LM4931_06 Datasheet, PDF (1/48 Pages) National Semiconductor (TI) – Audio Subsystem with Mono High Efficiency Loudsperker and Stereo Headphone Amplifiers

July 2006
LM4931
Audio Subsystem with Mono High Efficiency
Loudspeaker and Stereo Headphone Amplifiers
General Description
The LM4931 is an integrated audio subsystem that supports
voice and digital audio functions. The LM4931 includes a
high quality stereo DAC, voice band codec, a stereo head-
phone amplifier and a high-power high efficiency mono
speaker amplifier. It is primarily designed for demanding
applications in mobile phones and other portable devices.
The LM4931 features an I²S serial interface for full range
audio, a 16-bit PCM bi-directional serial interface for the
voice band codec and an I²C/SPI compatible interface for
control. The full range music path features an SNR of 86dB
with an 18-bit 48kHz input. The headphone amplifier delivers
at least 26mW_RMS to a 32Ω single-ended stereo load with
less than 1% distortion (THD+N) when AV_DD = 3.3V_DC. The
mono speaker amplifier delivers up to 570mW_RMS into an 8Ω
load with less than 1% distortion when AV_DD = 3.3V_DC.
The LM4931 employs advanced techniques to reduce power
consumption, to reduce controller overhead, and to eliminate
click and pop. Boomer audio power amplifiers were de-
signed specifically to provide high quality output power with
a minimal amount of external components. It is therefore
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption, PCB area, and
cost are primary requirements.
Key Specifications
j P_{LS OUT} at AV_DD = 5V, 8Ω
1% THD+N
1.1W (typ)
j P_{LS OUT} at AV_DD = 3.3V, 8Ω
1% THD+N
570mW (typ)
j P_{H/P OUT} at AV_DD = 5V & AV_DD = 3.3V, 32Ω
1% THD+N
26mW (typ)
j Supply voltage range
DV_DD
AV_DD (Note 8)
j Shutdown current
2.7V to 4.0V
2.7V to 5.0V
1.1µA (typ)
j PSRR at 217Hz, AV_DD = 3V
j SNR (Voice Codec)
62dB (typ)
75dB (typ)
j SNR (Audio DAC)
86dB (typ)
Features
n 18-bit 44.1kHz or 48kHz stereo DAC
n 16-bit 8kHz , 12kHz , 16kHz, or 24kHz voice-band
codec
n PLL for operation from common system clocks
n Either I²C or SPI compatible serial interface
n I²S digital audio data serial interface
n PCM voice audio data serial interface
n Differential analog microphone input
n 26mW/channel stereo headphone amplifier
n 570mW mono high efficiency BTL 8Ω amplifier
n 32-step volume control for audio output amplifiers with
1.5dB step size.
n Unity-gain stable headphone amplifiers
n No snubber networks or bootstrap capacitors are
required by the headphone or hands-free amplifiers
n Adjustable digital side-tone attenuation
n 16-step volume control for microphone preamp with 2dB
step size
n Configurable GPIO/Status Port
n Available in the 42 bump micro-SMD package
Applications
n 2.5 and 3G Mobile Phones and Multimedia Terminals
n PDAs, Internet Appliances and Portable Gaming
n Portable DVD/CD/AAC/MP3 Players
n Digital Cameras and Toys
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2006 National Semiconductor Corporation DS201009
www.national.com