June 2004
LM4857
Stereo 1.2W Audio Sub-system with 3D Enhancement
General Description
Key Specifications
The LM4857 is an integrated audio sub-system designed for
stereo cell phone applications. Operating on a 3.3V supply, it
combines a stereo speaker amplifier delivering 495mW per
channel into an 8Ω load, a stereo headphone amplifier de-
livering 33mW per channel into a 32Ω load, a mono earpiece
amplifier delivering 43mW into a 32Ω load, and a line output
for an external powered handsfree speaker. It integrates the
audio amplifiers, volume control, mixer, power management
control, and National 3D enhancement all into a single pack-
age. In addition, the LM4857 routes and mixes the stereo
and mono inputs into 16 distinct output modes. The LM4857
is controlled through an I2C compatible interface. Other fea-
tures include an ultra-low current shutdown mode and ther-
mal shutdown protection.
j
POUT, Stereo Loudspeakers, 4Ω, 5V,
1% THD+N (LM4857SP)
1.6W (typ)
1.2W (typ)
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POUT, Stereo Loudspeakers, 8Ω, 5V,
1% THD+N
j
POUT, Stereo Headphones, 32Ω, 5V,
1% THD+N
75mW (typ)
100mW (typ)
495mW (typ)
33mW (typ)
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POUT, Mono Earpiece, 32Ω, 5V,
1% THD+N
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POUT, Stereo Loudspeakers, 8Ω, 3.3V,
1% THD+N
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POUT, Stereo Headphones, 32Ω, 3.3V,
1% THD+N
Boomer audio power amplifiers are designed specifically to
provide high quality output power with a minimal amount of
external components.
j
POUT, Mono Earpiece, 32Ω, 3.3V,
1% THD+N
43mW (typ)
0.06µA (typ)
The LM4857 is available in a 30-bump ITL package and a
28–lead LLP package.
j
Shutdown Current
Features
n Stereo speaker amplifier
n Stereo headphone amplifier
n Mono earpiece amplifier
n Mono Line Output for external handsfree carkit
n Independent Left, Right, and Mono volume controls
n National 3D enhancement
n I2C compatible interface
n Ultra low shutdown current
n Click and Pop Suppression circuit
n 16 distinct output modes
n Thermal Shutdown Protection
n Available in micro SMD and LLP packages
Applications
n Cell Phones
n PDAs
n Portable Gaming Devices
n Internet Appliances
n Portable DVD/CD/AAC/MP3 players
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS200797
www.national.com