LM4864M - Bridged Audio Power Amplifier

Overview

The LM4864M is a high-performance, bridged audio power amplifier designed to deliver superior sound quality with minimal external components. This IC is capable of providing 300 mW of continuous average power into an 8Ω load, making it ideal for portable audio applications. The device integrates advanced features such as low power consumption shutdown mode and thermal shutdown protection, ensuring both efficiency and reliability in demanding environments.

With its compact design and robust performance, the LM4864M is widely used in consumer electronics, including mobile phones, portable media players, and other battery-operated audio devices. Its bridged output configuration eliminates the need for bulky coupling capacitors, reducing both cost and board space.

Features

• High Output Power: Delivers 300 mW into an 8Ω load with minimal distortion.
• Low Power Consumption: Features an externally controlled shutdown mode to minimize power usage when idle.
• Thermal Shutdown Protection: Built-in protection mechanism prevents damage from overheating.
• Bridged Output Configuration: Eliminates the need for output coupling capacitors, reducing component count and cost.
• Wide Supply Voltage Range: Operates from 2.0V to 5.5V, making it suitable for battery-powered applications.
• Improved PSRR (Power Supply Rejection Ratio): Reduces noise and interference from the power supply.
• Surface-Mount Package: Available in a space-saving MSOP package for compact PCB designs.

Applications

The LM4864M is designed for a variety of audio applications, particularly where space and power efficiency are critical. Key applications include:

• Portable Audio Devices: Mobile phones, MP3 players, and portable gaming systems.
• Consumer Electronics: Tablets, laptops, and handheld multimedia devices.
• Personal Communication Devices: Bluetooth headsets, intercoms, and voice recorders.
• Embedded Systems: Audio feedback in industrial and automotive applications.

Electrical Characteristics

The following table summarizes the key electrical specifications of the LM4864M under typical operating conditions (V_DD = 5V, T_A = 25°C, unless otherwise noted).

Absolute Maximum Ratings

• Supply Voltage (V_DD): 6V
• Output Power (P_OUT): 300 mW (continuous, 8Ω)
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -65°C to +150°C

Key Performance Parameters

• Total Harmonic Distortion + Noise (THD+N): < 1% (at 300 mW, 1 kHz)
• Quiescent Current (I_Q): 4 mA (typical, no load)
• Shutdown Current (I_SD): 0.1 µA (typical)
• PSRR (Power Supply Rejection Ratio): 60 dB (at 217 Hz)
• Gain Bandwidth Product: 1.2 MHz (typical)

Package Information

The LM4864M is available in an 8-pin MSOP (Mini Small Outline Package) with the following mechanical specifications:

• Package Type: MSOP-8
• Dimensions: 3 mm x 3 mm (body size)
• Pin Pitch: 0.65 mm
• Lead Material: Matte Tin (Sn) plating for improved solderability.

Pin Configuration

• Pin 1 (SHUTDOWN): Active-low shutdown control input.
• Pin 2 (V_DD): Positive power supply input.
• Pin 3 (IN-): Inverting input for the amplifier.
• Pin 4 (IN+): Non-inverting input for the amplifier.
• Pin 5 (GND): Ground reference.
• Pin 6 (OUT+): Positive bridged output.
• Pin 7 (NC): No connection (reserved for future use).
• Pin 8 (OUT-): Negative bridged output.

Conclusion

The LM4864M is a versatile and efficient audio power amplifier that combines high performance with low power consumption, making it an excellent choice for portable and battery-operated audio applications. Its integrated protection features, compact package, and bridged output configuration provide designers with a reliable and space-saving solution for high-quality audio amplification.