LM4873 Dual 2.1W Audio Amplifier Plus Stereo Headphone Function
April 2000
LM4873
Dual 2.1W Audio Amplifier Plus Stereo Headphone
Function
General Description
The LM4873 is a dual bridge-connected audio power ampli-
fier which, when connected to a 5V supply, will deliver 2.1W
to a 4Ω load (Note 1) or 2.4W to a 3Ω load (Note 2)with less
than 1.0% THD+N. In addition, the headphone input pin al-
lows the amplifiers to operate in single-ended mode to drive
stereo headphones. A Mux Control pin toggles between the
two stereo sets of amplifier inputs, allowing for two select-
able amplifier closed-loop responses.
Boomer audio power amplifiers were designed specifically to
provide high quality output power from a surface mount
package while requiring few external components. To sim-
plify audio system design, the LM4873 combines dual bridge
speaker amplifiers and stereo headphone amplifiers on one
chip.
The LM4873 features an externally controlled, low-power
consumption shutdown mode, a stereo headphone amplifier
mode, and thermal shutdown protection. It also utilizes cir-
cuitry to reduce “clicks and pops” during device turn-on.
Note 1:
An LM4873MTE-1 which has been properly mounted to the circuit
board will deliver 2.1W into 4Ω. The other package options for the LM4873
will deliver 1.1W into 8Ω. See the Application Information section for
LM4873MTE-1 usage information.
Note 2:
An LM4873MTE-1 which has been properly mounted to the circuit
board and forced-air cooled will deliver 2.4W into 3Ω.
Key Specifications
n
P
O
at 1% THD+N
into 3Ω (LM4873MTE-1)
into 4Ω (LM4873MTE-1)
into 4Ω (LM4873MTE)
into 8Ω (LM4873)
n
Single-ended mode - THD+N
at 75mW into 32Ω
n
Shutdown current
2.4W(typ)
2.1W(typ)
1.9W(typ)
1.1W(typ)
0.5%(max)
0.7µA(typ)
Features
n
n
n
n
n
Input mux control and two separate inputs per channel
Stereo headphone amplifier mode
“Click and pop” suppression circuitry
Thermal shutdown protection circuitry
Exposed-DAP TSSOP and TSSOP packaging available
Applications
n
Multimedia monitors
n
Portable and desktop computers
n
Portable audio systems
Typical Application
DS100993-31
*
Refer to the section Proper Selection of External Components, for a detailed discussion of C
B
size.
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer
®
is a registered trademark of National Semiconductor Corporation.
© 2000 National Semiconductor Corporation
DS100993
www.national.com
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