LM4809 Dual 105mW Headphone Amplifier with Active-Low Shutdown Mode
November 2002
LM4809
Dual 105mW Headphone Amplifier with Active-Low
Shutdown Mode
General Description
The LM4809 is a dual audio power amplifier capable of
delivering 105mW per channel of continuous average power
into a 16Ω load with 0.1% (THD+N) from a 5V power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4809 does not require
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems.
The unity-gain stable LM4809 can be configured by external
gain-setting resistors.
The LM4809 features an externally controlled, active-low,
micropower consumption shutdown mode, as well as an
internal thermal shutdown protection mechanism.
Key Specifications
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THD+N at 1kHz at 105mW continuous average power
into 16Ω
0.1% (typ)
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THD+N at 1kHz at 70mW continuous average power
into 32Ω
0.1% (typ)
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Shutdown Current
0.4µA (typ)
Features
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Active-low shutdown mode
"Click and Pop" reduction circuitry
Low shutdown current
LLP, MSOP, and SO surface mount packaging
No bootstrap capacitors required
Unity-gain stable
Applications
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Headphone Amplifier
Personal Computers
Microphone Preamplifier
PDA’s
Typical Application
20009001
*Refer to the
Application Information
Section for information concerning proper selection of the input and output coupling capacitors.
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer
®
is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
DS200090
www.national.com
NSC [ NATIONAL SEMICONDUCTOR ]
