LM4915 Datasheet, PDF (1/11 Pages) National Semiconductor (TI) – Pseudo-Differential Mono Headphone Amplifier with Fixed 6dB Gain

May 2003
LM4915
Pseudo-Differential Mono Headphone Amplifier with
Fixed 6dB Gain
General Description
The LM4915 is a pseudo-differential audio power amplifier
primarily designed for demanding applications in mobile
phones and other portable audio device applications with
mono headphones. It is capable of delivering 90 miliwatts of
continuous average power to a 32Ω BTL load with less than
1% distortion (THD+N) from a 3V_DC power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4915 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 LM4915 features a low-power consumption shutdown
mode. To facilitate this, Shutdown may be enabled by driving
the shutdown pin low. Additionally, the LM4915 features an
internal thermal shutdown protection mechanism.
The LM4915 contains advanced pop & click circuitry which
virtually eliminates noises which would otherwise occur dur-
ing turn-on and turn-off transitions.
The LM4915 has an internally fixed gain of 6dB.
Key Specifications
n Improved PSRR at 217Hz and 1kHz
75dB (typ)
n Power Output at 5.0V & 1% THD into 32Ω 280mW (typ)
n Power Output at 3.0V & 1% THD into 32Ω 90mW (typ)
n Output Noise, A-weighted
20µV (typ)
Features
n Pseudo-differential amplification
n Internal gain-setting resistors
n Available in space-saving LLP package
n Ultra low current shutdown mode
n Can drive capacitive loads up to 500pF
n Improved pop & click circuitry virtually eliminates noises
during turn-on and turn-off transitions
n 2.2 - 5.5V operation
n No output coupling capacitors, snubber networks,
bootstrap capacitors or gain-setting resistors required
n Ultra low noise
Applications
n Mobile phones
n PDAs
n Portable electronics devices
Typical Application
200482B4
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200482
www.national.com