ICM7242 Datasheet, PDF (4/7 Pages) Intersil Corporation – Long Range Fixed Timer

ICM7242
To use the 8-bit counter without the timebase, Terminal 7
(RC) should be connected to ground and the outputs taken
from Terminals 2 and 3.
The ICM7242 may be used for a very low frequency square
wave reference. For this application the timing components
are more convenient than those that would be required by a
555 timer. For very low frequencies, devices may be cas-
caded (see Figure 3).
V_DD
1
8R
1
8
C
2
7
2
7
ICM7242
3
6
ICM7242
3
6
4
5
4
5
f = RC/2¹⁶
FIGURE 3. LOW FREQUENCY REFERENCE (OSCILLATOR)
For monostable operation the ÷2⁸ output is connected to the
RESET terminal. A positive edge on TRIGGER initiates the
cycle (NOTE: TRIGGER overrides RESET).
OUTPUT
V_DD
1
8
2
7
ICM7242
3
6
4
5
R
C
TRIGGER
S₁
RESET
100kΩ
Comparing the ICM7242 With the 2242
ICM7242
Operating Voltage
Operating Temperature Range
2V - 16V
-25^oC to 85^oC
Supply Current, V_DD = 5V
Pullup Resistors
0.7mA (Max)
TB Output
No
÷2 Output
No
÷256 Output
No
Toggle Rate
3.0MHz
Resistor to Inhibit Oscillator
No
Resistor in Series with Reset for
No
Monostable Operation
Capacitor TB Terminal for HF
No
Operation
2242
4V - 15V
0^oC to 70^oC
7mA (Max)
Yes
Yes
Yes
0.5MHz
Yes
Yes
Sometimes
By selection of R and C, a wide variety of sequence timing
can be realized. A typical flow chart for a machine tool con-
troller could be as shown in Figure 5.
TRIGGERING CAN BE
OBTAINED FROM A
PREVIOUS STAGE, A
LIMIT SWITCH, OPER-
ATOR SWITCH, ETC.
START
ICM7242
WAIT
5s
ICM7242
ENABLE
10s
STOP
ENABLE
5s
ICM7242
COUNT
TO 185
ICM7240
WAIT
5s
ICM7242
START
STOP
WAIT ENABLE WAIT
5s
10s
5s
COUNT ENABLE
TO 185
5s
TRIGGER
TERMINAL 6
TB OUTPUT
TERMINAL 8
OUTPUT
TERMINAL 3
FIGURE 4. MONOSTABLE OPERATION
The ICM7242 is superior in all respects to the 2242 except
for initial accuracy and oscillator stability. This is primarily
due to the fact that high value p- resistors have been used
on the ICM7242 to provide the comparator timing points.
FIGURE 5. FLOW CHART FOR MACHINE TOOL CONTROLLER
By cascading devices, use of low cost CMOS AND/OR gates
and appropriate RC delays between stages, numerous
sequential control variations can be obtained. Typical appli-
cations include injection molding machine controllers, pho-
nograph record production machines, automatic sequencers
(no metal contacts or moving parts), milling machine control-
lers, process timers, automatic lubrication systems, etc.
Sequence Timing
• Process Control
• Machine Automation
• Electro-Pneumatic Drivers
• Multi Operation (Serial or Parallel Controlling)
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