1
DATASHEET
General Purpose Timers
ICM7555, ICM7556
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.
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)
TOP VIEW
ICM7556
(14 LD PDIP, CERDIP)
TOP VIEW
GND
TRIGGER
OUTPUT
RESET
1
2
3
4
8
7
6
5
V
DD
DISCHARGE
THRESHOLD
CONTROL
VOLTAGE
DISCHARGE1
CONTROL
RESET1
OUTPUT1
TRIGGER1
GND
V
DD
DISCHARGE2
THRESHOLD2
CONTROL
RESET2
OUTPUT2
TRIGGER2
1
2
3
4
5
6
7
14
13
12
11
10
9
8
VOLTAGE2
VOLTAGE1
THRESHOLD1
June 28, 2016
FN2867.10
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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