1FEATURES

2• Available in Space-Saving WSON and SOIC

Packages

• Ultra Low Current Shutdown Mode

• Can Drive Capacitive Loads up to 500pF

• Improved Click and Pop Circuitry Reduces

Noises During Turn-On and Turn-Off

Transitions

• 2.2 - 5.5V Operation

• No Output Coupling Capacitors, Snubber

Networks, Bootstrap Capacitors or Gain-

Setting Resistors Required

• Unity-Gain Stable

APPLICATIONS

• Wireless and Cellular Handsets

• PDAs

• Portable Computers

• Desktop Computers

KEY SPECIFICATIONS

• Improved PSRR at 217kHz and 1kHz: 64 dB

(typ)

• PO at VDD = 5.0V, 10% THD, 1kHz

– LM4991LD (only), 3Ω, 4Ω: 3W (typ), 2.5 W

(typ)

– All packages, 8Ω load: 1.5 W (typ)

• Shutdown current: 0.1μA (typ)

DESCRIPTION

The LM4991 is a mono bridged audio power amplifier

capable of delivering 3W of continuous average

power into a 3Ω load with less than 10% THD when

powered by a 5V power supply (see Note below). To

conserve power in portable applications, the

LM4991's micropower shutdown mode (ISD = 0.1μA,

typ) is activated when VDD is applied to the

SHUTDOWN pin.

Boomer audio power amplifiers are designed

specifically to provide high power, high fidelity audio output. They require few external components and

operate on low supply voltages from 2.2V to 5.5V.

Since the LM4991 does not require output coupling

capacitors, bootstrap capacitors, or snubber

networks, it is ideally suited for low-power portable

systems that require minimum volume and weight.

Additional LM4991 features include thermal shutdown

protection, unity-gain stability, and external gain set.

Note: An LM4991LD that has been properly mounted

to a circuit board will deliver 3W into 3Ω (at 10% THD). The other package options for the LM4991 will

deliver 1.5W into 8Ω (at 10% THD). See the

Application Information sections for further

information concerning the LM4991LD and

LM4991M.