TABLE OF CONTENTS IC NE/SE 555 is a highly stable device for generating accurate time delays. Commercially, this IC is available in 8-pin circular, TO-99 or 8-pin DIP, or 14-pin DIP packages.
The salient features of 555 timer ICs are
Compatible with both TTL and CMOS logic families.
The maximum load current can go up to 200 mA.
The typical power supply voltage is from + 5 V to + 18 V.
It can be used in a variety of applications such as oscillators, pulse generators, ramp generators, square wave generators, monoshot multivibrator burgular alarms, and traffic light controls.
The pin diagram of an 8-pin DIP 555 timer IC is given in Figure 6.1.
The simplified form of internal diagram of IC 555 is shown in Figure 6.2. IC 555 consists of two comparators, a lower comparator and an upper comparator. It consists of a potential divider containing three 5 k ? resistors and an RS flip flop, where the R input is connected to the upper comparator and the lower comparator output is the S input.
The connection diagram for monostable operation using IC 555 is shown in Figure 6.3. Pin 5 is connected to the ground through 0.01 ?F, to keep pin 5 inactive, i.e., the internal potential divider takes care of everything and no external modulation voltage is applied. Pin 4 is connected to...
