DATASHEET
ICM7242
FN2866
Rev 5.00
September 14, 2015
Long Range Fixed Timer
The ICM7242 is a CMOS timer/counter circuit consisting of
an RC oscillator followed by an 8-bit binary counter. It will
replace the 2242 in most applications, with a significant
reduction in the number of external components.
Features
Three outputs are provided. They are the oscillator output,
and buffered outputs from the first and eighth counters.
• Cascadable
Ordering Information
• Wide Supply Voltage Range . . . . . . . . . . . . . . . 2V to 16V
PART
NUMBER
(See Note)
ICM7242IPAZ
7242 IBAZ
• Monostable or Astable Operation
• Low Supply Current . . . . . . . . . . . . . . . . . . . . 115µA at 5V
• Pb-Free Plus Anneal Available (RoHS Compliant)
8 Ld PDIP**
E8.3
Pinout
0 to +70
8 Ld SOIC
M8.15
-25 to +85
8 Ld SOIC
M8.15
-25 to +85
ICM7242CBAZ* 7242 CBAZ
(No longer
available or
supported)
ICM7242IBAZ*
(No longer
available or
supported)
• Timing From Microseconds to Days
PKG.
DWG. #
PART
TEMP.
MARKING RANGE (°C)
7242 IPAZ
PACKAGE
(RoHS
Compliant)
• Replaces the 2242 in Most Applications
*Add “-T” suffix for tape and reel.
ICM7242
(8 LD PDIP, SOIC)
TOP VIEW
VDD
1
8
TB I/O
2 OUT
2
7
RC
128/256 OUT
3
6
TRIGGER
VSS
4
5
RESET
**Pb-free PDIPs can be used for through hole wave solder processing
only. They are not intended for use in Reflow solder processing
applications.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are RoHS compliant and
compatible with both SnPb and Pb-free soldering operations. Intersil
Pb-free products are MSL classified at Pb-free peak reflow
temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020
FN2866 Rev 5.00
September 14, 2015
Page 1 of 11
ICM7242
Functional Block Diagram
R1
50k
+
+
R
R3
50k
Q
Q
S
Q
Q
CL
Q
S
Q
CL
Q
CL
S
Q
S
Q
CL
Q
S
Q
Q
S
Q
CL
Q
1
4
8
5
VDD
VSS
TB I/O
RESET
FN2866 Rev 5.00
September 14, 2015
Q
CL
R
S
-
7
CL
S
-
R2
86k
RC
Q
Q
CL
S
6
Q
2
3
TRIGGER ÷2 OUT ÷128/256
OUTPUT
Page 2 of 11
ICM7242
Absolute Maximum Ratings
Thermal Information
Supply Voltage (VDD to VSS). . . . . . . . . . . . . . . . . . . . . . . . . . . .18V
Input Voltage (Note 1)
Terminals (Pins 5, 6, 7, 8). . . . . . . . . . (VSS -0.3V) to (VDD +0.3V)
Continuous Output Current (Each Output). . . . . . . . . . . . . . . . 50mA
Thermal Resistance (Typical, Note2)
JA (°C/W)
PDIP Package* . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100
SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
160
Maximum Storage Temperature Range . . . . . . . . . -65°C to +150°C
Maximum Junction Temperature (Plastic Package) . . . . . . . +150°C
Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
*Pb-free PDIPs can be used for through hole wave solder
processing only. They are not intended for use in Reflow solder
processing applications.
Operating Conditions
Temperature Range
ICM7242I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-25°C to +85°C
ICM7242C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTES:
1. Due to the SCR structure inherent in the CMOS process, connecting any terminal to voltages greater than VDD or less than VSS may cause
destructive device latchup. For this reason, it is recommended that no inputs from external sources not operating on the same supply be applied
to the device before its supply is established and, that in multiple supply systems, the supply to the ICM7242 be turned on first.
2. JA is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
VDD = 5V, TA = +25°C, R = 10k, C = 0.1µF, VSS = 0V, Unless Otherwise Specified
PARAMETER
SYMBOL
Guaranteed Supply Voltage
VDD
Supply Current
IDD
TEST CONDITIONS
MIN
TYP
MAX
UNITS
2
-
16
V
Reset
-
125
-
µA
Operating, R = 10k, C = 0.1µF
-
340
800
µA
Operating, R = 1M, C = 0.1µF
-
220
600
µA
TB Inhibited, RC Connected to VSS
-
225
-
µA
-
5
-
%
Timing Accuracy
RC Oscillator Frequency Temperature
Drift
f/t
Independent of RC Components
-
250
-
ppm/°C
Time Base Output Voltage
VOTB
ISOURCE = 100µA
-
3.5
-
V
ISINK = 1.0mA
-
0.40
-
V
Time Base Output Leakage Current
ITBLK
RC = Ground
-
-
25
µA
Trigger Input Voltage
VTRIG
VDD = 5V
-
1.6
2.0
V
VDD = 15V
-
3.5
4.5
V
VDD = 5V
-
1.3
2.0
V
VDD = 15V
-
2.7
4.0
V
-
10
-
µA
-
1
-
MHz
2
6
-
MHz
-
13
-
MHz
Reset Input Voltage
Trigger/Reset Input Current
Max Count Toggle Rate
VRST
ITRIG, IRST
fT
VDD = 2V
VDD = 5V
Counter/Divider Mode
VDD = 15V
50% Duty Cycle Input with Peak to Peak
Voltages Equal to VDD and VSS
Output Saturation Voltage
VSAT
All Outputs Except TB Output VDD = 5V,
IOUT = 3.2mA
-
0.22
0.4
V
Output Sourcing Current
ISOURCE
VDD = 5V Terminals 2 and 3, VOUT = 1V
-
300
-
µA
10
-
-
pF
1k
-
22M
MIN Timing Capacitor (Note 3)
CT
Timing Resistor Range (Note 3)
RT
VDD = 2 - 16V
NOTE:
3. For design only, not tested.
FN2866 Rev 5.00
September 14, 2015
Page 3 of 11
ICM7242
Test Circuit
VDD
÷21 (RC/2) OUTPUT
÷28 (RC/256) OUTPUT
1
8
2
7
3
6
4
5
RESET
TIME BASE INPUT/OUTPUT
C
VDD
R
TRIGGER
TIME BASE PERIOD = 1.0RC;
1s = 1M x 1µF
NOTE:
4. 21 and 28 outputs are inverters and have active pullups.
Application Information
Operating Considerations
Shorting the RC terminal or output terminals to VDD may
exceed dissipation ratings and/or maximum DC current limits
(especially at high supply voltages).
There is a limitation of 50pF maximum loading on the TB I/O
terminal if the timebase is being used to drive the counter
section. If higher value loading is used, the counter sections
may miscount.
For greatest accuracy, use timing component values shown
in Figure 8. For highest frequency operation it will be
desirable to use very low values for the capacitor; accuracy
will decrease for oscillator frequencies in excess of 200kHz.
The timing capacitor should be connected between the RC
pin and the positive supply rail, VDD , as shown in Figure 1.
When system power is turned off, any charge remaining on
the capacitor will be discharged to ground through a large
internal diode between the RC node and VSS. Do NOT
reference the timing capacitor to ground, since there is no
high current path in this direction to safely discharge the
capacitor when power is turned off. The discharge current
from such a configuration could potentially damage the
device.
When driving the counter section from an external clock, the
optimum drive waveform is a square wave with an amplitude
equal to the supply voltage. If the clock is a very slow ramp
triangular, sine wave, etc., it will be necessary to “square up”
the waveform; this can be done by using two CMOS
inverters in series, operating from the same supply voltage
as the ICM7242.
The ICM7242 is a non-programmable timer whose principal
applications will be very low frequency oscillators and long
range timers; it makes a much better low frequency
oscillator/timer than a 555 or ICM7555, because of the onchip 8-bit counter. Also, devices can be cascaded to produce
extremely low frequency signals.
Because outputs will not be ANDed, output inverters are
used instead of open drain N-Channel transistors, and the
FN2866 Rev 5.00
September 14, 2015
external resistors used for the 2242 will not be required for
the ICM7242. The ICM7242 will, however, plug into a socket
for the 2242 having these resistors.
The timing diagram for the ICM7242 is shown in Figure 1.
Assuming that the device is in the RESET mode, which
occurs on power up or after a positive signal on the RESET
terminal (if TRIGGER is low), a positive edge on the trigger
input signal will initiate normal operation. The discharge
transistor turns on, discharging the timing capacitor C, and
all the flip-flops in the counter chain change states. Thus, the
outputs on terminals 2 and 3 change from high to low states.
After 128 negative timebase edges, the 28 output returns to
the high state.
TRIGGER INPUT
(TERMINAL 6)
TIMEBASE INPUT
(TERMINAL 8)
÷2 OUTPUT
(TERMINAL 2)
128RC
÷128/256 OUTPUT
(TERMINAL 3) (ASTABLE
OR “FREE RUN” MODE)
128RC
÷128/256 OUTPUT
(TERMINAL 3)
(MONOSTABLE
OR “ONE SHOT” MODE)
128RC
FIGURE 1. TIMING DIAGRAMS OF OUTPUT WAVEFORMS
FOR THE ICM7242 (COMPARE WITH FIGURE 5)
VDD
fIN/2
OUTPUTS
fIN/256
fIN
1
8
2
7
3
6
4
5
>3/4 (V+)