Sony CXD2701Q Data Book page 48

SONY
CXDS554IAP
Description
of
Functions
A. Soft
muting
The
soft
mute
function
mutes
or
demutes
output data
on the basis
of
a muting time
of
1024/fs
(CD:
fs
=
44.1 kHz).
B, Digital
attenuator
Output data can be
attenuated by
use
of
data transferred
from
an
external
micro computer.
The
ATT
data comprises
8
bits. Bit
Dr
is
the digital
de-emphasis
control
bit,
whereas
bits
Ds through Da
constitute attenuator data.
(1)
Command
input
and
audio output
The
attenuator data
is
in
7
bits,
allowing selection
of
127
different settings.
The
relation
between
a
command
and
output
is
shown
in
the following table.
Attenuator data
DetO
Do
Audio
output
7F«
dB
7E-!
to
OTihi
-0.13
dB
to
-42.144dB
00;h;
—
OO
An
attenuator value
between
01™
and
7E:h.
can be
calculated
by
the following equation.
ATT .
29
tag
(*Pfif*
)dB
Example) Suppose
that attenuator
data
is
7A.
ATT
= 20
log
fl||l
dB = -0.417 dB
C, I/O
synchronizing
circuit
1)
Theory
of
operation
The
synchronizing
circuit
opens
a
window
for six internal
system
clocks,
CK2
(fx/4),
to
monitor
whether
the differentiated signal of the
rise of
LRCK
(LRCKf)
that
may
be
input exists
in
it:
If
the
LRCK
f
is
out
of
the
window
when
the
power
supply
is
turned on, the synchronizing
circuit
holds
the
CK2
at
the time
it
is
in
the center
of the
window, and
lets
it
start
as soon as
the
next
LRCK
f arrives.
This operation synchronizes
an
external
system and
this IC,
and
lines
up
the
phases
of
serial
input data.
2)
Re
-synchronization
by INIT
if
the
LRCK
f
is
in
the
window when
the
power
supply
is
turned
on,
a
fluctuation of
LRCK
could
cause
de-synchronization during operation
of
the IC
(particularly
when
it
is at
either
ero
of
the
window).
For
this
reason, re-synchronization
must always be achieved
after
the
power
supply has
been
turned
on.
The
operation
for
re-synchronization
is
performed
at
the time the INIT
rises.
Tie
operation
initializes
the synchronizing
circuit to
cause a temporary
de-synchronization
and
then
achieves
re -synchronization,
thereby positioning the
LRCK
f
in
the center
of
the
window.
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