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CO
P
8
2
0
C
J/
C
O
P8
22
C
J/
C
O
P8
23
C
J
Oscillator Circuits
EXTERNAL OSCILLATOR
CKI can be driven by an external clock signal provided it
meets the specified duty cycle, rise and fall times, and input
levels. CKO is available as a general purpose input G7
and/or Halt control.
CRYSTAL OSCILLATOR
By selecting CKO as a clock output, CKI and CKO can be
connected to create a crystal controlled oscillator. Table I
shows the component values required for various standard
crystal values.
R/C OSCILLATOR
By selecting CKI as a single pin oscillator, CKI can make a
R/C oscillator. CKO is available as a general purpose input
and/or HALT control. Table II shows variation in the oscilla
tor frequencies as functions of the component (R and C)
values.
Functional Description
(Continued)
TABLE I. Crystal Oscillator Configuration
R1
R2
C1
C2
CKI Freq.
Conditions
(kn)
(Mft)
(PF)
(PF)
(MHz)
0
1
30
30-36
10
Vcc = 5V
0
1
30
30-36
4
VCC = 5V
5.6
1
100
100-156
0.455
>
in
II
o
o
>
TABLE II. RC Oscillator Configuration (Part-To-Part Variation)
R
C
CK1 Freq.
Instr. Cycle
Conditions
(kfl)
(PF)
(MHz)
(jxs)
3.3.
82
2.2 to 2.7
3.7 to 4.6
>
in
II
o
£
5.6
100
1.1 to 1.3
7.4 to 9.0
>
in
II
o
o
>
6.8
100
0.9 to 1.1
8.8 to 10.8
>
in
II
o
o
>
CKI
CKO
J I T
EXTERNAL
CLOCK
T
RESTART
CKI
CKO
T T ^ t
CC RESTART
TL/DD/11208-7
FIGURE 5. Clock Oscillator Configurations
1-58