National unveils PowerWise stereo headphone amplifier
Most of us who own a pair of headphones never really think too much about what is inside, as long as it does its job fairly well. Some of us are more demanding than the others though, and would only pick up a pair that comes with exchangeable eartips, noise-cancellation as well as a host of other features such as integrated Dolby decoding for superior audio, but I’m fairly sure that for Joe Average, a standard pair will do as there comes a point when the law of diminishing returns kicks in, making all that extra money spent just to extract a bit more performance totally not worth it. National Semiconductor has a brand new pair of stereo headphones amplifier for the masses – the PowerWise which sips only 0.9 mA (typical) of quiescent current in order to double the audio playback time of smart phones, full-featured mobile phones and portable music players.
Known as the LM48824 Class G architecture, this is able to significantly increase audio (MP3, mobile TV, etc.) playback time courtesy of its adaptive power supply approach which makes allowance for extremely low supply rails, hence doubling the power-efficiency compared to a standard Class AB headphone amplifier. Not only that, the LM48824’s output noise created by ground mismatches has also improved through the use of common-mode sensing which corrects for differences between the amplifier ground and the headphone return terminal.
For those who are interested, the LM48824 will come an extremely tiny, 16-bump, 1.7 mm by 1.7 mm, 0.4 mm-pitch micro SMD package. You will be able to find National’s ground-referenced architecture that in turn saves space while minimizing system cost by eliminating the need for bulky and expensive DC blocking capacitors. Other features include a 32-step I2C compatible volume control with mute and delivers 37 mW per channel into a 16-Ohm load with less than one percent total harmonic distortion plus noise (THD+N) at 3.6V. Industry watchers will be able to pick up the the LM48824 at $1.06 a pop in 1,000-unit quantities.