IC 555
Hello. Today I want to tell you about the microcircuit 555. Its history began back in 1971, when the company Signetics Corporation launched the SE555 / NE555 microcircuit called The IC Time Machine. In those days, it was the only "timer" chip that was available to the mass consumer. Immediately after the release of 555, it gained widespread popularity and almost all semiconductor manufacturers began to produce it. Domestic manufacturers also released this chip called KR1006VI1 .
The microcircuit is produced in two versions of the case - a plastic DIP and a round metal one. True to meet the 555 in a round metal case in our times is very difficult, can not be said about the version in a plastic DIP package. Inside the case with eight pins, transistors, diodes and resistors are hidden. We will not go into a thorough study of 555, but I will tell you more about the legs of this microcircuit. Total legs 8.
1. Earth . Conclusion, which in all schemes must be connected to the power supply minus.
2. Trigger , it is a launch. If the voltage at the start falls below 1/3 V, then the timer starts. The current consumed by the input does not exceed 500 nA.
3. Exit . The output voltage is approximately 1.7 V below the supply voltage when it is turned on. The maximum load that the output can withstand is 200 mA.
4. Reset . If you apply a low voltage level (less than 0.7 V) to it, then the circuit returns to its original state, regardless of what mode the timer is in at the moment. If the circuit does not need a reset, it is recommended to connect this pin to the power supply.
5. Control . This pin will allow us to access the reference voltage of comparator # 1. This conclusion is used very rarely, and hanging in the air can knock down the work, so in the scheme it is best to attach it to the ground.
6. Threshold , he's stop. If the voltage at this output is higher than 2/3 Vcc, then the timer stops and the output goes to rest. It is worth noting that the output only works when the input is turned off.
7. Discharge . This output connects to the ground inside the microcircuit when the output of the microcircuit is low and closed when the output is high. It can pass up to 200 mA and is sometimes used as an additional output.
8. Power . This output must be connected to the power plus. The microcircuit maintains voltage in the range of 4.5-16 V. It can work from a conventional 9V-battery or from USB wiring.
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Well, it's time to tell you about the 555 chip modes. There are only 3 of them and I will tell you about each in more detail.
When a signal is applied to the input of our microcircuit, it turns on, generates an output pulse of a given length and turns off, waiting for an input pulse. It is important that after turning on the chip will not respond to new signals. The pulse length can be calculated by the formula t = 1.1 * R * C. There are no limits on the duration of the pulses, both in the minimum and in the maximum duration. There are some practical limitations that can be circumvented, but it is worth considering whether this is necessary and whether it is not easier to choose another solution. So, the minimum values established in a practical way for R is 10 kOhm, and for C - 95pF. It is possible and less, but at the same time the scheme will begin to absorb a lot of electricity.
In this mode, everything is pretty simple. You do not need to control the timer. He will do everything himself - he will turn on first, wait for t1, then turn off, wait for t2 and start all over again. At the exit we get a fence of high and low states. The frequency with which will fluctuate depends on the parameters of the values of R1, R2 and C and is determined by the formula F = 1.44 / ((R1 + R2) C). During the time t1 = 0.693 (R1 + R2) C the output will be high, and during the time 2 = 0.693R2C it will be low.
In this mode, our chip 555 is used as a switch. I pressed one button - the output turned on, pressed another - turned off.
I think you are already tired of the theoretical material and you want to start the practice. You can buy the microchip itself and the details to it in any radio shop. Well, if you are too lazy to go to the store, you can order all the details on this site . I forgot to say that the parcel will go to you for about a month. Thank you for your attention, if you liked my article, then later I will definitely write another one, where I will tell you which gadgets can be made on a 555 chip.
What is this miracle?
The microcircuit is produced in two versions of the case - a plastic DIP and a round metal one. True to meet the 555 in a round metal case in our times is very difficult, can not be said about the version in a plastic DIP package. Inside the case with eight pins, transistors, diodes and resistors are hidden. We will not go into a thorough study of 555, but I will tell you more about the legs of this microcircuit. Total legs 8.
1. Earth . Conclusion, which in all schemes must be connected to the power supply minus.
2. Trigger , it is a launch. If the voltage at the start falls below 1/3 V, then the timer starts. The current consumed by the input does not exceed 500 nA.
3. Exit . The output voltage is approximately 1.7 V below the supply voltage when it is turned on. The maximum load that the output can withstand is 200 mA.
4. Reset . If you apply a low voltage level (less than 0.7 V) to it, then the circuit returns to its original state, regardless of what mode the timer is in at the moment. If the circuit does not need a reset, it is recommended to connect this pin to the power supply.
5. Control . This pin will allow us to access the reference voltage of comparator # 1. This conclusion is used very rarely, and hanging in the air can knock down the work, so in the scheme it is best to attach it to the ground.
6. Threshold , he's stop. If the voltage at this output is higher than 2/3 Vcc, then the timer stops and the output goes to rest. It is worth noting that the output only works when the input is turned off.
7. Discharge . This output connects to the ground inside the microcircuit when the output of the microcircuit is low and closed when the output is high. It can pass up to 200 mA and is sometimes used as an additional output.
8. Power . This output must be connected to the power plus. The microcircuit maintains voltage in the range of 4.5-16 V. It can work from a conventional 9V-battery or from USB wiring.
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Modes
Well, it's time to tell you about the 555 chip modes. There are only 3 of them and I will tell you about each in more detail.
Monostable
When a signal is applied to the input of our microcircuit, it turns on, generates an output pulse of a given length and turns off, waiting for an input pulse. It is important that after turning on the chip will not respond to new signals. The pulse length can be calculated by the formula t = 1.1 * R * C. There are no limits on the duration of the pulses, both in the minimum and in the maximum duration. There are some practical limitations that can be circumvented, but it is worth considering whether this is necessary and whether it is not easier to choose another solution. So, the minimum values established in a practical way for R is 10 kOhm, and for C - 95pF. It is possible and less, but at the same time the scheme will begin to absorb a lot of electricity.
Unstable Multivibrator
In this mode, everything is pretty simple. You do not need to control the timer. He will do everything himself - he will turn on first, wait for t1, then turn off, wait for t2 and start all over again. At the exit we get a fence of high and low states. The frequency with which will fluctuate depends on the parameters of the values of R1, R2 and C and is determined by the formula F = 1.44 / ((R1 + R2) C). During the time t1 = 0.693 (R1 + R2) C the output will be high, and during the time 2 = 0.693R2C it will be low.
Bistable
In this mode, our chip 555 is used as a switch. I pressed one button - the output turned on, pressed another - turned off.
the end
I think you are already tired of the theoretical material and you want to start the practice. You can buy the microchip itself and the details to it in any radio shop. Well, if you are too lazy to go to the store, you can order all the details on this site . I forgot to say that the parcel will go to you for about a month. Thank you for your attention, if you liked my article, then later I will definitely write another one, where I will tell you which gadgets can be made on a 555 chip.
Source: https://habr.com/ru/post/119681/
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