STAC9708 Datasheet, PDF (38/56 Pages) List of Unclassifed Manufacturers – Multi-Channel AC97 Codec With Multi-Codec Option

SigmaTel, Inc.
Preliminary
STAC9708/11
8. EXTENDED CODEC FUNCTIONALITY
8.1 Anti-Pop Circuitry
The STAC9708/11 provides an integrated output signal (APOP on pin 34) to aid in low-component-count anti-
pop implementations. An audible speaker "pop" can occur when the main power is applied to, or removed from,
the codec or audio output amplifier. In ac coupled systems, the speaker sided of the ac coupling capacitor is
shunted to ground through a transistor or FET; this prevents audible pops when the system is powering on and
off. A +10 uF capacitor on CAP1 provides a delay to hold-off power to the output stages on power up. A +22 uF
capacitor provides reserve power to sustain the output shunting action until the power has been fully removed on
power down. APOP is active logic high during shunting operations; APOP is at logic low during normal
operations.
9. AC TIMING CHARACTERISTICS
(Tambient = 25 °C, AVdd = DVdd = 5.0V or 3.3V ± 5%, AVss=DVss+0V; 50pF external load)
9.1 Cold Reset
Figure 14. Cold Reset
RESET#
BIT_CLK
Tres_low
Trst2clk
Table 23. Cold Reset
PARAMETER
RESET# active low pulse width
RESET# inactive to BIT_CLK startup delay
SYMBOL
Tres_low
Trst2clk
MIN
1.0
162.8
TYP
-
-
MAX
-
-
UNITS
us
ns
# denotes active low.
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10/02/98