Microcircuit 555: application

IC integrated timer NE555 - this is a real breakthrough in the field of electronics. It was created in 1972 by the employee of Signetics company Hans R. Kamenzind. The invention has not lost its relevance to this day. Later, the device became the basis of timers with a doubled (IN556N) and quad configuration (IN558N).

No doubt, the brainchild of the electronics engineer allowed him to occupy his prominent niche in the history of technical inventions. In terms of sales, this device has surpassed any other since its inception. In the second year of its existence, the 555 chip became the most purchased part.

Leadership persisted in all subsequent years. The 555 chip, the use of which grew every year, sold very well. For example, in 2003, more than 1 billion copies were sold. The configuration of the unit itself has not changed during this time. It exists over 40 years.

The appearance of the device was a surprise for the creator. Kamenzind pursued the goal of making it flexible in the use of IP, but that it would prove so multifunctional, he did not expect. Initially, it was used as a timer or pulse generator. Chip 555, the application of which has increased rapidly, is now used from toys for children to spacecraft.

The device features endurance, because it is built on the basis of bipolar technology, and nothing is required to apply it specifically to space. Only test work is carried out with extreme severity. Thus, with the test scheme NE 555 for a number of applications, individual test specifications are created. In the production of schemes, there are no differences, but approaches differ significantly with the output control.

The appearance of the circuit in domestic electronics

The first mention of innovation in the Soviet literature on radio engineering appeared in 1975. The article about the invention was published in the journal "Electronics". The microcircuit 555, analogue of which was created by Soviet electronics engineers in the late 80s of the last century, was named KR1006VI1 in Russian radio electronics.

In production, this part was used in the assembly of VCR Electronics Electronics VM12. But it was not the only analog, as many manufacturers around the world have created such a device. All units have a durable housing DIP8, as well as a small body SOIC8.

Technical characteristics of the circuit

The chip 555, the graphic representation of which is presented below, includes 20 transistors. On the block diagram of the device there are 3 resistors with a resistance of 5 kOhm. Hence the name of the device "555".

The main technical characteristics of the product are:

• Power supply voltage is 4.5-18V;
• The maximum output current of 200 mA;
• The consumed energy is up to 206 mA.

If you look at it, it's a digital device. It can be in two positions - low (0V) and high (4.5 to 15V). Depending on the power supply, the indicator can reach 18 V.

Why do I need a device?

NE 555 chip - a unified device with a wide range of applications. It is often used in the assembly of various schemes, and this only gives the product popularity. Accordingly, the level of consumer demand is increasing. Such fame caused a drop in the price of the timer, which pleases many masters.

The internal structure of the 555 timer

What makes this device function? Each of the terminals of the unit is connected to a circuit containing 20 transistors, 2 diodes and 15 resistors.

Dual format of the model

It should be noted that the NE 555 (microchip) is available in a doubled format called the 556. It contains two free ICs.

Timer 555 is equipped with 8 contacts, while model 556 contains 14 contacts.

Modes of operation of the device

The 555 has three modes of operation:

1. Monostable mode of the chip 555. It works as a one-way one-sided. During operation, a pulse of a predetermined length is ejected as a response to the trigger input when the button is pressed. The output is in low voltage until the trigger is turned on. Hence he was called waiting (monostable). Such a functioning principle keeps the device idle before it is turned on. The mode provides the inclusion of timers, switches, touch switches, frequency dividers, etc.
2. Unstable mode is an autonomous function of the device. It allows the circuit to stay in generator mode. The voltage in the output is variable: then low, then high. This scheme is applicable if you need to set the device jerks intermittent in nature (with the short-term activation and shutdown of the unit). The mode is used when the lamps are switched on with LEDs, it functions in the logic scheme of the clock, etc.
3. Bistable mode, or Schmidt trigger. It is clear that it operates on a trigger system in the absence of a capacitor and has two stable states, high and low. The low value of the trigger goes to high. When the low voltage is dropped, the system rushes to a low state. This scheme is applicable in the field of railway construction.

Timer outputs 555

The chip generator 555 includes eight outputs:

1. Conclusion 1 (earth). It is connected to the negative side of the power (common circuit wire).
2. Output 2 (trigger). It supplies high voltage for a while (all depends on the power of the resistor and the capacitor). This configuration is monostable. Pin 2 controls pin 6. If the voltage in both is low, then it will be high at the output. Otherwise, at a high voltage in pin 6 and low in pin 2, the output on the timer will be low.
3. Output 3 (output). Outputs 3 and 7 are in phase. Supplying a high voltage with a value of about 2 V and a low voltage from 0.5 V will result in up to 200 mA.
4. Output 4 (reset). The voltage supply to this output is low, despite the operating mode of the 555. To avoid accidental discharges, you must connect this output to the positive side when using.
5. Conclusion 5 (control). It opens access to the comparator voltage. This conclusion does not apply to Russian electronics, but when it is connected, you can achieve a wide range of control options for the 555 device.
6. Output 6 (stop). It is included in comparator 1. It is opposite to pin 2, it is applicable to stop the device. This results in a low voltage. This pin can take sinusoidal and rectangular pulses.
7. Conclusion 7 (digit). It is connected to the transistor collector T6, and the emitter of the latter is grounded. When the transistor is open, the capacitor is discharged until it is closed.
8. Conclusion 8 (plus side of power supply), which is from 4.5 to 18 V.

Using the Output Output

Output 3 (Output) can be in two states:

1. A digital output is connected directly to the input of another driver on a digital basis. The digital output can control other devices by means of several additional components (the voltage of the power supply is 0 V).
2. The voltage reading in the second state is high (Vcc on the power supply).

Unit Features

1. When the voltage is lowered to the Output, the current is routed through the device and connects it. This is a reduction, since the current is produced from Vcc and passes through the unit to 0 V.
2. As the Output increases, the current passing through the instrument ensures its activation. This process can be called a source of current. Electricity in this case is made from a timer and goes through the device to 0 V.

The rise and fall can function together. In this way, the device turns on and off one by one. This principle is applicable to the operation of lamps on LEDs, relays, motors, electromagnets. The disadvantages of this feature include the fact that the device must be connected to Output in various ways, since output 3 can act both as a consumer and as a current source up to 200 mA. The power supply used must be set to supply sufficient current for both devices and a timer 555.

LM555 chip

Microcircuit 555 DataLight (LM555) has a wide functionality.

It is used from rectangular pulse generators with variable duty cycle and relay and delay times to complex PWM generator configurations. Microcircuit 555 pin and internal structure are reflected in the figure.

The level of accuracy of the device is 1% of the calculated index, which is optimal. On such an aggregate as NE 555 the chip is datasheet, the ambient temperature conditions are not affected.

Analogues of chip NE555

The 555 chip, the analogue of which in Russia was called KR1006VI1, represents an integrated device.

Among the working blocks, one should distinguish the RS-trigger (DD1), the comparators (DA1 and DA2), the output amplifier stage based on the push-pull system and the VT3 transistor. The purpose of the latter is to reset the time-controlling capacitor when using the unit as a generator. Trigger reset occurs when a logical unit (Jupit / 2 ... Jupit) is applied to the inputs R.

If the trigger is reset, the output of the device (pin 3) will have a low voltage (the transistor VT2 is open).

The uniqueness of the scheme 555

When the functional diagram of the device is very difficult to understand what is its unusualness. The originality of the device is that it has a special control of the trigger, namely, it generates control signals. Their creation occurs on the comparators DA1 and DA2 (one of the inputs to which the reference voltage is applied). To generate control signals at the inputs of the trigger (outputs of comparators), signals with a high voltage should be received.

How do I start the device?

To start the timer, output 2 must be supplied with a voltage from 0 to 1/3 Jupiter. This signal facilitates the triggering of the trigger, and at the output a high voltage signal is generated. A signal above the limit does not cause any changes in the circuit, since the reference voltage for the comparator is DA2 and is 1/3 Jupiter.

You can stop the timer when you reset the trigger. For this purpose, the voltage at the output 6 should exceed the indicator 2/3 Jupiter (the reference voltage for the comparator DA1 is 2/3 Jupiter). When reset, a low voltage signal is set and a capacitor that sets the time is discharged.

The reference voltage can be adjusted by connecting an additional resistance or power supply to the unit terminal.

Winding of a speedometer on 555 microcircuit

Recently, among car owners, it has become fashionable to wind up a mileage on the speedometer.

Many people are wondering whether the speedometer rewind on the 555 chip is self-executing?

This procedure is not particularly difficult. To make it, a chip 555 is used, which can function as a pulse counter. Individual components of the scheme can be taken with indicators deviating by 10-15% of the calculated values.