LM4546_09 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – AC 97 Rev 2 Codec with Sample Rate Conversion and National 3D Sound

LM4546
OBSOLETE
April 29, 2009
AC '97 Rev 2 Codec with Sample Rate Conversion and
National 3D Sound
General Description
The LM4546 is an audio codec for PC systems which is fully
PC98 compliant and performs the analog intensive functions
of the AC97 Rev 2 architecture. Using 18-bit Sigma-Delta A/
D's and D/A's, the LM4546 provides 90dB of Dynamic Range.
The LM4546 was designed specifically to provide a high qual-
ity audio path and provide all analog functionality in a PC
audio system. It features full duplex stereo A/D's and D/A's
and an analog mixer with 2 stereo and 3 mono inputs, each
of which has separate gain, attenuation and mute control. The
LM4546 also provides National's 3D Sound stereo enhance-
ment.
The LM4546 supports variable sample rate conversion as de-
fined in the AC97 Rev2 specification. The sample rate for the
A/D and D/A can be programmed separately to convert any
rate between 4kHz - 48kHz with a resolution of 1Hz. The
AC97 architecture separates the analog and digital functions
of the PC audio system allowing both for system design flex-
ibility and increased performance.
Key Specifications
■ ^{Analog Mixer Dynamic Range}
■ ^{D/A Dynamic Range}
■ ^{A/D Dynamic Range}
97dB (typ)
89dB (typ)
90dB (typ)
Features
■ ^{AC'97 Rev 2 compliant}
■ ^{National's 3D Sound circuitry}
■ ^{High quality Sample Rate Conversion (SRC) from 4kHz to}
48kHz in 1Hz increments
■ ^{Multiple Codec support}
■ ^{Advanced power management support}
■ ^{Digital 3V and 5V compliant}
Applications
■ ^{Desktop PC Audio Systems}
■ ^{Portable PC Systems}
■ ^{Mobile PC Systems}
Block Diagram
FIGURE 1. LM4546 Block Diagram
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© 2009 National Semiconductor Corporation 100985
100985 Version 4 Revision 1 Print Date/Time: 2009/04/29 09:52:43
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