LM48822 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Ground-Referenced, Ultra High PSRR, Ultra Low Noise, 35mW/Channel Stereo Headphone Amplifier with CommonMode Sense, and I2C Volume Control

July 10, 2008
LM48822
Ground-Referenced, Ultra High PSRR, Ultra Low Noise,
35mW/Channel Stereo Headphone Amplifier with Common
Mode Sense, and I²C Volume Control
General Description
The LM48822 is a single supply, ground-referenced stereo
headphone amplifier designed for portable devices, such as
cell phones, where board space is at a premium. The
LM48822 features National’s ground-referenced architecture,
which eliminates the large DC blocking capacitor required by
traditional headphone amplifiers, saving board space and
minimizing system cost.
The LM48822 features common-mode sensing that corrects
for any differences between the amplifier ground and the po-
tential at the headphone return terminal, minimizing noise
created by any ground mismatches.
The LM48822 delivers 35mW/channel into a 16Ω load with
<1% THD+N with a 3.6V supply. High power supply rejection
ratio (PSRR), of 110dB at 217Hz, allows the device to operate
in noisy environments without additional power supply condi-
tioning. Flexible power supply requirements allow operation
from 2.4V to 5.5V. The LM48822 has a differential inputs for
improved noise rejection. High output impedance in Shut-
down mode, combined with a charge pump-only mode allows
the LM48822's outputs to be driven by an external source
without degrading the source signal. Additionally, the
LM48822 features a 64-step I²C volume control and mute
function. The low power Shutdown mode reduces supply cur-
rent consumption to 0.06µA.
Superior click and pop suppression eliminates audible tran-
sients on power-up/down and during shutdown. The
LM48822 is available in an ultra-small 16-bump micro SMD
package (2mmx2mm)
Key Specifications
■ Output Power/channel at V_DD = 3.6V
R_L = 16Ω, THD+N ≤ 1%
■ Output Power/channel at V_DD = 3.6V
R_L = 32Ω, THD+N ≤ 1%
■ Quiescent Power Supply Current
at 3.6V
■ PSRR at 217Hz
■ Shutdown current
35mW (typ)
40mW (typ)
3.5mA (typ)
110dB (typ)
0.06μA (typ)
Features
■ ^{Ground Referenced Outputs – Eliminates Output Coupling}
Capacitors
■ ^{Common-Mode Sense}
■ ^{Ultra-High PSRR}
■ ^{I2C Volume and Mode Control}
■ ^{High Output Impedance in Shutdown}
■ ^{Differential Inputs}
■ ^{Advanced Click-and-Pop Suppression}
■ ^{Low Supply Current}
■ ^{Minimum external components}
■ ^{Micro-power shutdown}
■ ^{Available in space-saving 16-bump µSMD package}
Applications
■ ^{Mobile Phones}
■ ^PDAs
■ ^{Notebook PCs}
■ ^{Portable Electronic Devices}
■ ^{MP3 Players}
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2008 National Semiconductor Corporation 300610
www.national.com