LM4549A Datasheet, PDF (1/35 Pages) National Semiconductor (TI) – AC ’97 Rev 2.1 Codec with Sample Rate Conversion and National 3D Sound

OBSOLETE
LM4549
www.ti.com
SNOS987E – NOVEMBER 2002 – REVISED APRIL 2013
LM4549A AC '97 Rev 2.1 Multi-Channel Audio Codec with Sample Rate Conversion and TI
3D Sound
Check for Samples: LM4549
FEATURES
1
•2 AC '97 Rev 2.1 Compliant
• High Quality Sample Rate Conversion from 4
kHz to 48 kHz in 1 Hz Increments
• Multiple Codec Support
• True Line Level Output with Separate Gain
Control
• TI's 3D Sound Stereo Enhancement Circuitry
• Advanced Power Management Support
• External Amplifier Power Down (EAPD)
Control
• PC-Beep Passthrough to Line Out During
Initialization or Cold Reset
• Digital 3.3V and 5V Supply Options
• Extended Temperature: −40°C ≤ T_A ≤ 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
KEY SPECIFICATIONS
• Analog Mixer Dynamic Range: 97 dB (typ)
• DAC Dynamic Range: 89 dB (typ)
• ADC Dynamic Range: 90 dB (typ)
DESCRIPTION
The LM4549A 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 LM4549A provides 90 dB of Dynamic
Range.
The LM4549A 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 4 stereo and 4 mono inputs. Each
mixer input has separate gain, attenuation and mute
control and the mixers drive 1 mono and 2 stereo
outputs, each with attenuation and mute control. The
LM4549A supports TI's 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
LM4549A suitable for non-PC codec applications.
The LM4549A 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. LM4549A 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 LM4549A may also be used in
systems with the TI 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.
1
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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