SNAS276F – MAY 2005 – REVISED APRIL 2013
LM4550B AC '97 Rev 2.1 Multi-Channel Audio Codec with Stereo Headphone Amplifier,
Sample Rate Conversion and TI 3D Sound
Check for Samples:
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FEATURES
AC '97 Rev 2.1 Compliant
High Quality Sample Rate Conversion from 4
kHz to 48 kHz in 1 Hz Increments
Supports up to 6 DAC Channel Systems with
Multiple LM4550Bs or with Other TI LM45xx
Codecs
Unique TI Chaining Function Shares a Single
Controller SDATA_IN Pin Among Multiple
Codecs
Stereo Headphone Amp with Separate Gain
Control
Texas Instruments' 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
DESCRIPTION
The LM4550B 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 LM4550B provides 90 dB of Dynamic
Range.
The LM4550B 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
LM4550B provides a stereo headphone amplifier as
one of its stereo outputs and also 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 LM4550B suitable
for non-PC codec applications.
The LM4550B features the ability to connect several
codecs together in a system to provide up to 6
simultaneous channels of streaming data on Output
Frames (Controller to Codec) for surround sound
applications. Such systems can also support up to 8
simultaneous channels of streaming data on Input
Frames (Codec to Controller). Multiple codec systems
can be built either using the standard AC Link
configuration (i.e. of one serial data signal to the
Controller per codec) or using a unique Texas
Instruments feature for chaining codecs together.
This chain feature shares only a single data signal to
the controller among multiple codecs.
The AC '97 architecture separates the analog and
digital functions of the PC audio system allowing both
for system design flexibility and increased
performance.
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APPLICATIONS
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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 Audio Frequency Systems Requiring
2, 4 or 6 DAC Channels and/or up to 8 ADC
Channels
Automotive Telematics
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KEY SPECIFICATIONS
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Analog Mixer Dynamic Range, 97dB (Typ)
DAC Dynamic Range, 89dB (Typ)
ADC Dynamic Range, 90dB (Typ)
Headphone Amp THD+N at 50 mW,
0.02% (typ) into 32Ω
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
Copyright © 2005–2013, Texas Instruments Incorporated
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.
TI [ TEXAS INSTRUMENTS ]
