Date: 06/04/2009

Multifunction Audio IC with DSP, amplifier, driver, ADC, and DAC for smart phones

National Semiconductor has added two new devices to its family of low-power Boomer Class D audio subsystems. The LM49352 mixed-signal audio subsystem and LM49151 analog subsystem are targeted at smart phones and such high-end hand-held portables.

The LM49352 integrates audio codec functionality with ground-referenced headphone amplifiers, earpiece driver, Class D loudspeaker and audio digital signal processor (DSP) in one miniature 3.3mm by 3.3mm package. The loudspeaker delivers ultra-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.
LM49352 features a dual bi-directional I2S interface and PCM audio bridge to enable easy interface to peripherals such as Bluetooth modules, as well as an I2C compatible interface for programming different gains and modes.

The LM49352's stereo ADC provides a signal-to-noise ratio (SNR) of 97 dB with a 24-bit, 48 kHz signal and the DAC provides an SNR of 103 dB with a 24-bit, 48 kHz signal. The loudspeaker amplifier delivers up to 970 mW to an 8-Ohm load with less than one percent harmonic distortion plus noise (THD+N) at 4.2V.

The LM49352's digital signal processing includes dedicated effects circuits for both the DACs and ADCs. These circuits include volume control, ALC with compression and limiting, and 5-band equalization (EQ) for quality audio processing. The ADC also is equipped with a flexible wind noise filter that can operate in voice or high fidelity recording mode.

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.

The LM49151 consumes 7.3 mA of quiescent current at 3.3V for the loudspeaker and headphone, which is very low in comparison to other similar devices in the industry. The subsystem's ALC feature provides handset manufacturers with a variety of options to control audio distortion levels and prevent speaker damage.

Package: Micro SMD
Availability: Now

Price: LM49352: Each $7.55 for 1K units
LM49151: Each $1.60 for 1K units