resistors in basic applications. For custom thresholds (e.g., 12V cutoff), connect UVP1/UVP2 to a resistor divider from VDD to GND, calculating RH and RL using VDD_shutdown = 4 × (RH + RL)/RL per datasheet Equation 1.

Can MP7748DF-LF drive 8Ω speakers in stereo SE mode?

Yes - it delivers 10.6W per channel into 8Ω at 24V VDD and 10% THD+N, with THD+N of 0.02% at 1W. This meets standard line-output power requirements for near-field desktop speakers. For higher output, configure one channel in BTL mode to drive a single 8Ω woofer with 40W output, while the other remains in SE for tweeter or center channel.

What LC filter values are recommended for BTL operation at 24V?

Per Table 2 in the datasheet, for 24V BTL operation with 15V/V gain, use CINT1 = 3.9nF for ~580kHz idle switching frequency. Recommended LC values are 1.5µH inductors (gapped ferrite core, 5A saturation current) and 220µF film capacitors per channel. Q-factor must be maintained between 0.7–1.0 using RLOAD = 6Ω or 8Ω to prevent passband peaking or excessive ripple.

Is thermal shutdown reversible, and how long does recovery take?

Yes - thermal shutdown is fully automatic and reversible. When junction temperature exceeds 150°C, the device disables both channels and enters hiccup mode: it attempts restart every ~500ms until TJ falls below 120°C (30°C hysteresis). Full recovery typically occurs within 2–5 seconds after ambient cooling, with no external intervention required - ensuring robust operation in enclosed enclosures.

Does MP7748DF-LF support I²S or digital audio inputs?

No - MP7748DF-LF accepts only analog differential inputs (IN1/IN2 referenced to REF1/REF2). It lacks digital interfaces, clock inputs, or internal DACs. For digital audio systems, pair it with an external stereo DAC (e.g., PCM5102A) whose analog outputs feed IN1/IN2. This analog-input architecture simplifies EMI filtering and avoids jitter-sensitive digital timing paths.

What is the purpose of the exposed pad, and how should it be connected?

The exposed pad is electrically and thermally connected to PGND and serves as the primary heat dissipation path (θJC = 6°C/W). It must be soldered to a solid internal or bottom-layer PCB ground plane covering ≥100mm², with ≥4 thermal vias (0.3mm diameter) connecting to inner ground layers. Failure to properly connect the pad causes junction temperature to exceed 125°C at <15W output, triggering thermal shutdown.