Low-Cost, Mono/Stereo,
1 W Differential Audio Power Amplifiers
■ General Description
The LM4890 is an audio power amplifier primarily designed for demanding applications in
mobile phones and other portable 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.
Boomer audio power amplifiers were designed specifically to provide high quality output
power with a minimal amount of external components. The LM4890 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 LM4890 features a low-power consumption shutdown mode, which is achieved by
driving the shutdown pin with logic low. Additionally, the LM4890 features an internal thermal
shutdown protection mechanism.
The LM4890 contains advanced pop & click circuitry which eliminates noises which would
otherwise occur during turn-on and turn-off transitions.
The LM4890 is unity-gain stable and can be configured by external gain-setting resistors.
■ Key Specifications
l  PSRR at 217Hz, VDD = 5V (Fig. 1) 62dB(typ.)
l  Power Output at 5.0V & 1% THD 1W(typ.)
l  Power Output at 3.3V & 1% THD 400mW(typ.)
l  Shutdown Current 0.1μA(typ.)
■ Features
l  Available in space-saving packages: micro SMD, MSOP,SOIC, and LLP
l  Ultra low current shutdown mode
l  BTL output can drive capacitive loads
l  Improved pop & click circuitry eliminates noises during turn-on and turn-off transitions
l  2.2 - 5.5V operation
l  No output coupling capacitors, snubber networks or bootstrap capacitors required
l  Thermal shutdown protection
l  Unity-gain stable
l  External gain configuration capability
■ Applications
l  Mobile Phones
l  PDAs
l  Portable electronic devices