LM4921 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – Low Voltage I2S 16-Bit Stereo DAC with Stereo Headphone Power Amplifiers and Volume Control

November 2004
LM4921
Low Voltage I²S 16-Bit Stereo DAC with Stereo
Headphone Power Amplifiers and Volume Control
General Description
The LM4921 combines a 16-bit resolution stereo I²S input
digital-to-analog converter (DAC) with a stereo headphone
audio power amplifier. It is primarily designed for demanding
applications in mobile phones and other portable communi-
cation device applications. The LM4921 features an I²S
serial interface for the digital audio information and a 16-bit
SPI serial interface for internal register control and commu-
nication. With AV_DD and DV_DD = 3.0V_DC and driving a 32Ω
single-ended load to a 26mW_RMS output level the distortion
(THD+N) of the LM4921 will be less than 0.5%. The LM4921
also features a programmable 32-step digital volume control
accessed through an SPI interface.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. It is, therefore, ideally suited for mo-
bile phone and other low voltage applications where minimal
power consumption is a primary requirement.
The LM4921 features a low-power consumption shutdown
mode, and also has an internal thermal shutdown protection
mechanism.
Key Specifications
j PSRR at 217Hz, A/DV_DD = 3V, (Fig. 1)
j P_OUT at AV_DD = 3.0V, 32Ω
< 0.05% THD
< 0.5% THD
j Supply voltage range
DV_DD
AV_DD (Note 8)
j Shutdown current
52dB (typ)
13mW (typ)
26mW (typ)
2.6V to 5.0V
2.6V to 5.5V
1µA (typ)
Features
n 16-bit resolution stereo DAC
n I²S digital audio data serial interface
n SPI serial interface (control register)
n Volume Control (32 steps; 1.5 dB increments)
n Up to 50mW/channel stereo headphone amplifier
n Zero Crossing Detection for Silent Attenuation Steps
n 2.6V_DC to 5.0V_DC digital supply voltage range
n 2.6V_DC to 5.5V_DC analog supply voltage range (Note 8)
n Unity-gain stable headphone amplifiers
n Available in the 20-bump microSMD package
Applications
n Mobile phones
n PDAs
n Portable electronic devices
Boomer^® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation DS200486
www.national.com