LM48820 Datasheet, PDF (1/16 Pages) National Semiconductor (TI) – Ground-Referenced, Ultra Low Noise, Fixed Gain, 95mW Stereo Headphone Amplifier

June 2007
LM48820
Ground-Referenced, Ultra Low Noise, Fixed Gain, 95mW
Stereo Headphone Amplifier
General Description
The LM48820 is a ground referenced, fixed-gain audio power
amplifier capable of delivering 95mW of continuous average
power into a 16Ω single-ended load, with less than 1% THD
+N from a 3V power supply.
The LM48820 features a new circuit technology that utilizes
a charge pump to generate a negative reference voltage. This
allows the outputs to be biased about ground, thereby elimi-
nating output-coupling capacitors typically used with normal
single-ended loads.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal number of
external components. The LM48820 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other portable applica-
tions.
The LM48820 features a low-power consumption shutdown
mode selectable for each channel and a soft start function that
reduces start-up current transients. Additionally, the
LM48820 features an internal thermal shutdown protection
mechanism.
The LM48820 contains advanced pop & click circuitry that
eliminates noises which would otherwise occur during turn-on
and turn-off transitions.
The LM48820 has an internal fixed gain of 1.5V/V.
Key Specifications
■ Improved PSRR at 217Hz
■ Power Output at V_DD = 3V,
R_L = 16Ω, THD+N = 1%
■ Shutdown Current
■ Internal Fixed Gain
■ Wide Operating Voltage Range
80dB (typ)
95mW (typ)
0.05µA (typ)
1.5V/V (typ)
1.6V to 4.5V
Features
■ ^{Available in space saving 0.4mm pitch micro SMD}
package
■ ^{Fixed Logic Levels}
■ ^{Ground referenced outputs}
■ ^{High PSRR}
■ ^{Ultra low current shutdown mode}
■ ^{Improved pop & click circuitry eliminates noises during}
turn-on and turn-off transitions
■ ^{No output coupling capacitors, snubber networks,}
bootstrap capacitors, or gain-setting resistors required
■ ^{Shutdown either channel independently}
■ ^{Soft start feature reduces start up transient current}
Applications
■ ^{Mobile Phones}
■ ^{MP3 Players}
■ ^PDAs
■ ^{Portable electronic devices}
■ ^{Notebook PCs}
Boomer^® is a registered trademark of National Semiconductor Corporation.
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