~------------------------------------------------------HMCS45C,HMCS45CL
Both input and output are at high impedance
state.
Since an input circuit
is
OFF, any current
other than the
Stand-by
Supply
Current (or Halt
Current) does not
flow
even if an input signal
changes.
45C
gets into operation from the status just before the Halt State.
The halt timing
is
shown
in
Figure
23.
CAUTION
If, during the Halt State, the external reset input
is
applied
(RESET =
"1"
("High"
leve!),
the internal status
is
not held.
When the
Hr:T
pin
is
set to
"1"
("High" level), the HMCS-
Vcc
________________
~
HIT
~------------------tHLT--------------~
..
Figure
23
Halt Timing
• OSCILLATOR
The HMCS45C 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
Rf
Wiring
of
OSC, and
OSC2
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 HMCS45Cl.)
~
C'
__
--.--IOSC,
~i~::rmic
c::I
C2
-+----,
OSC2
GND
~------
Ceramic
Filter:
CSB400P (MURATA)
R,
: 1MO:!:10%
C,
: 2200pF:!:
10%
(ceramic capacitor)
C2
: 47OpF:!: 10% (ceramic capacitor)
F
C
'
_-_-IOSC,
~~:e~miC
c::I
Rf
C2
.....
--
.......
-IOSC2
L.--
__
Ceramic
Filter:
FCR-400K (TDK)
RI
: 1MO:!:10%
C,
1
000
pF
!:
10%
(ceramic capacitor)
C2
: 1000pF!
10%
(ceramic capacitor)
The ceramic filter oscillation does not apply when using
"Half'
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.
(c)
Exte,.o' C'ock Ope'O.O"
(E.te,.o'
CP~
T.,
T'J-=
~n
:::
2=~
3:;
V
Duty=
_T_I_
x
100%
Th+TI
Figure
24
Clock Operation Mode
77
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