-------------------------------------------------------HMCS44C,HMCS44CL
• OSCILLATOR
The HMCS44C contains its own oscillator and frequency di-
vider (CPO). The user can obtain the desired timing for opera-
tion
of
the
LSI
by
merely connecting an resistor Rf or ceramic
filter circuit (Internal Clock Operation).
The
OSC
I
clock frequency
is
internally divided
by
four to pro-
duce the internal system clocks.
The user may exchange the external parts for the same LSI to
select either
of
these
two
operational modes as shown in Figure
24.
There
is
no need of specifying it
by
using the mask option.
(a)
Internal Clock Operation Using Resistor
Rt
Wiring
of
OSC. and OSCz terminals should be
as
short
as
possible because the oscillation frequency is
modified
by
capacitance
of
these terminals.
(b)
Internal Clock Operation Using Ceramic Filter Circuit (Built-in
CPG
; Ceramic Filter Oscillator)
(This
is
not
applied
to
HMCS44Cl.)
Ceramic
pC'
Filter
C2
GND
OSC.
Ceramic
Filter:
CSB400P (MURATA)
At
:
lMO:!:10%
C. : 2200pF±
10%
(ceramic capacitor)
C2
: 4 70pF:!:
10%
(ceramic capacitor)
F
C
•
_-
.......
--10SC.
~~~~mic
~
C2
--+--IOSCz
'-----
Ceramic
Filter:
FCR-400K (TDK)
R,
:
lMO±10%
C. l000pF:!:
10%
(ceramic capacitor)
C2
: l000pF:!:
10%
(ceramic capacitor)
The.
ceramic filter oscillation does
not
apply when using "Halt" and
not
resetting at the time
of
"Halt" cancellation.
This circuit is the example
of
the typical
use.
As the oscillation
characteristics is
not
guaranteed. please consider and examine the
circuit constants carefully on your application.
Figure
24
Clock Operation Mode
55
DUty=-TT'T
xl00%
h+
I
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