DATASHEET
ICM7555, ICM7556
General Purpose Timers
The
ICM7555
and
ICM7556
are CMOS RC timers providing
significantly improved performance over the standard
SE/NE 555/556 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
SE/NE 555/556 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 sink currents large enough to drive TTL loads, or
provide minimal offsets to drive CMOS loads.
FN2867
Rev 1.00
June 28, 2016
Features
• Exact equivalent in most cases for SE/NE 555/556 or
TLC555/556
• Low supply current
- ICM7555 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60µA
- ICM7556 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120µA
• Extremely low input currents . . . . . . . . . . . . . . . . . . . . . . 20pA
• High speed operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1MHz
• Guaranteed supply voltage range . . . . . . . . . . . . . . 2V to 18V
• Temperature stability . . . . . . . . . . . . . 0.005%/°C at +25°C
• Normal reset function - no crowbarring of supply during
output transition
• Can be used with higher impedance timing elements than
regular 555/556 for longer RC time constants
• Timing from microseconds through hours
• Operates in both astable and monostable modes
• Adjustable duty cycle
• High output source/sink driver can drive TTL/CMOS
• Outputs have very low offsets, HIGH and LOW
• Pb-free (RoHS Compliant)
Applications
• Precision timing
• Pulse generation
• Sequential timing
• Time delay generation
• Pulse width modulation
• Pulse position modulation
• Missing pulse detector
Pin Configurations
ICM7555
(8 LD PDIP, SOIC)
ICM7556
(14 LD PDIP, CERDIP)
TOP VIEW
DISCHARGE1 1
GND 1
TRIGGER 2
OUTPUT 3
RESET 4
8 V
DD
7 DISCHARGE
6 THRESHOLD
5 CONTROL
VOLTAGE
THRESHOLD1 2
CONTROL 3
VOLTAGE1
RESET1 4
OUTPUT1 5
TRIGGER1 6
GND 7
TOP VIEW
14 V
DD
13 DISCHARGE2
12 THRESHOLD2
11 CONTROL
VOLTAGE2
10 RESET2
9 OUTPUT2
8 TRIGGER2
FN2867 Rev 1.00
June 28, 2016
Page 1 of 13
ICM7555, ICM7556
Ordering Information
PART NUMBER
ICM7555CBAZ (Notes
2, 3)
ICM7555CBAZ-T (Notes
1, 2, 3)
ICM7555IBAZ (Notes
2, 3)
ICM7555IBAZ-T (Notes
1, 2, 3)
ICM7555IPAZ (Notes
2, 3)
ICM7556IPDZ (Notes
2, 3)
PART MARKING
7555 CBAZ
7555 CBAZ
7555 IBAZ
7555 IBAZ
7555 IPAZ
ICM7556IPDZ
TEMP. RANGE
(°C)
0 to +70
0 to +70
-25 to +85
-25 to +85
-25 to +85
-25 to +85
-55 to +125
2.5k
2.5k
TAPE AND REEL
(UNITS)
PACKAGE
(RoHS COMPLIANT)
8 Ld SOIC
PKG. DWG. #
M8.15
8 Ld SOIC (Tape and Reel) M8.15
8 Ld SOIC
M8.15
8 Ld SOIC (Tape and Reel) M8.15
8 Ld PDIP
14 Ld PDIP
14 Ld Cerdip
E8.3
E14.3
F14.3
ICM7556MJD
ICM7556MJD
(No longer available or supported)
NOTES:
1. Please refer to
TB347
for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is 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.
3. For Moisture Sensitivity Level (MSL), please see product information page for
ICM7555, ICM7556.
For more information on MSL, please see tech brief
TB363.
FN2867 Rev 1.00
June 28, 2016
Page 2 of 13
ICM7555, ICM7556
Absolute Maximum Ratings
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +18V
Input Voltage
Trigger, Control Voltage, Threshold,
Reset (Note
4)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . V+ +0.3V to GND -0.3V
Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100mA
Thermal Information
Thermal Resistance (Typical,
Notes 5, 6)
JA
(°C/W)
JC
(°C/W)
14 Ld CERDIP Package . . . . . . . . . . . . . . .
80
24
14 Ld PDIP Package* . . . . . . . . . . . . . . . .
115
46
8 Ld PDIP Package* . . . . . . . . . . . . . . . . .
130
69
8 Ld SOIC Package. . . . . . . . . . . . . . . . . . .
170
67
Maximum Junction Temperature (Hermetic Package) . . . . . . . . . . . .+175°C
Maximum Junction Temperature (Plastic Package) . . . . . . . . . . . .+150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . -65°C to +150°C
* 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
ICM7555C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
ICM7555I, ICM7556I . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25°C to +85°C
ICM7556M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-55°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. 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 latch-up. 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 and
ICM7556 must be turned on first.
5.
JA
is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief
TB379
for details.
6. For
JC
, the “case temp” location is taken at the package top center.
Electrical Specifications
Applies to ICM7555 and ICM7556, unless otherwise specified.
T
A
= +25°C
(Note
8)
-55°C TO+125°C
MAX
200
300
400
600
MIN
TYP
MAX
300
300
600
600
UNIT
µA
µA
µA
µA
%
858
1161
150
200
250
0.5
2
1717
2323
150
200
250
0.5
62
28
67
32
71
36
10
10
62
67
71
61
61
27
0.5
72
37
50
50
72
0.5
µs
ppm/°C
ppm/°C
ppm/°C
%/V
%
µs
ppm/°C
ppm/°C
ppm/°C
%/V
% V
DD
% V
DD
nA
nA
% V
DD
PARAMETER
Static Supply Current
SYMBOL
I
DD
ICM7555
TEST CONDITIONS
V
DD
= 5V
V
DD
= 15V
ICM7556
V
DD
= 5V
V
DD
= 15V
MIN
TYP
40
60
80
120
2
Monostable Timing Accuracy
R
A
= 10k, C = 0.1µF, V
DD
= 5V
Drift with Temperature
(Note
7)
V
DD
= 5V
V
DD
= 10V
V
DD
= 15V
Drift with Supply (Note
7)
Astable Timing Accuracy
V
DD
= 5V to 15V
R
A
= R
B
= 10k, C = 0.1µF, V
DD
= 5V
Drift with Temperature
(Note
7)
V
DD
= 5V
V
DD
= 10V
V
DD
= 15V
Drift with Supply (Note
7)
Threshold Voltage
Trigger Voltage
Trigger Current
Threshold Current
Control Voltage
V
TH
V
TRIG
I
TRIG
I
TH
V
CV
V
DD
= 5V to 15V
V
DD
= 15V
V
DD
= 15V
V
DD
= 15V
V
DD
= 15V
V
DD
= 15V
FN2867 Rev 1.00
June 28, 2016
Page 3 of 13
ICM7555, ICM7556
Electrical Specifications
Applies to ICM7555 and ICM7556, unless otherwise specified. (Continued)
T
A
= +25°C
(Note
8)
-55°C TO+125°C
MAX
1.0
10
10
0.4
0.2
14.3
4.0
14.6
4.3
0.2
0.4
1.0
0.4
14.2
3.8
0.6
0.4
2.0
75
75
1
18.0
3.0
16.0
MIN
0.2
TYP
MAX
1.2
50
50
1.25
0.5
UNIT
V
nA
nA
V
V
V
V
V
V
V
ns
ns
MHz
PARAMETER
Reset Voltage
Reset Current
Discharge Leakage
Output Voltage
SYMBOL
V
RST
I
RST
I
DIS
V
OL
TEST CONDITIONS
V
DD
= 2V to 15V
V
DD
= 15V
V
DD
= 15V
V
DD
= 15V, I
SINK
= 20mA
V
DD
= 5V, I
SINK
= 3.2mA
MIN
0.4
TYP
V
OH
V
DD
= 15V, I
SOURCE
= 0.8mA
V
DD
= 5V, I
SOURCE
= 0.8mA
Discharge Output Voltage
V
DIS
V
DD
= 5V, I
SINK
= 15mA
V
DD
= 15V, I
SINK
= 15mA
Supply Voltage (Note
7)
Output Rise Time (Note
7)
Output Fall Time (Note
7)
Oscillator Frequency
(Note
7)
NOTES:
V
DD
t
R
t
F
f
MAX
Functional Operation
R
L
= 10M, C
L
= 10pF, V
DD
= 5V
R
L
= 10M, C
L
= 10pF, V
DD
= 5V
V
DD
= 5V, R
A
= 470Ω, R
B
= 270Ω,
C = 200pF
7. These parameters are based upon characterization data and are not tested.
8. Applies only to military temperature range product (M suffix).
Functional Diagram
V
DD
8
R
THRESHOLD
6
5
CONTROL
VOLTAGE
R
+
COMPARATOR
A
+
4
FLIP-FLOP
RESET
OUTPUT
DRIVERS
-
7
n
1
3
OUTPUT
DISCHARGE
TRIGGER
2
R
-
COMPARATOR
B
1
GND
NOTE: This functional diagram reduces the circuitry down to its simplest equivalent components. Tie down unused inputs.
FIGURE 1. FUNCTIONAL DIAGRAM
TRUTH TABLE
THRESHOLD VOLTAGE
Don’t Care
>
2
/
3
(V+)
<
2
/
3
(V+)
Don’t Care
TRIGGER VOLTAGE
Don’t Care
>
1
/
3
(V+)
>
1
/
3
(V+)
<
1
/
3
(V+)
RESET
Low
High
High
High
OUTPUT
Low
Low
Stable
High
DISCHARGE SWITCH
On
On
Stable
Off
NOTE: RESET will dominate all other inputs: TRIGGER will dominate over THRESHOLD.
FN2867 Rev 1.00
June 28, 2016
Page 4 of 13
ICM7555, ICM7556
Schematic Diagram
P
P
R
P
P
V
DD
THRESHOLD
N
CONTROL
VOLTAGE
N
R
NPN
OUTPUT
P
P
TRIGGER
R
N
N
N
N
N
N
N
GND
RESET
R = 100kΩ
±20%
(TYP)
DISCHARGE
FIGURE 2. SCHEMATIC DIAGRAM
Application Information
General
The ICM7555 and ICM7556 devices are, in most instances,
direct replacements for the SE/NE 555/556 devices. However,
it is possible to effect economies in the external component
count using the ICM7555 and ICM7556. Because the bipolar
SE/NE 555/556 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 ICM7555
and ICM7556 devices produce no such transients (see
Figure 3).
500
T
A
= +25°C
SUPPLY CURRENT (mA)
400
300
SE/NE 555
The ICM7555 and ICM7556 produce supply current spikes of
only 2mA to 3mA instead of 300mA to 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, two capacitors can
be saved using an ICM7555 and three capacitors with an
ICM7556.
POWER SUPPLY CONSIDERATIONS
Although the supply current consumed by the ICM7555 and
ICM7556 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 4, 5,
and
6.
V
DD
GND
TRIGGER
OUTPUT
1
2
3
4
RESET
8
7
6
5
V
DD
DISCHARGE
THRESHOLD
CONTROL
VOLTAGE
OPTIONAL
CAPACITOR
10k
ALTERNATE OUTPUT
200
100
0
ICM7555/556
0
200
400
TIME (ns)
600
800
V
DD
R
C
FIGURE 4. ASTABLE OPERATION
FIGURE 3. SUPPLY CURRENT TRANSIENT COMPARED WITH A
STANDARD BIPOLAR 555 DURING AN OUTPUT
TRANSITION
FN2867 Rev 1.00
June 28, 2016
Page 5 of 13
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