The LM4990 is an audio power amplifier primarily designed for demanding applications in
mobile phones and other portable communication device applications. It is capable of delivering
1.25 watts of continuous average power to an 8Ω BTL load and 2 watts of continuous average power
(NGZ and DGQ only) to a 4Ω BTL load with less than 1% distortion (THD+N+N) from a
5VDC power supply.
Boomer audio power amplifiers were designed specifically to provide high quality output
power with a minimal amount of external components. The LM4990 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 LM4990 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 pin to be driven in a likewise manner to enable
The LM4990 contains advanced pop & click circuitry which eliminates noise which would
otherwise occur during turn-on and turn-off transitions.
The LM4990 is unity-gain stable and can be configured by external gain-setting resistors.
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