LM4850 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – Mono 1.5 W / Stereo 300 mW Power Amplifier

July 2002
LM4850
Mono 1.5 W / Stereo 300 mW Power Amplifier
General Description
The LM4850 is an audio power amplifier capable of deliver-
ing 1.5W (typ) of continuous average power into a mono 4Ω
bridged-tied load (BTL) with 1% THD+N or 95mW per chan-
nel of continuous average power into stereo 32Ω
single-ended (SE) loads with 1% THD+N, using a 5V power
supply.
The LM4850 can automatically switch between mono BTL
and stereo SE modes utilizing a headphone sense pin. It is
ideal for any system that provides both a monaural speaker
output and a stereo line or headphone output
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4850 does not require
bootstrap capacitors or snubber networks, it is optimally
suited for low-power portable systems.
The LM4850 features an externally controlled, micropower
consumption shutdown mode and thermal shutdown protec-
tion. The unity-gain stable LM4850’s gain is set by external
gain-setting resistors
Note 1: An LM4850LD that has been properly mounted to a circuit board will
deliver 1.9W into 3Ω (at 1% THD+N). The other package options for the
LM4850 will deliver 1.1W into 8Ω (at 1% THD+N). See Application Infor-
mation sections for further information concerning the LM4850LD,
LM4850MM, and LM4850MT.
Key Specifications
n Output Power at 1% THD+N, 1kHz:
n LM4850LD 3Ω BTL
n LM4850LD 4Ω BTL
n LM4850MM, MT 4Ω BTL
n LM4850LD, MM, MT 8Ω BTL
n LM4850LD, MM, MT 8Ω SE
n LM4850LD, MM, MT 32Ω SE
n THD+N at 1kHz, 95mW into 32Ω SE
n Single Supply Operation
n Shutdown Current
1.9W (typ)
1.7W (typ)
1.5W (typ)
1.1W (typ)
300mW (typ)
95mW (typ)
1% (typ)
2.4 to 5.5V
44µA (typ)
Features
n Mono 1.5W BTL or stereo 300mW output
n Headphone sense
n “Click and pop” suppression circuitry
n No bootstrap capacitors required
n Thermal shutdown protection
n Unity-gain stable
n LLP, TSSOP, and MSOP packaging
Applications
n Portable computers
n Desktop computers
n PDA’s
n Handheld games
Typical Application
20001031
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200010
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