LM4673 - Filterless, 2.65W, Mono, Class D Audio Power Amplifier

The LM4673 is a single supply, high efficiency, 2.65W, mono, Class D audio amplifier. A low noise, filterless PWM architecture eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design.

The LM4673 is designed to meet the demands of mobile phones and other portable communication devices. Operating on a single 5V supply, it is capable of driving a 4Ω speaker load at a continuous average output of 2.1W with less than 1% THD+N. Its flexible power supply requirements allow operation from 2.4V to 5.5V.

The LM4673 has high efficiency with speaker loads compared to a typical Class AB amplifier. With a 3.6V supply driving an 8Ω speaker, the IC's efficiency for a 100mW power level is 80%, reaching 88% at 400mW output power.

The LM4673 features a low-power consumption shutdown mode. Shutdown may be enabled by driving the Shutdown pin to a logic low (GND).

The gain of the LM4673 is externally configurable which allows independent gain control from multiple sources by summing the signals. Output short circuit and thermal overload protection prevent the device from damage during fault conditions.

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• Mono Class D Operation
• No Output Filter Required for Inductive Loads
• Externally Configurable Gain
• Very Fast Turn On Time: 17μs (typ)
• Minimum External Components
• "Click and Pop" Suppression Circuitry
• Micro-Power Shutdown Mode
• Available in Space-Saving 0.4mm Pitch DSBGA and WSON Packages

Key Specifications

• Efficiency at 3.6V, 400mW into 8Ω Speaker 88% (typ)
• Efficiency at 3.6V, 100mW into 8Ω Speaker 80% (typ)
• Efficiency at 5V, 1W into 8Ω Speaker 86% (typ)
• Quiescent Current, 3.6V Supply 2.1mA (typ)
• Total Shutdown Power Supply Current
  0.01µA (typ)
• Single Supply Range 2.4V to 5.5V
• PSRR, f = 217Hz 78dB

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