LM49155 Uplink Noise Suppression & Downlink SNR Enhancement Analog Audio Subsystem

Features
Noise cancellation for uplink and downlink without DSP-type artifacts, distortions or delays
Adapting AGC on ambient noise level & downlink signal strength for earpiece
Downlink adjustable noise-reducing high pass filter
E 2S Class D Amplifier with ALC
Ground Referenced Headphone Outputs with Advanced Click Pop Suppression
Micro-power shutdown

Description

The LM49155 is a fully integrated audio subsystem designed for portable handheld applications such as cellular phones. The LM49155 combines a Noise Suppression microphone amplifier, a 1.35W mono class D amplifier with ALC, class AB earpiece driver with AGC, a high efficiency, stereo, ground referenced headphone amplifier with click pop suppression and I 2C modes select and volume control.

The LM49155 features analog fully differential input, and differential output microphone amplifier designed to reduce background acoustic noise, while delivering superb speech clarity in voice communication applications. Downlink SNR enhancement with an advanced acoustic AGC technology to adjust output levels.

The LM49155 speaker amplifier features National’s unique output limiter that provides both a no-clip feature and speaker protection. The E 2S class D amplifier features a patented, ultra low EMI PWM architecture that significantly reduces RF emissions while preserving audio quality and efficiency. The headphone drivers feature National’s ground referenced architecture that creates a ground-referenced output from a single, low-voltage supply.


Applications
Mobile Phones
Portable Electronic Devices

download lm49155 datasheet

Mono Class D Audio Codec Subsytem with Ground Referenced Headphone Amplifiers

Features

Ultra efficient, spread spectrum Class D loudspeaker amplifier that operates at 93% efficiency
Low voltage, true ground headphone amplifier operation
High performance 103dB SNR stereo DAC
High performance 97dB SNR stereo ADC
Up to 96kHz stereo audio playback
Up to 48kHz stereo recording
Dual bidirectional I 2S or PCM compatible audio interfaces
Read/write I 2C compatible control interface
Flexible digital mixer with sample rate conversion
Sigma-delta PLL clock network that supports system clocks up to 50MHz including 13MHz, 19.2MHz, and 26MHz
Dual stereo 5 band parametric equalizers
Cascadable DSP effects that allow stereo 10 band parametric equalization
ALC/Limiter/Compressor on both DAC and ADC paths
Dedicated Earpiece Speaker Amplifier
Stereo auxiliary inputs and mono differential input
Differential microphone input with single-ended option
Automatic level control for digital audio inputs, mono differential input, microphone input, and stereo auxiliary inputs
Flexible audio routing from input to output
16 Step volume control for microphone with 2dB steps
32 Step volume control for auxiliary inputs in 1.5dB steps
4 Step volume control for class D loudspeaker amplifier
8 Step volume control for headphone amplifier
Micro-power shutdown mode
Available in the 3.3 x 3.3 mm 36 bump micro SMD package

Description
The LM49352 is a high performance mixed signal audio subsystem. The LM49352 includes a high quality stereo DAC, a high quality stereo ADC, a stereo headphone amplifier, which supports True Ground operation, a low EMI Class D loudspeaker amplifier, and an earpiece speaker amplifier. It combines advanced audio processing, conversion, mixing, and amplification in the smallest possible footprint while extending the battery life of feature rich portable devices.
The LM49352 features dual bi-directional I 2S or PCM audio interfaces and an I 2C compatible interface for control. The stereo DAC path features an SNR of 103dB with 24-bit 48 kHz input. The headphone amplifier delivers 65mWRMS (typ) to a 32Ω single-ended stereo load with less than 1% distortion (THD+N) when HP_VDD = 2.8V. The loudspeaker amplifier delivers up to 970mW into an 8Ω load with less than 1% distortion when LS_VDD = 4.2V.
The LM49352 employs advanced techniques to extend battery life, to reduce controller overhead, to speed development time, and to eliminate click and pop artifacts. Boomer audio power amplifiers are designed specifically for mobile devices and require minimal PCB area and external components.

Applications
Smart Phones
Mobile Phones and VOIP Phones
Portable GPS Navigator and Portable Gaming Devices
Portable DVD/CD/AAC/MP3/MP4 Players
Digital Cameras/Camcorders


download datasheet from http://www.national.com/