LM48824 Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – Class G Headphone Amplifier with I2C Volume Control

LM48824
August 31, 2009
Class G Headphone Amplifier with I²C Volume Control
General Description
Key Specifications
The LM48824 is a Class G, ground-referenced stereo head-
phone amplifier designed for portable devices. The LM48824
■ Quiescent Power Supply Current at 3.6V
0.9mA (typ)
features National’s ground-referenced architecture, which _{■ Output Power/channel at VDD = 3.6V}
eliminates the large DC blocking capacitors required by tra-
ditional headphone amplifiers, saving board space and mini-
R_L = 16Ω, THD+N ≤ 1%
mizing system cost.
■ Output Power/channel at V_DD = 3.6V
The LM48824 takes advantage of National’s patent-pending
R_L = 32Ω, THD+N ≤ 1%
Class G architecture offering power savings compared to a
traditional Class AB headphone amplifier. Additionally, output
■ PSRR at 217Hz
37mW (typ)
29mW (typ)
100dB (typ)
noise is improved by common-mode sensing that corrects for ■ Shutdown current
any differences between the amplifier ground and the poten-
2.5μA (typ)
tial at the headphone return terminal, minimizing noise creat-
ed by any ground mismatches.
A high output impedance mode allows the LM48824's outputs
to be driven by an external source without degrading the sig-
nal. Other features include flexible power supply require-
Features
■ ^{Class G Power Savings}
■ ^{Ground Referenced Headphone Outputs – Eliminates}
Output Coupling Capacitors
ments, differential inputs for improved noise rejection, a low
power (2.5μA) shutdown mode, and a 32-step I²C volume
control with mute function.
The LM48824's superior click and pop suppression eliminates
audible transients on power-up/down and during shutdown.
The LM48824 is available in an ultra-small 16-bump, 0.4mm
■ ^{Common-Mode Sense}
■ ^{I2C Volume and Mode Control}
■ ^{High Output Impedance in Shutdown}
■ ^{Differential Inputs}
■ ^{Advanced Click-and-Pop Suppression}
pitch micro SMD package (1.69mm x 1.69mm)
■ ^{Low Supply Current}
■ ^{Low THD mode option}
Applications
■ ^{Mobile Phones, PDAs, MP3 Players}
■ ^{Portable Electronic Devices, Notebook PCs}
Simplified Block Diagram
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