LM4673 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Filterless, 2.65W, Mono, Class D Audio Power Amplifier

December 2005
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 archi-
tecture eliminates the output filter, reducing external compo-
nent count, board area consumption, system cost, and sim-
plifying 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 operation from 2.4V to 5.5V.
The LM4673 has high efficiency with speaker loads com-
pared 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 over-
load protection prevent the device from damage during fault
conditions.
Key Specifications
j Efficiency at 3.6V, 400mW into 8Ω speaker 88% (typ)
j Efficiency at 3.6V, 100mW into 8Ω speaker 80% (typ)
j Efficiency at 5V, 1W into 8Ω speaker
86% (typ)
j Quiescent current, 3.6V supply
2.1mA (typ)
j Total shutdown power supply current 0.01µA (typ)
j Single supply range
2.4V to 5.5V
j PSRR, f = 217Hz
78dB
Features
n Mono Class D Operation
n No output filter required for inductive loads
n Externally configurable gain
n Very fast turn on time: 17µs (typ)
n Minimum external components
n "Click and pop" suppression circuitry
n Micro-power shutdown mode
n Available in space-saving 0.4mm pitch micro SMD and
LLP^Tm (Future Product) packages
Applications
n Mobile phones
n PDAs
n Portable electronic devices
Typical Application
201522J3
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation DS201522
www.national.com