1FEATURES
2• 16-Bit Resolution Stereo DAC
• I2S Digital Audio Data Serial Interface
• SPI Serial Interface (Control Register)
• Volume Control (32 steps; 1.5 dB Increments)
• Up to 50mW/Channel Stereo Headphone
Amplifier
• Zero Crossing Detection for Silent Attenuation
Steps
• 2.6VDC to 5.0VDC Digital Supply Voltage Range
• 2.6V DC to 5.5VDC Analog Supply Voltage Range
(See (1))
• Unity-Gain Stable Headphone Amplifiers
• Available in the 20-bump DSBGA Package

KEY SPECIFICATIONS
• PSRR at 217Hz, A/DVDD = 3V, (See Figure 1):
52dB (typ)
• POUT at AVDD = 3.0V, 32Ω
– < 0.05% THD: 13mW (typ)
– < 0.05% THD: 26mW (typ)
• Supply Voltage Range
– DVDD: 2,6V to 5.0V
– AVDD: (See (1)) 2.6V to 5.5V
• Shutdown Current: 1μA (typ)

APPLICATIONS
• Mobile Phones
• PDAs
• Portable Electronic Devices

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 communication 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
communication. With AVDD and DVDD = 3.0VDC and
driving a 32Ω single-ended load to a 26mWRMS
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 mobile 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.