LM4546A Datasheet, PDF (1/28 Pages) National Semiconductor (TI) – AC 97 Rev 2 Multi-Channel Audio Codec with Sample Rate Conversion and National 3D Sound

LM4546A
OBSOLETE
July 15, 2009
AC '97 Rev 2 Multi-Channel Audio Codec with Sample Rate
Conversion and National 3D Sound
General Description
The LM4546A is an audio codec for PC systems which is fully
PC98 compliant and performs the analog intensive functions
of the AC '97 Rev 2 architecture. Using 18-bit Sigma-Delta
ADCs and DACs, the LM4546A provides 90 dB of Dynamic
Range.
The LM4546A 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 LM4546A supports
National's 3D Sound stereo enhancement and a comprehen-
sive 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 fea-
tures together with an extended temperature range also make
the LM4546A suitable for non-PC codec applications.
The LM4546A 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.
LM4546A 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 mul-
tiple codecs. The LM4546A may also be used in systems with
the National LM4550 to support up to 6 simultaneous chan-
nels 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.
Key Specifications
■ ^{Analog Mixer Dynamic Range}
■ ^{DAC Dynamic Range}
■ ^{ADC Dynamic Range}
97 dB (typ)
89 dB (typ)
90 dB (typ)
Features
■ ^{AC '97 Rev 2 compliant}
■ ^{High quality Sample Rate Conversion from 4 kHz to 48}
kHz in 1 Hz increments
■ ^{Multiple codec support}
■ ^{National's 3D Sound stereo enhancement circuitry}
■ ^{Advanced power management support}
■ ^{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}
© 2009 National Semiconductor Corporation 200308
200308 Version 5 Revision 1 Print Date/Time: 2009/07/15 15:26:52
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