LM4910 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Output Capacitor-less Stereo 35mW Headphone Amplifier

February 2003
LM4910
Output Capacitor-less Stereo 35mW Headphone
Amplifier
General Description
The LM4910 is an audio power amplifier primarily designed
for headphone applications in portable device applications. It
is capable of delivering 35mW of continuous average power
to a 32Ω load with less than 1% distortion (THD+N) from a
3.3V_DC power supply.
The LM4910 utilizes a new circuit topology that eliminates
output coupling capacitors and half-supply bypass capaci-
tors (patent pending). The LM4910 contains advanced pop &
click circuitry which eliminates noises caused by transients
that would otherwise occur during turn-on and turn-off.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. Since the LM4910 does not require
any output coupling capacitors, half-supply bypass capaci-
tors, or bootstrap capacitors, it is ideally suited for low-power
portable applications where minimal space and power con-
sumption are primary requirements.
The LM4910 features a low-power consumption shutdown
mode, activated by driving the shutdown pin with logic low.
Additionally, the LM4910 features an internal thermal shut-
down protection mechanism. The LM4910 is also unity-gain
stable and can be configured by external gain-setting resis-
tors.
Key Specifications
n PSRR at f = 217Hz
65dB (typ)
n Power Output at V_DD = 3.3V, R_L = 32Ω, and THD ≤
1%
35mW (typ)
n Shutdown Current
0.1µA (typ)
Features
n Eliminates headphone amplifier output coupling
capacitors (patent pending)
n Eliminates half-supply bypass capacitor (patent pending)
n Advanced pop & click circuitry eliminates noises during
turn-on and turn-off
n Ultra-low current shutdown mode
n Unity-gain stable
n 2.2V - 5.5V operation
n Available in space-saving MSOP, LLP, and SOIC
packages
Applications
n Mobile Phones
n PDAs
n Portable eletronics devices
n Portable MP3 players
Typical Application
20030565
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200305
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