NATIONAL Semiconductor Corporation, represented by Arrow Electronics Australia Pty Ltd , has released the Boomer LM4844 audio subsystem to simplify development of superior full-bandwidth stereo and 3D sound in mobile phones and other battery-powered devices. Boomer audio power amplifiers provide high-quality output power with a minimal number of external components.
“As consumers demand sophisticated features such as music playback, mobile phone manufacturers require a much higher-quality audio solution than previous phones that just carried voice content,” said vice president of National’s Audio Products Group, Mike Polacek.
“Boomer audio subsystems with output capacitor-less technology, such as the LM4844, allow designers to easily implement high-quality, feature-rich audio in their phones with a minimum amount of design work and board space.”
The LM4844 integrates 1.2W stereo speaker amplifiers and headphone drivers, volume control, mixing, power management features and National’s 3D sound enhancement.
Ten pre-programmed output modes combine these features into one simple-to-use, 2.5mm by 3mm micro SMD package.
The LM4844’s output capacitor-less (OCL) headphone topology eliminates the need for external capacitors at the headphone outputs, saving board space.
The OCL headphone topology also improves low frequency response and reduces the ‘pop and click’ noise of the headphone amplifier.
The subsystem further reduces pop and click noise from the headphone and speaker outputs through National’s suppression circuitry.
Operating on a 3.3V supply, National’s LM4844 integrated stereo speaker drivers deliver 495mW of output power per channel into an 8Ω load and the stereo headphone drivers deliver up 33mW into a 32Ω load.
The subsystem is controlled through an I2 C compatible interface that allows designers to use independent left-, right- and mono-volume controls.
The LM4844’s 3D enhancement improves stereo channel separation when the left and right speakers are too close together and solves problems that would otherwise arise from system size constraints or equipment limitations.
In addition, the LM4844 routes and mixes the stereo and mono inputs into 10 distinct output modes, which gives designers flexibility to route and mix audio signals to either the stereo speakers or stereo headphones. In addition, it features low shutdown current of 0.1µA typical.