STAC9708 Datasheet, PDF (52/56 Pages) List of Unclassifed Manufacturers – Multi-Channel AC97 Codec With Multi-Codec Option

SigmaTel, Inc.
Preliminary
STAC9708/11
Appendix B
+5.0V/+3.3V POWER SUPPLY OPERATION NOTES
The STAC9708 is capable of operating from a single 5V supply connected to both DVdd and AVdd. Even though
the STAC9708 has digital switching levels of 0.2Vdd to 0.5Vdd (See AC Link Electrical Characteristics in this
data book), we recommend that all digital interface signals to the AC-Link be 5V. If digital interface signals
below 5V are used, then appropriate level shifting circuitry must be provided to ensure adequate digital noise
immunity.
The STAC9708 can also operate from a 3.3V digital supply connected to DVdd while maintaining a 5V analog
supply on AVdd. On-chip level shifters ensure accurate logic transfers between the analog and digital portions of
the STAC9708. If digital interface signals above 3.3V are used (i.e. a +5V AC-Link interface), then appropriate
level shifting circuitry must be provided to ensure adequate digital noise immunity and to prevent on-chip ESD
protection diodes from turning on. (See Appendixes A concerning SPLIT INDEPENDENT POWER SUPPLY
OPERATION).
The STAC9711 must be run from a 3.3V supply connected to both DVdd and AVdd. If digital interface signals
above 3.3V are used (i.e. a +5V AC-Link interface), then appropriate level shifting circuitry must be provided to
ensure adequate digital noise immunity and to prevent on-ship ESD protection diodes from turning on.
*Always operate the STAC97xx digital supply from the same supply voltage as the digital controller
supply.
*All the analog inputs must be ac-coupled with a capacitor of 3.3 uF or greater. It is recommended that a
resistor of about 47KΩ be connected from the signal side of the capacitor to analog GND as shown below.
SIGNAL
> 3.3 uF
47K
Analog Input
*All the analog outputs must be ac-coupled. If an external amplifier is used, make sure that the input
impedance of the amplifier is at least 10KΩ and use an ac-coupling capacitor of 3.3 uF.
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