CDP1805 Intersil Corporation, CDP1805 Datasheet - Page 14

• Manufacturer Part Number: CDP1805
• Description: CMOS 8-Bit Microprocessor with On-Chip RAM and Counter/Timer
• Manufacturer: Intersil Corporation

Because of the Schmitt Trigger input, an RC oscillator can
be used as shown in Figure 9. The frequency is approxi-
mately 1/RC (see Figure 10).
†
†
Pin numbers refer to 40 pin DIP.
Pin numbers refer to 40 pin DIP.
FIGURE 8. TYPICAL 5MHz CRYSTAL OSCILLATOR
GEC
DTC
TPA
FIGURE 9. RC NETWORK FOR OSCILLATOR
EF1
EF2
CLOCK†
CLOCK†
STPC
15pF
C
C
IN
1
1
5MHz PARALLEL
RESONANT
32
R
CRYSTAL
SCMI
XTAL
1M
RF
R
SPMI
SCM2
SPM2
STM
39 XTAL †
39 XTAL †
C
27pF
FIGURE 7. TIMER/COUNTER DIAGRAM
CDP1805AC, CDP1806AC
OUT
COUNTER
DOWN
READ
8-BIT
INH
LOAD
OUT
14
FIGURE 10. NOMINAL COMPONENT VALUES AS A FUNCTION
CLEAR
UNDERFLOW
COUNTER
100K
10M
L
L
H
H
10K
1M
1
V
ETQ
LDC
OF FREQUENCY FOR THE RC OSCILLATOR
DD
= 5V AT 25
WAIT
10
H
H
L
L
CONTROL MODES
o
100
C
FREQUENCY (Hz)
TO INTERRUPT LATCH
1K
C
D
Q FF
Not Allowed
MODE
Pause
Reset
Q
Q
10K
Run
Q OUTPUT
100K
1M