LM48821 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Direct Coupled, Ultra Low Noise, 52mW Differential Input Stereo Headphone Amplifier with I2C Volume Control

June 2007
LM48821
Direct Coupled, Ultra Low Noise, 52mW Differential Input
Stereo Headphone Amplifier with I2C Volume Control
General Description
With its directly-coupled output technology, the LM48821 is a
variable gain audio power amplifier capable of delivering
52mW_RMS per channel into a 16Ω single-ended load with less
than 1% THD+N from a 3V power supply. The I²C volume
control has a range of –76dB to 18dB.
The LM48821's Tru-GND technology utilizes advanced
charge pump technology to generate the LM48821’s negative
supply voltage. This eliminates the need for output-coupling
capacitors typically used with single-ended loads.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM48821 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption is a primary re-
quirement.
The LM48821 incorporates selectable low-power consump-
tion shutdown and channel select modes.
The LM48821 contains advanced output transient suppres-
sion circuitry that eliminates noises which would otherwise
occur during turn-on and turn-off transitions.
Key Specifications
■ Improved PSRR at 217Hz
■ Stereo Output Power at V_DD = 3V,
R_L = 16Ω, THD+N = 1%
■ Mono Output Power at V_DD = 3V,
R_L = 16Ω, THD+N = 1%
■ Shutdown current
82dB (typ)
52mW (typ)
93mW (typ)
0.1μA (typ)
Features
■ ^{Ground referenced outputs}
■ ^{Differential Inputs}
■ ^{I2C Volume and mode controls}
■ ^{Available in space-saving micro SMD package}
■ ^{Ultra low current shutdown mode}
■ ^{Advanced output transient suppression circuitry}
eliminates noises during turn-on and turn-off transitions
■ ^{2.0V to 4.0V operation (PV}_DD ^{and SV}_DD⁾
■ ^{1.8 to 4.0V operation (I2CV}_DD⁾
■ ^{No output coupling capacitors, snubber networks,}
bootstrap capacitors, or gain-setting resistors required
Applications
■ ^{Notebook PCs}
■ ^{Desktop PCs}
■ ^{Mobile Phones}
■ ^PDAs
■ ^{Portable Electronic Devices}
■ ^{MP3 Players}
Boomer® is a registered trademark of National Semiconductor Corporation.
Tru-GND is a trademark of National Semiconductor Corporation.
© 2007 National Semiconductor Corporation 201842
www.national.com