The 555 consists of bipolar transistors, resistors, and diodes. These are reduced function versions of the 555, with some pins missing. 558 – A quad version, in a 16-pin package.All the 555 pins are available for both timers. 556 – A dual 555 timer, in a 14-pin package.In addition to the CMOS versions, there are two additional variations of the 555 timer IC: There are also low-power CMOS versions of the 555, such as the IN555, TS555, and LMC555. The 555 can operate with any voltage between 4.5 and 16 volts DC, and can sink or source up to 200mA. The pinouts for the 555 are shown in the above illustration.

The 555 timer is packaged in an 8-pin DIP (dual inline package), it is also available in surface mount versions. We’ll also put together five small 555-based projects. Today we will look at what makes this timer tick, and we’ll experiment with the three different modes you can operate it in. This makes the 555 one of the most popular integrated circuits ever produced. Because of its versatility, the 555 has been used in hundreds of thousands of designs, and currently, approximately a billion of these chips are sold every year.

Free download 555 timer pinout