LM4809 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 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
n THD+N at 1kHz at 105mW continuous average power
into 16Ω
0.1% (typ)
n THD+N at 1kHz at 70mW continuous average power
into 32Ω
0.1% (typ)
n Shutdown Current
0.4µA (typ)
Features
n Active-low shutdown mode
n "Click and Pop" reduction circuitry
n Low shutdown current
n LLP, MSOP, and SO surface mount packaging
n No bootstrap capacitors required
n Unity-gain stable
Applications
n Headphone Amplifier
n Personal Computers
n Microphone Preamplifier
n 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
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