The ICM7555 and ICM7556 are CMOS RC timers providing
significantly improved performance over the standard
SE/NE555/6 and 355 timers, while at the same time being
direct replacements for those devices in most applications.
Improved parameters include low supply current, wide
operating supply voltage range, low THRESHOLD,
TRIGGER
and RESET currents, no crowbarring of the
supply current during output transitions, higher frequency
performance and no requirement to decouple CONTROL
VOLTAGE for stable operation.
Specifically, the ICM7555 and ICM7556 are stable
controllers capable of producing accurate time delays or
frequencies. The ICM7556 is a dual ICM7555, with the two
timers operating independently of each other, sharing only
V+ and GND. In the one shot mode, the pulse width of each
circuit is precisely controlled by one external resistor and
capacitor. For astable operation as an oscillator, the free
running frequency and the duty cycle are both accurately
controlled by two external resistors and one capacitor. Unlike
the regular bipolar 555/6 devices, the CONTROL VOLTAGE
terminal need not be decoupled with a capacitor. The circuits
are triggered and reset on falling (negative) waveforms, and
the output inverter can source or sin k currents large enough
to drive TTL loads, or provi de minima l offsets to dri ve CMOS
loads.
Applications
• Precision Timing
• Pulse Generation
• Sequential Timing
• Time Delay Generation
• Pulse Width Modulation
• Pulse Position Modulation
• Missing Pulse Detector
FN2867.6
Features
• Exact Equivalent in Most Cases for SE/NE555/556 or
TLC555/556
CAUTION: Stresses above those listed in “Absolute Ma ximum Rat ings” may cause permanen t damage to the devi ce. This is a stress only ra ting and oper ation of th e
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
o
C to 70oC
o
C to 85oC
o
C to 125oC
Maximum Junction Temperature (Plastic Package) . . . . . . . 150
Maximum Storage Temperature Range . . . . . . . . . -65
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300
(SOIC - Lead Tips Only)
NOTES:
1. Due to the SCR structure inherent in the CMOS process used to fabricate these devices, connecting any terminal to a voltage greater than V+
+0.3V or less than V- -0.3V may cause destructive latchup. For this reason it is recommended that no inputs from external sources not operating
from the same power supply be applied to the device before its power supply is established. In multiple supply systems, the supply of the
ICM7555/6 must be turned on first.
is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief 379 for details.
2. θ
JA
Electrical SpecificationsApplies to ICM7555 and ICM7556, Unless Otherwise Specified
Threshold CurrentI
Control VoltageV
Reset VoltageV
ICM7555 VDD = 5V-40200--300µA
DD
V
= 15V-60300--300µA
DD
ICM7556 V
= 10K, C = 0.1µF, VDD = 5V-2---- %
A
= 5V-80400--600µA
DD
= 15V-120600--600µA
V
DD
---858-1161µs
= 5V----150-ppm/oC
V
DD
V
= 10V----200-ppm/oC
DD
V
= 15V----250-ppm/oC
DD
= 5V to 15V-0.5--0.5-%/V
DD
= RB = 10K, C = 0.1µF, VDD = 5V -2---- %
A
---1717-2323µs
= 5V----150-ppm/oC
V
DD
= 10V----200-ppm/oC
V
DD
V
= 15V----250-ppm/oC
DD
= 5V to 15V-0.5--0.5-%/V
DD
VDD = 15V62677161-72% V
TH
= 15V28323627-37% V
VDD = 15V--10--50nA
VDD = 15V--10--50nA
TH
VDD = 15V62677161-72% V
CV
VDD = 2V to 15V0.4-1.00.2-1.2V
RST
(oC/W) θJC (oC/W)
JA
(NOTE 4)
-55oC TO 125oC
o
C to 150oC
UNITSMINTYPMAXMINTYPMAX
o
C
o
C
o
C
DD
DD
DD
2
Page 3
ICM7555, ICM7556
Electrical SpecificationsApplies to ICM7555 and ICM7556, Unless Otherwise Specified
T
A
PARAMETERSYMBOLTEST CONDITIONS
Reset CurrentI
RST
Discharge LeakageI
Output VoltageV
V
Discharge Output VoltageV
Supply Voltage (Note 3)V
Output Rise Time (Note 3)t
Output Fall Time (Note 3)t
Oscillator Frequency
(Note 3)
f
MAX
NOTES:
3. These parameters are based upon characterization data and are not tested.
4. Applies only to military temperature range product (M suffix).
VDD = 15V--10--50nA
VDD = 15V--10--50nA
DIS
VDD = 15V, I
OL
= 5V, I
V
DD
VDD = 15V, I
OH
= 5V, I
V
DD
VDD = 5V, I
DIS
V
= 15V, I
DD
Functional Operation2.0-18.03.0-16.0V
DD
RL = 10M, CL = 10pF, VDD = 5V-75----ns
R
RL = 10M, CL = 10pF, VDD = 5V-75----ns
F
VDD = 5V, RA = 470Ω, RB = 270Ω,
= 20mA-0.41.0--1.25V
SINK
= 3.2mA-0.20.4--0.5V
SINK
SOURCE
SOURCE
SINK
SINK
= 0.8mA14.314.6-14.2--V
= 0.8mA4.04.3-3.8--V
= 15mA-0.20.4--0.6V
= 15mA-----0.4 V
-1----MHz
C = 200pF
= 25oC
(NOTE 4)
-55oC TO 125oC
UNITSMINTYPMAXMINTYPMAX
Functional Diagram
V
DD
8
R
COMPARATOR
THRESHOLD
6
5
CONTROL
VOLTAGE
TRIGGER
2
R
R
GND
A
+
-
+
-
COMPARATOR
B
1
NOTE: This functional diagram reduces the circuitry down to its simplest equivalent components. Tie down unused inputs.
THRESHOLD VOLTAGETRIGGER
VOLTAGERESETOUTPUTDISCHARGE SWITCH
Don’t CareDon’t CareLowLowOn
2
>
/3(V+)>1/3(V+)HighLowOn
2
<
/3(V+)>1/3(V+)HighStableStable
Don’t Care<
1
/3(V+)HighHighOff
FLIP-FLOP
4
RESET
TRUTH TABLE
OUTPUT
DRIVERS
3
7
DISCHARGE
n
1
OUTPUT
NOTE: RESET
will dominate all other inputs: TRIGGER will dominate over THRESHOLD.
3
Page 4
Schematic Diagram
ICM7555, ICM7556
PPP
R
V
P
DD
THRESHOLD
CONTROL
VOLTAGE
TRIGGER
R = 100kΩ ±20% (TYP)
NN
R
R
Application Information
General
The ICM7555/6 devices are, in most instances, direct
replacements for the NE/SE 555/6 devices. However, it is
possible to effect economies in the external component
count using the ICM7555/6. Because the bipolar 555/6
devices produce large crowbar currents in the output driver,
it is necessary to decouple the power supply lines with a
good capacitor close to the device. The 7555/6 devices
produce no such transients. See Figure 1.
500
400
TA = 25oC
NPN
PP
NNNNN
RESETDISCHARGE
The ICM7555/6 produces supply current spikes of only
2mA - 3mA instead of 300mA - 400mA and supply
decoupling is normally not necessary. Also, in most
instances, the CONTROL VOLTAGE decoupling capacitors
are not required since the input impedance of the CMOS
comparators on chip are very high. Thus, for many
applications 2 capacitors can be saved using an ICM7555,
and 3 capacitors with an ICM7556.
POWER SUPPLY CONSIDERATIONS
Although the supply current consumed by the ICM7555/6
devices is very low, the total system supply current can be
high unless the timing components are high impedance.
Therefore, use high values for R and low values for C in
Figures 2 and 3.
OUTPUT
NN
GND
300
SE/NE555
200
100
SUPPLY CURRENT (mA)
0
ICM7555/56
4008006002000
TIME (ns)
FIGURE 1. SUPPLY CURRENT TRANSIENT COMPARED WITH
A STANDARD BIPOLAR 555 DURING AN OUTPUT
TRANSITION
4
OUTPUT
GND
TRIGGER
R
V
DD
RESET
1
2
3
4
FIGURE 2A. ASTABLE OPERATION
V
DD
8
DISCHARGE
7
THRESHOLD
6
5
C
V
DD
10K
CONTROL
VOLTAGE
OPTIONAL
CAPACITOR
ALTERNATE
OUTPUT
Page 5
ICM7555, ICM7556
V
DD
R
A
1
2
OUTPUT
V
DD
FIGURE 2B. ALTERNATE ASTABLE CONFIGURATION
3
4
C
OUTPUT DRIVE CAPABILITY
The output driver consists of a CMOS inverter capable of
driving most logic families including CMOS and TTL. As
such, if driving CMOS, the output swing at all supply
voltages will equal the supply vol t ag e. At a s upp ly vo ltage of
4.5V or more the ICM7555/6 will drive at least 2 standard
TTL loads.
ASTABLE OPERATION
The circuit can be connected to trigger itself and free run as
a multivibrator, see Figure 2A. The output swings from rail to
rail, and is a true 50% duty cycle square wave. (Trip points
and output swings are symmetrical). Less than a 1%
frequency variat ion is obse rved, over a vo ltage range o f +5V
to +15V.
f
The timer can also be connected as shown in Figure 2B. In this
circuit, the frequency is:
f1.44RA2RB+()⁄C=
The duty cycle is controlled by the values of R
equation:
DRARB+()RA2RB+()⁄=
1
------------------=
1.4 RC
8
7
6
R
5
B
OPTIONAL
CAPACITOR
and RB, by the
A
= -ln
(1/3) R
1
2
3
4
C = 1.1RAC
A
ICM7555
OPTIONAL
CAPACITOR
V
DD
8
DISCHARGE
7
THRESHOLD
6
CONTROL
VOLTAGE
5
R
A
C
t
OUTPUT
TRIGGER
OUTPUT
RESET
≤18V
V
DD
FIGURE 3. MONOSTABLE OPERATION
CONTROL VOLTA GE
The CONTROL VOLTAGE terminal permits the two trip
voltages for the THRESHOLD and TRIGGER internal
comparators to be c ont roll ed . Th is pro vi des th e p os si bil ity of
oscillation frequenc y modulation i n the astable mod e or even
inhibition of oscillation, depending on the applied voltage. In
the monostable mode, delay times can be changed by
varying the applied voltag e to the C ONT ROL VOLT AGE pi n.
RESET
The RESET terminal is designed to have essentially the
same trip voltage as the standard bipolar 555/6, i.e., 0.6V to
0.7V. At all supply voltages it represents an extremely high
input impedance. The mode of operation of the RESET
function is, however, much improved over the standard
bipolar 555/6 in that it controls only the internal flip-flop,
which in turn controls simultaneously the state of the
OUTPUT and DISCHARGE pins. This avoids the multiple
threshold problems sometim es encounter ed with sl ow fallin g
edges in the bipolar devices.
MONOSTABLE OPERAT I ON
In this mode of operation, the timer functions as a one-shot, see
Figure 3. Initially the external capacitor (C) is held discharged
by a transistor inside the timer. Upon applicatio n of a negative
TRIGGER
pulse to pin 2, the internal flip-flop is set which
releases the short circuit across the external capacitor and
drives the OUTPUT high. The voltage across the capacitor now
increases exponentially with a time constant t = R
voltage across the capacitor equals
2
/3 V+, the comparator
C. When the
A
resets the flip-flop, which in turn discharge s the capacitor rapidly and also drives the OUTPUT to its low state. TRIGGER
must return to a high state before the OUTPUT can ret urn t o a
low state.
5
Page 6
Typical Performance Curves
ICM7555, ICM7556
1200
TA = 25oC
1100
1000
900
800
700
600
500
400
300
MINIMUM PULSE WIDTH (ns)
200
VDD = 5V
100
0
010203040
LOWEST VOLTAGE LEVEL OF TRIGGER
VDD = 2V
VDD = 18V
PULSE (%VDD)
FIGURE 4. MINIMUM PULSE WIDTH REQUIRED FOR
TRIGGERING
-0.1
TA = 25oC
-1.0
VDD = 2V
VDD = 5V
200
180
160
140
120
100
80
60
40
SUPPLY CURRENT (ICM7555) (µA)
20
0
0 2 4 6 8 1012141618 20
SUPPLY VOLTAGE (V)
TA = -20oC
TA = 25oC
TA = 70oC
FIGURE 5. SUPPLY CURRENT vs SUPPLY VOLTAGE
100
TA = -20oC
10.0
VDD = 18V
VDD = 5V
VDD = 2V
400
360
320
280
240
200
160
120
80
40
0
SUPPLY CURRENT (ICM7556) (µA)
1.0
OUTPUT SINK CURRENT (mA)
0.1
0.010.11.010.0
OUTPUT LOW VOLT A GE (V )
OUTPUT SOURCE CURRENT (mA)
-10.0
-100
VDD = 18V
OUTPUT VOLTAGE REFERENCED TO V
DD
-0.01-0.1-1.0-10
(V)
FIGURE 6. OUTPUT SOURCE CURRENT vs OUTPUT VOLTAGEFIGURE 7. OUTPUT SINK CURRENT vs OUTPUT VOLTAGE
100
TA = 25oC
VDD = 18V
10.0
1.0
OUTPUT SINK CURRENT (mA)
0.1
0.010.11.010.0
OUTPUT LOW VOLTAGE (V)
VDD = 5V
VDD = 2V
100
TA = 70oC
VDD = 18V
10.0
1.0
OUTPUT SINK CURRENT (mA)
0.1
0.010.11.010.0
OUTPUT LOW VOLTAGE (V)
VDD = 5V
VDD = 2V
FIGURE 8. OUTPUT SINK CURRENT vs OUTPUT VOLTAGEFIGURE 9. OUTPUT SINK CURRENT vs OUTPUT VOLTAGE
6
Page 7
Typical Performance Curves (Continued)
8
TA = 25oC
6
4
2
0
RA = RB = 10MΩ
C = 100pF
ICM7555, ICM7556
100
10.0
TA = 25oC
VDD = 18V
VDD = 5V
VDD = 2V
2
4
6
NORMALIZED FREQUENCY DEVIATION (%)
8
0.11.010.0100.0
RA = RB = 10kΩ
C = 0.1µF
SUPPLY VOLTAGE (V)
FIGURE 10. NORMALIZED FREQUENCY STABILITY IN THE
ASTABLE MODE vs SUPPLY VOLTAGE
600
VDD = 5V
500
400
300
200
PROPAGATION DELAY (ns)
100
0
TA = 70oC
TA = 25oC
TA = -20oC
010203040
LOWEST VOLTAGE LEVEL OF TRIGGER
PULSE (%VDD)
FIGURE 12. PROPAGATION DELAY vs VOLTAGE LEVEL OF
TRIGGER PULSE
1.0
DISCHARGE SINK CURRENT (mA)
0.1
0.010.11.010.0
DISCHARGE LOW VOLTAGE (V)
FIGURE 11. DISCHARGE OUTPUT CURRENT vs DISCHARGE
OUTPUT VOLTAGE
+1.0
+0.9
+0.8
+0.7
+0.6
+0.5
+0.4
+0.3
+0.2
+0.1
NORMALIZED FREQUENCY DEVIATION (%)
0
-0.1
RA = RB = 10kΩ
C = 0.1µF
VDD = 5V
VDD = 2V
06080
VDD = 18V
VDD = 2V
4020-20
TEMPERATURE (oC)
FIGURE 13. NORMALIZED FREQUENCY STABILITY IN THE
ASTABLE MODE vs TEMPERATURE
1.0
TA = 25oC
(RA + 2RB)
100.111001K10K 100K1M10M
FREQUENCY (Hz)
CAPACITANCE (F)
100m
10m
1m
100µ
10µ
1µ
100n
10n
1n
100p
10p
1p
FIGURE 14. FREE RUNNING FREQUENCY vs R
7
1kΩ
10kΩ
100kΩ
1MΩ
10MΩ
100MΩ
, RB AND C
A
1.0
1m
1µ
1n
1p
TA = 25oC
100n
1kΩ
10kΩ
100kΩ
1MΩ
10MΩ
100MΩ
10µ
1µ100µ
R
1m10m 100m110
TIME DELAY (s)
A
CAPACITANCE (F)
100m
10m
100µ
10µ
100n
10n
100p
10p
FIGURE 15. TIME DELAY IN THE MONOSTABLE MODE vs
AND C
R
A
Page 8
ICM7555, ICM7556
Small Outline Plastic Packag es (S OIC )
N
INDEX
AREA
123
SEATING PLANE
-AD
e
B
0.25(0.010)C AMBS
E
-B-
A
-C-
M
0.25(0.010)BMM
H
α
µ
A1
0.10(0.004)
L
h x 45
o
C
NOTES:
1. Symbols are defined in the “MO Series Symbol List” in Section 2.2 of
Publication Number 95.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension “D” does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
4. Dimension “E” does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.25mm (0.010 inch) per
side.
5. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
6. “L” is the length of terminal for soldering to a substrate.
7. “N” is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width “B”, as measured 0.36mm (0.014 inch) or greater
above the seating plane, shall not exceed a maximum value of
0.61mm (0.024 inch).
10. Controlling dimension: MILLIMETER. Converted inch dimensions
are not necessarily exact.
1. Index area: A notch or a pin one identification mark shall be located adjacent to pin one and shall be located within t he shaded
area shown. The manufacturer’s identification shall not be used
as a pin one identification mark.
2. The maximum limits of lead dimensions b and c or M shall be
measured at the centroid of the finished lead surfaces, when
solder dip or tin plate lead finish is applied.
3. Dimensions b1 and c1 apply to lead base metal only. Dimension
M applies to lead plating and finish thickness.
4. Corner leads (1, N, N/2, and N/2+1) may be configured with a
partial lead paddle. For this configuration dimension b3 replaces
dimension b2.
5. This dimension allows for off-center lid, meniscus, and glass
overrun.
6. Dimension Q shall be measured from the seating plane to the
base plane.
7. Measure dimension S1 at all four corners.
8. N is the maximum number of terminal positions.
9. Dimensioning and tolerancing per ANSI Y14.5M - 1982.
10. Controlling dimension: INCH.
-DBASE
E
D
S
S
Q
A
-CL
METAL
b1
M
(b)
SECTION A-A
α
(c)
M
eA
eA/2
aaaCA - B
M
c
D
S
S
F14.3 MIL-STD-1835 GDIP1-T14 (D-1, CONFIGURATION A)
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems.
Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without
notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
11
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