There are many types of integrated circuits, different functions, pin arrangements and shapes, and there are various products such as domestic, imported, and joint ventures. Therefore, the following aspects should be paid attention to when selecting.
①Select according to circuit requirements. All kinds of products are composed of different circuits, and the functions and requirements of each part of the circuit are different. For example, the circuit, whether to choose a series type or a switch type, what is the output voltage, and what is the input voltage are all considerations when choosing.
② When selecting an integrated circuit, it is necessary to understand the performance of the selected integrated circuit, because the parameters of different types of integrated circuits are different. If you are not sure, you should consult relevant information. In short, before installing the integrated circuit into the circuit, it is necessary to fully understand the functions, parameters, pin functions and arrangement rules of the integrated circuit.
③ For integrated circuits with the same function but different packaging, it should be determined according to the conditions of use.
④ For circuits with high requirements, integrated circuits with high parameter indicators can be selected, and for circuits with low requirements for various indicators, it is not necessary to choose products with high indicators.
1. Three-terminal regulator integrated circuit
Optional models are lm317 series, w78 series, w79 series, etc. Three-terminal voltage regulator integrated circuits are divided into fixed output voltage (w7800, w7900) and adjustable (lm317), and can be divided into two categories: positive output voltage and negative output voltage. The output voltage of the w78 series (positive output) voltage regulator circuit is divided into seven grades: 5v, 6v, 9v, 12v, 15v, 18v, and 24v; the maximum output current is 1.5a, 0.5a, 0.1a. Negative output voltage The output current and output voltage of the w79 series are the same as those of the w78 series, and they are mainly used in DC regulated power supply circuits to stabilize voltage.
2. integrated operational amplifier
①Cf741 corresponds to foreign lm741, μa741, mc741 and other models. It is one of the most common integrated operational amplifiers at present, with high gain, wide input voltage range of common mode and differential mode, non-blocking, low power consumption, and output short-circuit protection , No need for external frequency compensation, etc., but its frequency characteristics are poor, so it is only used in occasions that do not require high amplifier bandwidth.
② The cf747 double operational amplifier circuit is the same as the foreign lm747, μa747, mc747 circuit. It is composed of two single operational amplifiers, and has the same advantages and characteristics as the cf741.
③ The cf324 single-supply operational amplifier is the same as the foreign lm324 and μa324 circuits. It consists of 4 independent and identical performance operational amplifiers with low power consumption, high gain, and compensation within the frequency. Work under 3~30v single power supply or ±1.5~±15v dual power supply.
④ The cf353 high-speed dual operational amplifier is the same as the foreign lf353 circuit. It has the characteristics of small input bias current, small input offset current, gain bandwidth, high input resistance, fast conversion speed, and low noise.
The integrated operational amplifier breaks the design method of discrete components and discrete circuits, and realizes the unification of materials, components and circuits. Mainly used for signal calculation (proportion, addition, subtraction, integral, differential operation), signal processing (active filter, sample and hold circuit, voltage comparator), waveform generation (rectangular wave generator, triangular wave generator, sawtooth wave generation) device), signal measurement (automatic control and non-electricity measurement), etc.
Pay attention during use: it must be cleared before use; ensure that the DC resistances of the external circuits at the two input terminals are equal to prevent the output from deviating from zero; the input and output leads should not cross, and the ground wires should be routed so that the currents of all levels are free into a loop; in order to avoid self-oscillation, a parallel resistive capacitor device is connected between the output terminal and the inverting input terminal; in order to avoid damage to the input stage of the operational amplifier due to excessive signal amplitude, two reverse limiters are connected in parallel at the input terminal Width protection circuit.
3. integrated power amplifier
① Classification: According to the size of the input power, it is divided into small, medium and high power amplifiers, and the output power ranges from hundreds of milliwatts to tens of watts. According to the internal circuit, it is divided into a power output stage and an integrated power drive stage. The power of the former is below a few watts, and the power of the latter is more than ten watts.
②Common models: cd4100, cd4101, cd4102, sl349, etc. cd4100, cd4101, cd4102 have large power-to-volume ratio, single power supply, and are easy to use. They are mainly used in low-power amplifier circuits such as radios and tape recorders. Their power supply voltages are 6v, 7.5v, and 9v respectively. The power supply voltage of the sl349 power driver is divided into 18v and 24v, which are mainly used in audio circuits.
4. Integrated (ttl) NAND gate: 74ls08(4), NOT gate 74ls04, OR gate 74ls32 and cmos circuit cd4011, etc.
Widely used in medium and small scale integrated circuits. Various logic circuits are formed to represent the yes or no relationship between input and output.
5. time base integrated circuit
The 555 integrated timer is a medium-scale integrated circuit that combines analog circuits and digital circuits, and it has 8 pins. It is a circuit that is widely used at present. For example, a monostable trigger composed of a 555 timer can realize timing control and pulse integrity; when used in a multivibrator, it can realize astable control without an external trigger pulse. A rectangular wave of a certain frequency can be output.
6. jk flip-flop: 74ls114, d flip-flop: 74ls74
These two flip-flops can perform two states of "0" and "1" transitions, and are often used in logic components of registers and counters.
7. Counter: 74ls290
It is one of the basic components of computers and digital logic systems. It can accumulate the number of pulses and finally give the accumulated total. It is widely used in twenty-one decimal counters for addition and subtraction counting operations, etc.
8. Decoder: 74 ls42, 74 ls247
The decoder is used for binary decoder, binary decoder and display decoder etc. Its function is to translate the state of the input code (such as 8421 code) into the corresponding output signal to express its original meaning and display it on the display.
9. Encoder: 74 ls147
Used in binary encoder and binary encoder circuits. The 8421 encoding method is commonly used to obtain the one-digit decimal number represented by the binary code.
10. Adder: 74 ls183
For binary summation circuits, such as half adders, full adders, etc.
11. Digital-to-analog conversion d/a: dac0808
The four-bit binary number at the input end is converted into an inverting amplifier formed by an op amp, and the output is an analog quantity.
12. Analog-to-digital conversion a/d: adc0809
Convert the continuous quantity of input analog signal to output discrete digital quantity. The conversion process is completed through four steps of sampling, holding, quantizing, and encoding.
13. Tri-state gate: 74 ls125
In addition to high level and low level, its output terminal also has a third state - high impedance state. It can be used to transmit several different data or control signals in turn with one wire, and is widely used in computers.
14. Data selector: 74 ls153
It can select one of several channels of data to output as needed.