|
LM49370_08 Datasheet, PDF (1/100 Pages) National Semiconductor (TI) – Audio Sub-System with an Ultra Low EMI, Spread Spectrum, Class D Loudspeaker Amplifier, a Dual-Mode | |||
|
February 11, 2008
LM49370
Audio Sub-System with an Ultra Low EMI, Spread
Spectrum, Class D Loudspeaker Amplifier, a Dual-Mode
Stereo Headphone Amplifier, and a Dedicated PCM
Interface for Bluetooth Transceivers
1.0 General Description
The LM49370 is an integrated audio subsystem that supports
both analog and digital audio functions. The LM49370 in-
cludes a high quality stereo DAC, a mono ADC, a stereo
headphone amplifier, which supports output cap-less (OCL)
or AC-coupled (SE) modes of operation, a mono earpiece
amplifier, and an ultra-low EMI spread spectrum Class D
loudspeaker amplifier. It is designed for demanding applica-
tions in mobile phones and other portable devices.
The LM49370 features a bi-directional I2S interface and a bi-
directional PCM interface for full range audio on either inter-
face. The LM49370 utilizes an I2C or SPI compatible interface
for control. The stereo DAC path features an SNR of 85 dB
with an 18-bit 48 kHz input. In SE mode the headphone am-
plifier delivers at least 33 mWRMS to a 32⦠single-ended
stereo load with less than 1% distortion (THD+N) when
A_VDD = 3.3V. The mono earpiece amplifier delivers at least
115mWRMS to a 32⦠bridged-tied load with less than 1% dis-
tortion (THD+N) when A_VDD = 3.3V. The mono speaker
amplifier delivers up to 490mW into an 8⦠load with less than
1% distortion when LS_VDD = 3.3V and up to 1.2W when
LS_VDD = 5.0V.
The LM49370 employs advanced techniques to reduce pow-
er consumption, to reduce controller overhead, to speed de-
velopment time, and to eliminate click and pop. Boomer audio
power amplifiers were designed specifically to provide high
quality output power with a minimal amount of external com-
ponents. It is therefore ideally suited for mobile phone and
other low voltage applications where minimal power con-
sumption, PCB area and cost are primary requirements.
2.0 Applications
â Smart phones
â Mobile Phones and Multimedia Terminals
â PDAs, Internet Appliances and Portable Gaming
â Portable DVD/CD/AAC/MP3 Players
â Digital Cameras/Camcorders
3.0 Key Specifications
â PHP (AC-COUP) (A_VDD = 3.3V, 32â¦, 1% THD)
â PHP (OCL) (A_VDD = 3.3V, 32â¦, 1% THD)
â PLS ( LS_VDD = 5V, 8â¦, 1% THD)
â PLS (LS_VDD = 4.2V, 8â¦, 1% THD)
â PLS (LS_VDD = 3.3V, 8â¦, 1% THD)
â Shutdown Current
â PSRRLS (217 Hz, LS_VDD = 3.3V)
33 mW
31 mW
1.2 W
900 mW
490 mW
0.8 µA
70 dB
â SNRLS (AUX IN to Loudspeaker)
â SNRDAC (Stereo DAC to AUXOUT)
â SNRADC (Mono ADC from Cell Phone In)
â SNRHP (Aux In to Headphones)
90 dB (typ)
85 dB (typ)
90 dB (typ)
98 dB (typ)
4.0 Features
â Spread Spectrum Class D architecture reduces EMI
â Mono Class D 8⦠amplifier, 490 mW at 3.3V
â OCL or AC-coupled headphone operation
â 33mW stereo headphone amplifier at 3.3V
â 115 mW earpiece amplifier at 3.3V
â 18-bit stereo DAC
â 16-bit mono ADC
â 8 kHz to 192 kHz stereo audio playback
â 8 kHz to 48 kHz mono recording
â Bidirectional I2S compatible audio interface
â Bidirectional PCM compatible audio interface for
Bluetooth transceivers
â I2S-PCM Bridge with sample rate conversion
â Sigma-Delta PLL for operation from any clock at any
sample rate
â Digital 3D Stereo Enhancement
â FIR filter programmability for simple tone control
â Low power clock network operation if a 12 MHz or 13 MHz
system clock is available
â Read/write I2C or SPI compatible control interface
â Automatic headphone & microphone detection
â Support for internal and external microphones
â Automatic gain control for microphone input
â Differential audio I/O for external cellphone module
â Mono differential auxiliary output
â Stereo auxiliary inputs
â Differential microphone input for internal microphone
â Flexible audio routing from input to output
â 32 Step volume control for mixers in 1.5 dB steps
â 16 Step volume control for microphone in 2 dB steps
â Programmable sidetone attenuation in 3 dB steps
â Two configurable GPIO ports
â Multi-function IRQ output
â Micro-power shutdown mode
â Available in the 4 x 4 mm 49 bump micro SMDxt package
Boomer® is a registered trademark of National Semiconductor Corporation.
© 2008 National Semiconductor Corporation 201917
www.national.com
|
▷ |