LM4892 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – 1 Watt Audio Power Amplifier with Headphone Sense

October 2002
LM4892
1 Watt Audio Power Amplifier with Headphone Sense
General Description
The LM4892 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 1 watt of continuous average power to an 8Ω BTL
load with less than 1% distortion (THD+N) from a 5V_DC
power supply. Switching between bridged speaker mode and
headphone (single-ended) mode is accomplished using the
headphone sense pin.
Boomer audio power amplifiers are designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4892 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 LM4892 features a low-power consumption shutdown
mode, which is achieved by driving the shutdown pin with
logic low. Additionally, the LM4892 features an internal ther-
mal shutdown protection mechanism.
The LM4892 contains advanced pop & click circuitry which
eliminates noise which would otherwise occur during turn-on
and turn-off transitions.
The LM4892 is unity-gain stable and can be configured by
external gain-setting resistors.
Key Specifications
j PSRR at 217Hz, V_DD = 5V, 8Ω Load
j Power Output at 5.0V & 1% THD
j Power Output at 3.3V & 1% THD
j Shutdown Current
62dB (typ)
1.0W (typ)
400mW (typ)
0.1µA (typ)
Features
n Available in space-saving packages: LLP, micro SMD,
MSOP, and SOIC
n Ultra low current shutdown mode
n BTL output can drive capacitive loads up to 500pF
n Improved pop & click circuitry eliminates noise 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 Thermal shutdown protection
n Unity-gain stable
n External gain configuration capability
n Headphone amplifier mode
Applications
n Mobile Phones
n PDAs
n Portable electronic devices
Typical Application
20012701
FIGURE 1. Typical Audio Amplifier Application Circuit (Pin #’s apply to M & MM packages)
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation DS200127
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