NXP has announced a 3.6V loudspeaker driver that can deliver 3.4Wrms into an 8Ω speaker.
The voltage headroom required comes from an on-chip dc-dc converter with a 9.5V output.
Aimed at mobile phone use, it can deliver a lot of sound from small speakers in small enclosures.
As such, the Class-D amplifier has output current sensing which allows an on-die DSP to measure speaker resonance in real time and notch the output spectrum to prevent damage and distortion through transducer over-excursion.
Called the TFA9890, "it maximises acoustic output while ensuring diaphragm displacement and voice coil temperature do not exceed rated limits. This function is based on a generic box model that operates in all loudspeaker environments: free air, closed box or vented box," said the firm.
Audio has to be provided over I2S, and control settings over I2C.
The firm has yet to make the data sheet widely available.
Source:
http://www.electronicsweekly.com/Articles/2013/03/08/55722/speaker-driver-gets-big-sound-from-small-boxes.htm
