DATASHEET
General Purpose Timers
ICM7555, ICM7556
Features
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.
• Exact equivalent in most cases for SE/NE 555/556 or
TLC555/556
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.
• 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
TOP VIEW
DISCHARGE1 1
GND 1
8 VDD
TRIGGER 2
7 DISCHARGE
OUTPUT 3
6 THRESHOLD
5 CONTROL
VOLTAGE
RESET 4
14 VDD
THRESHOLD1 2
13 DISCHARGE2
CONTROL 3
VOLTAGE1
12 THRESHOLD2
RESET1 4
OUTPUT1 5
TRIGGER1 6
GND 7
June 28, 2016
FN2867.10
1
11 CONTROL
VOLTAGE2
10 RESET2
9 OUTPUT2
8 TRIGGER2
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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