Clock & Timer ICs Distributor

What is Clock & Timer ICs?

The 555 timer IC is an integrated circuit chip used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide two 556 or four 558 timing circuits in one package. Introduced in 1972 by Signetics, the 555 is still in widespread use due to its low price, ease of use, and stability. It is now made by many companies in the original bipolar and in low-power CMOS technologies. As of 2003, it was estimated that 1 billion units were manufactured every year. The 555 is the most popular integrated circuit ever manufactured. Depending on the manufacturer, the standard 555 package includes 25 transistors, 2 diodes and 15 resistors on a silicon chip installed in an 8-pin dual in-line package (DIP-8).[Variants available include the 556 a DIP-14 combining two complete 555s on one chip, and 558 / 559 both a DIP-16 combining four reduced-functionality timers on one chip. The NE555 parts were commercial temperature range, 0C to +70C, and the SE555 part number designated the military temperature range, -55C to +125C. These were available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and SE555T. Low-power CMOS versions of the 555 are also available, such as the Intersil ICM7555 and Texas Instruments LMC555, TLC555, TLC551. CMOS timers use significantly less power than bipolar timers; CMOS timers also cause less supply noise than bipolar version when the output switches states. The ICM7555 datasheet claims that it usually doesn't require a "control" capacitor and in many cases does not require a decoupling capacitor across the power supply pins. A decoupling capacitor reduces noise or variation in power supply voltage that may affect other parts of a circuit or affect the timer's threshold voltages.