FEATURES
• AC '97 Rev 2.1 Compliant
• High Quality Sample Rate Conversion from 4
kHz to 48 kHz in 1 Hz Increments
• Multiple Codec Support
• Texas Instruments' 3D Sound Stereo
Enhancement Circuitry
• Advanced Power Management Support
• Digital 3.3V and 5V Supply Options
• Extended Temperature: −40°C ≤ TA ≤ 85°C

APPLICATIONS
• Desktop PC Audio Systems on PCI Cards,
AMR Cards, or with Motherboard Chips Sets
Featuring AC Link
• Portable PC Systems as on MDC Cards, or
with a Chipset or Accelerator Featuring AC
Link
• General and Multi-channel Audio Frequency
Systems
• Automotive Telematics

KEY SPECIFICATIONS
• Analog Mixer Dynamic Range 97 dB (typ)
• DAC Dynamic Range 89 dB (typ)
• ADC Dynamic Range 90 dB (typ)

DESCRIPTION
The LM4546B is an audio codec for PC systems
which is fully PC99 compliant and performs the
analog intensive functions of the AC '97 Rev 2.1
architecture. Using 18-bit Sigma-Delta ADCs and
DACs, the LM4546B provides 90 dB of Dynamic
Range.
The LM4546B was designed specifically to provide a
high quality audio path and provide all analog
functionality in a PC audio system. It features full
duplex stereo ADCs and DACs and analog mixers
with access to 2 stereo and 2 mono inputs. Each
mixer input has separate gain, attenuation and mute
control and the mixers drive 1 mono and 1 stereo
output, each with attenuation and mute control. The
LM4546B supports Texas Instruments' 3D Sound
stereo enhancement and a comprehensive sample
rate conversion capability. The sample rate for the
ADCs and DACs can be programmed separately with
a resolution of 1 Hz to convert any rate in the range 4
kHz – 48 kHz. Sample timing from the ADCs and
sample request timing for the DACs are completely
deterministic to ease task scheduling and application
software development. These features together with
an extended temperature range also make the
LM4546B suitable for non-PC codec applications.
The LM4546B features the ability to connect several
codecs together using the Extended AC Link
configuration of one dedicated serial data signal to
the Controller per codec. LM4546B systems support
up to 8 simultaneous channels of streaming data on
Input Frames (Codec to Controller) while Output
Frames (Controller to Codec) carry 2 streams to
multiple codecs. The LM4546B may also be used in
systems with the Texas Instruments LM4550 to
support up to 6 simultaneous channels of streaming
data on Output Frames.
The AC '97 architecture separates the analog and
digital functions of the PC audio system allowing both
for system design flexibility and increased
performance.