Casio CZ-1 Service Manual And Spare Parts List page 107

19.
SAMPLE
& HOLD
CIRCUIT
TC40S3
Function
TaWa
Input
ON
Cnwtntl
A
a
L L OX,
02
L
H
IX.
OZ
H
L
OX.IZ
H
H
IX, IZ
Signal
SH from
Mattar LSI
^
Signal
SH
from
Slava
LSI
V~
Mattar
Output
Tht
block
eliminates a high
frequency
noise called as
"Glitch"
which appears
at
the
end
of the
stepped waveform.
Signal
SH
from
Mattar LSI
-J
Signal
SH
from
Slava
LSI
Input signal
*
Sampling tima
Mattar output
(pin
7
of
tha
opamp.)
Slava
output
(pin
1
of tha
opamp.)
Pi
When
signal
SH
from Master
LSI
is
HIGH,
the switch
X
in
TC4053
is
contacted with the
terminal
OX. This causes the input
signal
to
pass
through.
At
this
time, the voltage level
of the
waveform
is
charged
in
the
Hold
Capacitor.
On
the other
hand, while
a glitch
appears
on
the
waveform,
the switch
X
is
contacted with
the terminal IX.
This
results in cutting off
the
glitch.
Although no
signal
comes
out of
TC4053,
the input of the
opamp
keeps
the
same
voltage level
by
discharging of the
Hold
Capacitor.
Sampling or holding the
slave
waveform
is
performed by
the
same
procedures using
signal
SH
from
Slave LSI
and
switch Z.
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