1

®

FN2867.9

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

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ICM7555, ICM7556

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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

μA

- ICM7556 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

μA

• 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

GND

TRIGGER

OUTPUT

RESET

1

2

3

4

8

7

6

5

DISCHARGE

THRESHOLD

CONTROL

VOLTAGE

DISCHARGE

THRESH-

CONTROL

RESET

OUTPUT

TRIGGER

GND

DISCHARGE

THRESHOLD

CONTROL

RESET

OUTPUT

TRIGGER

1

2

3

4

5

6

7

14

13

12

11

10

9

8

VOLTAGE

VOLTAGE

OLD

Data Sheet

August 24, 2006