LM4906 Datasheet, PDF (1/15 Pages) National Semiconductor (TI) – 1W, Bypass-Capacitor-less Audio Amplifier with Internal Selectable Gain

May 2003
LM4906
1W, Bypass-Capacitor-less Audio Amplifier with Internal
Selectable Gain
General Description
The LM4906 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 1W of continuous average power to an 8Ω BTL
load with less than 1% distortion (THD+N) from a +5V power
supply.
The LM4906 is the first National Semiconductor Boomer
Power Amplifier that does not require an external PSRR
bypass capacitor. The LM4906 also has an internal select-
able gain of either 6dB or 12dB. In addition, no output
coupling capacitors or bootstrap capacitors are required
which makes the LM4906 ideally suited for cell phone and
other low voltage portable applications.
The LM4906 contains advanced pop and click circuitry that
eliminates noise, which would otherwise occur during
turn-on and turn-off transitions.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4906 features a low -power
consumption shutdown mode (the part is enabled by pulling
the SD pin high). Additionally, the LM4906 features an inter-
nal thermal shutdown protection mechanism.
Key Specifications
j Improved PSRR at 217Hz for +3V
71dB
j Power Output at +5V, THD+N = 1%, 8Ω 1.0W (typ)
j Power Output at +3V, THD+N = 1%, 8Ω 390mW (typ)
j Total shutdown power supply current
0.1µA (typ)
Features
n Selectable gain of 6dB (2V/V) or 12dB (4V/V)
n No output or PSRR bypass capacitors required
n Improved “Click and Pop” suppression circuitry
n Very fast turn on time: 5ms (typ)
n Minimum external components
n 2.6 - 5.5V operation
n BTL output can drive capacitive loads
n Ultra low current shutdown mode (SD Low)
Applications
n Portable computers
n Desktop computers
n Multimedia monitors
Typical Application
200571B9
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2003 National Semiconductor Corporation DS200571
www.national.com