CS4237B Datasheet, PDF (88/114 Pages) Cirrus Logic – CrystalClear Advanced Audio System with 3D Sound

CS4237B
VDF
UP
DOWN
MUTE
10 k Ω
10 k Ω
100 Ω
100 Ω
100 pF
100 pF
10 k Ω
100 Ω
100 pF
Up
Down
Mute
GND
Figure 24. Volume Control Circuit
In the first format, where VCF1,0 = 00, the mute
function is a toggle or push-on/push-off style.
When the MUTE pin is low, the master out vol-
ume is muted. Pressing the up or down buttons
have no effect while the mute switch is on.
In the second format, where VCF1,0 = 01, the
mute function is a momentary switch (similar to
up and down). When MUTE goes low the mas-
ter out volume mutes if it was un-muted and
vise-versa (the mute button alternates between
mute and un-mute). If the master volume is
muted and up or down is pressed, the volume
automatically un-mutes.
In the third format, where VCF1,0 = 10, the
MUTE pin is not used. This is a two-button for-
mat where pressing up and down simultaneously
mutes the master volume. If the master volume
is muted and up or down is individually pressed,
the volume automatically un-mutes.
The three formats listed above as illustrated in
Figure 25.
A fourth format for mute exists, where
VCF1,0 = 11, which is backwards compatible
with the CS4236. This mode is similar to the
two button mode, except the MUTE pin is used
as the up function and the UP pin is not used.
Crystal / Clock
Two pins have been allocated to allow the inter-
facing of a crystal oscillator: XTALI and
XTALO. The crystal should be designed as fun-
damental mode, parallel resonant, with a load
capacitor of between 10 and 20 pF. The capaci-
tors connected to each of the crystal pins should
be twice the load capacitance specified to the
crystal manufacturer.
An external CMOS clock may be connected to
the crystal input XTALI in lieu of the crystal.
When using an external CMOS clock, the
XTALO pin must be left floating with no trace
or external connection of any kind.
General Purpose Output Pins
Two general purpose outputs are provided to en-
able control of external circuitry (i.e. mute
function). XCTL1 and XCTL0 in the WSS
Codec register I10 are output directly to the ap-
propriate pin when enabled.
Pin XCTL0/XA2 becomes an output for XCTL0
whenever the resource data for the CDROM or
Synthesizer specifies a logical device address
Up
Down
Mute
GND
VCF1,0 = 00
Up
Down
Mute
GND
VCF1,0 = 01
Up
Down
Mute
GND
VCF1,0 = 10
Figure 25. Volume Control Formats
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DS213PP4