LM4895 Datasheet, PDF (1/15 Pages) National Semiconductor (TI) – 1 Watt Fully Differential Audio Power Amplifier With Shutdown Select and Fixed 6dB Gain

October 2002
LM4895
1 Watt Fully Differential Audio Power Amplifier With
Shutdown Select and Fixed 6dB Gain
General Description
The LM4895 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 watt of continuous average
power to an 8Ω load with less than 1% distortion (THD+N)
from a 5V_DC power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4895 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 LM4895 features a low-power consumption shutdown
mode. To facilitate this, Shutdown may be enabled by either
logic high or low depending on mode selection. Driving the
shutdown mode pin either high or low enables the shutdown
select pin to be driven in a likewise manner to enable Shut-
down. Additionally, the LM4895 features an internal thermal
shutdown protection mechanism.
The LM4895 contains advanced pop & click circuitry which
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
The LM4895 has an internally fixed gain of 6dB.
Key Specifications
j Improved PSRR at 217Hz
j Power Output at 5.0V & 1% THD
j Power Output at 3.3V & 1% THD
j Shutdown Current
80dB
1.0W(typ.)
400mW(typ.)
0.1µA(typ.)
Features
n Fully differential amplification
n Internal-gain-setting resistors
n Available in space-saving packages micro SMD, MSOP
and LLP
n Ultra low current shutdown mode
n Can drive capacitive loads up to 500 pF
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 2.2 - 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
n Shutdown high or low selectivity
Applications
n Mobile phones
n PDAs
n Portable electronic devices
Typical Application
20023201
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200232
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