PRODUCT INFORMATION
AC’97 Revision 2.3 Codecs
AC’97 rev 2.3 Audio Codecs with Internal Jack-Sense and Paging Registers
INTRODUCTION
The STAC9752/53 are the industry’s first AC’97 2.3 Audio Codecs for the PC and portable segment. Both
codes are 20-Bit AC’97 devices adhering to Intel’s newly released 2.3 specification. The new version adds
important usability features like integrated Jack-Sense and Paging Registers to the already rich feature set that
includes integrated headphone amplifier, SPDIF output,
and the Crystal elimination Circuit. The most important
aspect of AC’97 version 2.3 is the cost saving potential of
the Internal Jack Sense capability. The Internal Jack-
Sense can determine what has been plugged into the
audio connectors and alert end-users when they have
made a mistake. This helps the end-user get their
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system setup quickly, and it keep audio technical support
call costs down for the OEM. Right now the largest
support call item is audio setup … 2.3 codecs with
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Internal Jack-Sense can really help keep that cost down.
($40/hour for call support) x (15minutes per call) = $10 Savings
OEM cost savings from Internal Jack-Sense is the drive for AC’97 2.3
MARKET OPPORTUNITY
Audio has moved full force to the motherboard in the last year, especially with the introduction of 20-bit south
bridge controllers such as the 845 chipset from Intel. This is a very important development for SigmaTel’s line
of 20-bit codecs. With the STAC9752/53, and the soon to be announced 6-ch STAC9758/59, SPDIF output,
standard motherboards can now more easily become part of today’s home entertainment system with a full 6-
channels audio playback from the PC. Given the growing importance of multi-channel games, DVD playback
and home theater, the AC’97 2.3 Internal Jack-Sense codecs are becoming essential to help end-users set their
systems up for the first time. Every time someone calls the OEM for technical support, it costs the OEM
$40 per hour on lost profits. With average call times of 15 minutes, each call costs the OEM roughly $10
per confused end-user. The family of AC’97 2.3 parts from SigmaTel help eliminate the confusion, the poor
end-user experience, and the lost OEM profits.
AC97 REVISION 2.3 TECHNICAL FEATURES
The newly released AC’97 revision 2.3 specification has recently been upgraded with several new features
that greatly improve the end-user experience. These new features include Internal Jack-Sense that lets the PC
determine what type of device … such as speaker, headphones, and various microphones … is actually plugged
into the audio connectors. The headphone, line-out, and microphone all incorporate SigmaTel’s Internal
Jack-sense capability that does not require any external components. This means that SigmaTel’s Jack-
Sense works on existing MBs without any modifications. In addition to the Jack-Sense, the new AC’97 2.3
specification provides for Paging Registers that store key audio sub-system information like external amplifier
settings, gain, phase, and location of connectors. This type of information is very important to Microsoft in their
progress for improved business audio. Without this type of Analog Plug-n-Play information the key features of
business audio are very difficult to implement for voice record, speech recognition, and better use of the PC for
telephony. The standard GPIO Jack-Sense pins are still available for designs that have previously implemented
the older style mechanical approach to jack-sense that depended on special high-cost connectors with customer
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