The LM555 timer is a very stable timer device that generates accurate time delays and oscillations. In the time delay mode, it functions so that an external resistor and capacitor controls time, particularly during the Oscillation state, two external resistors and one capacitor control the free-running frequency and duty cycle.
This LM555 timer has replaced SE555 and NE555, and it comes in a package of an 8-pin IPDIP, SOIC and VSSOP.
LM555 Datasheet
According to its datasheet, some of the main specs of the chip are:
- It requires a voltage supply within 4.5v to 16v
- Its trigger voltage is 1.67 in parallel with +5V
- The minimum recommended capacitor value is 0.1μF
- The minimum recommended electrolytic capacitor is 1-μF
- The Source current of the output is 200mA
- It has an operating temperature of 70 degrees celsius.
- It has limited built-in ESD protection.
The following are the key application areas for the chip:
- Sequential Timing circuits
- Time delay generation
- Precision Timing
- Pulse Generation
- Pulse width moderation
LM555 pinout
The LM555 timer is an 8-pin IC. Meaning it has eight different pins with different functions for the IC. It also has three resistors of 5K value hence the name 555. Furthermore, its dual comparators and flip-flop enable it to operate in Astable, Monostable and Bistable mode.
The trigger pin is pin 8, and when the voltage at the pin falls below half of the control voltage, the interval starts and the output reaches a high state.
You can see the lm555 chip pinout diagram image below.
LM555 Equivalents and Replacement Details
The chip uses logic clocks, lamp flashers. The security alarms during the free-running mode use a circuit based on microprocessors to convert the pulse period to temperature and provide a means of calibration. The LM555 timer IC equivalents are LM556, SE555and NE556.
