For smart phones, tablet PC / Multimedia Internet Device (MID) and portable media players and other mobile products, designers are faced with challenge to make small speakers provide louder and clearer audio, and meantime, minimize the impact on battery life.
Therefore, the world's leading high-performance and portable power supplier Fairchild Corporation (Fairchild Semiconductor) has developed step-down converter with integrated FAB1200 stereo Class-G ground-referenced headphone amplifier, headphone amplifiers with a stereo Class-G and FAB2200 audio subsystem of 1.2W Class-D mono speaker amplifier.
FAB1200 features charge bump which can generate negative power supply voltage and make the earphone output ground-centered with no capacitor in need, thus, to save two external capacitors. The device uses an integrated sensor buck regulator to directly connect the battery, and is based on the output signal level to adjust the supply voltage between two different levels, thereby to reduce the power consumption. This feature can reduce system costs and extend battery life effectively. Meantime, maintain high the high audio quality level.
The device adopts a 16-bump, 0.4mm pitch and 1.56mm x 1.56mm WLCSP package, providing excellent audio performance, which can achieve louder sound quality of audio headset for mobile phone handsets, tablet / MID, MP3 and portable media players .
FAB2200 combines a capacitor-free stereo Class-G headphone amplifier with a Class-D speaker amplifier audio subsystem. This solution uses a specialized integrated charge pump to generate multiple supply rails for providing the ground-centered Class-G headphone output. Compared to the programs of Class-AB design, new products can significantly reduce power consumption while providing high power supply rejection ratio.
Class-G headphone and Class-D speaker amplifier have louder and clearer audio and longer battery life.
Class-D amplifier without filter can be directly connected to a speaker, which can eliminate two external filter network, thereby reducing overall system cost. The device also has AGC (Automatic Gain Control) functions to limit the speaker's maximum output level to protect the speaker and prevent the introduction of distortion. It also limits rang dynamically as the battery voltage drops. The related integrated circuit is
MC14538BCP.
