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SigmaTel, Inc.
Data Sheet
STAC9721
9
04/07/00
04/07/00
1.3 Filter/References/GPIO
These signals are connected to resistors, capacitors, specific voltages, or provide general purpose I/O.
Table 5. Filtering and Voltage References
Signal Name
Type
Description
Vref
O
Reference Voltage
Vrefout
O
Reference Voltage out 5mA drive (intended for mic
bias)
AFILT1
O
Anti-Aliasing Filter Cap - ADC channel
AFILT2
O
Anti-Aliasing Filter Cap - ADC channel
CAP1
O
Analog Output Hold-Off Delay
CAP2
O
ADC reference Cap
CAP3
O
Anti-Pop Power Sustain Delay
APOP
O
Anti-Pop Output Ground Shunt Control
EAPD
O
External Amplifier Power Down Control
1.4 Power and Ground Signals
Table 6. Power Signal List STAC9721/23
Signal Name
Type
STAC9721
STAC9723
AVdd1
I
Analog Vdd = 5.0V
Analog Vdd = 3.3V
AVdd2
I
Analog Vdd = 5.0V
Analog Vdd = 3.3V
AVss1
I
Analog Gnd
Analog Gnd
AVss2
I
Analog Gnd
Analog Gnd
DVdd1
I
Digital Vdd = 5.0V or 3.3V
Digital Vdd = 3.3V
DVdd2
I
Digital Vdd = 5.0V or 3.3V
Digital Vdd = 3.3V
DVss1
I
Digital Gnd
Digital Gnd
DVss2
I
Digital Gnd
Digital Gnd
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