LM4941 Datasheet, PDF (1/13 Pages) National Semiconductor (TI) – 1.25 Watt Fully Differential Audio Power Amplifier With RF Suppression and Shutdown

June 2006
LM4941
1.25 Watt Fully Differential Audio Power Amplifier With
RF Suppression and Shutdown
General Description
The LM4941 is a fully differential audio power amplifier
primarily designed for demanding applications in mobile
phones and other portable communication device applica-
tions. It is capable of delivering 1.25 watts of continuous
average power to a 8Ω load with less than 1% distortion
(THD+N) from a 5V_DC power supply. The LM4941 does not
require output coupling capacitors or bootstrap capacitors,
and therefore is ideally suited for mobile phone and other low
voltage applications where minimal power consumption is a
primary requirement.
The LM4941 also features proprietary internal circuitry that
suppresses the coupling of RF signals into the chip. This is
important because certain types of RF signals (such as
GSM) can couple into audio amplifiers in such a way that
part of the signal is heard through the speaker. The RF
suppression circuitry in the LM4941 makes it well-suited for
portable applications in which strong RF signals generated
by an antenna from or a cellular phone or other portable
electronic device may couple audibly into the amplifier.
Other features include a low-power consumption shutdown
mode, internal thermal shutdown protection, and advanced
pop & click circuitry.
Key Specifications
j Improved PSRR at 217Hz
j Power Output at 5.0V @ 1% THD (8Ω)
j Power Output at 3.3V @ 1% THD
j Shutdown Current
95dB (typ)
1.25W (typ)
550mW (typ)
0.1µA (typ)
Features
n Improved RF suppression, by up to 20dB over previous
designs in selected applications
n Fully differential amplification
n Available in space-saving micro SMD package
n Ultra low current shutdown mode
n Can drive capacitive loads up to 100pF
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 2.4 - 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
Applications
n Mobile phones
n PDAs
n Portable electronic devices
Typical Application
20170303
FIGURE 1. Typical Audio Amplifier Application Circuit
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