LM4673_07 Datasheet, PDF (1/24 Pages) National Semiconductor (TI) – Filterless, 2.65W, Mono, Class D Audio Power Amplifier

November 1, 2007
LM4673 
Filterless, 2.65W, Mono, Class D Audio Power Amplifier
General Description
The LM4673 is a single supply, high efficiency, 2.65W, mono,
Class D audio amplifier. A low noise, filterless PWM architec-
ture 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. Operat-
ing 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 op-
eration 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 al-
lows independent gain control from multiple sources by sum-
ming the signals. Output short circuit and thermal overload
protection prevent the device from damage during fault con-
ditions.
Key Specifications
■ 
Efficiency at 3.6V, 400mW into 8Ω speaker
■ 
Efficiency at 3.6V, 100mW into 8Ω speaker
■ 
Efficiency at 5V, 1W into 8Ω speaker
■ Quiescent current, 3.6V supply
■ 
Total shutdown power supply current
■ Single supply range
■ PSRR, f = 217Hz
88% (typ)
80% (typ)
86% (typ)
2.1mA (typ)
0.01µA (typ)
2.4V to 5.5V
78dB
Features
■ ^{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 micro SMD and}
LLP^Tm packages
Applications
■ ^{Mobile phones}
■ ^PDAs
■ ^{Portable electronic devices}
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