®
ICM7555, ICM7556
Data Sheet
August 24, 2006
FN2867.9
General Purpose Timers
The ICM7555 and ICM7556 are CMOS RC timers providing
significantly improved performance over the standard
SE/NE 555/6 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 SE/NE 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 sink
currents large enough to drive TTL loads, or provide minimal
offsets to drive CMOS loads.
Features
• Exact Equivalent in Most Cases for SE/NE555/556 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 555/6 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, HI and LO
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• Precision Timing
• Pulse Generation
• Sequential Timing
• Time Delay Generation
• Pulse Width Modulation
• Pulse Position Modulation
• Missing Pulse Detector
Pinouts
ICM7555 (8 LD PDIP, SOIC)
TOP VIEW
ICM7556 (14 LD PDIP, CERDIP)
TOP VIEW
DISCHARGE 1
GND 1
TRIGGER 2
OUTPUT 3
RESET 4
8 V
DD
7 DISCHARGE
6 THRESHOLD
5 CONTROL
VOLTAGE
THRESH- 2
OLD
CONTROL 3
VOLTAGE
RESET 4
OUTPUT 5
TRIGGER 6
GND 7
14 V
DD
13 DISCHARGE
12 THRESHOLD
11
CONTROL
VOLTAGE
10 RESET
9 OUTPUT
8 TRIGGER
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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