LM4900
265mW at 3.3V Supply Audio Power Amplifier with
Shutdown Mode
General Description
The LM4900 is a bridged audio power amplifier capable of
delivering 265mW of continuous average power into an 8
load with 1% THD+N from a 3.3V power supply.
Boomer audio power amplifiers were designed specifically
to provide high quality output power from a low supply volt-
age while requiring a minimal amount of external compo-
nents. Since the LM4900 does not require output coupling
capacitors, bootstrap capacitors or snubber networks, it is
optimally suited for low-power portable applications.
The LM4900 features an externally controlled, low power
consumption shutdown mode, and thermal shutdown protec-
tion.
The closed loop response of the unity-gain stable LM4900
can be configured by external gain-setting resistors.
Key Specifications
j THD+N at 1kHz for 265mW continuous
average output power into 8
,
V
DD = 3.3V
1.0% (max)
j THD+N at 1kHz for 675mW continuous
average output power into 8
,
V
DD = 5V
1.0% (max)
j Shutdown current
0.1A (typ)
Features
n
MSOP, LLP, and SOP packaging
n
No output coupling capacitors, bootstrap capacitors, or
snubber circuits are necessary
n
Thermal shutdown protection circuitry
n
Unity-gain stable
n
External gain configuration capability
n
Latest generation "click and pop" suppression circuitry
Applications
n
Cellular phones
n
PDA’s
n
Any portable audio application
Typical Application
Boomer is a registered trademark of National Semiconductor Corporation.
20006401
FIGURE 1. Typical Audio Amplifier Application Circuit
September 2001
LM4900
265mW
at
3.3V
Supply
Audio
Power
Amplifier
with
Shutdown
Mode
2004 National Semiconductor Corporation
DS200064
www.national.com