San FranciscoNational Semiconductor Corp. has expanded its line of low-power Boomer Class D audio subsystems with two devicesthe LM49352 mixed-signal audio subsystem and LM49151 analog subsystemaimed at simplifying portable product design.
The LM49352 and LM49151 are targeted at smart phones, full-featured phones, portable gaming devices and portable GPS devices. The LM49352 mixed-signal audio subsystem integrates audio codec functionality with ground-referenced headphone amplifiers, earpiece driver, Class D loudspeaker and audio digital signal processor (DSP) in one miniature 3.3 mm by 3.3 mm package. The loudspeaker delivers high efficiency (93 percent at 970 mW from a 4.2V supply), while the headphone amplifier offers low-power (18 mW) MP3 playback to extend battery life.
The LM49151 analog subsystem integrates an earpiece driver, Class D loudspeaker, ground-referenced headphone amplifiers and automatic level control (ALC) in an ultra-small 2.2 mm by 2.6 mm package. According to National, the LM49151 offers the lowest power in its class, consuming 7.3 mA of quiescent current at 3.3V for the loudspeaker and headphone. The subsystem's ALC feature provides handset manufacturers with a variety of options to control audio distortion levels and prevent speaker damage.
National Semiconductor, www.national.com