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7408 Integrated Circuit: A Classic TTL (transistor-transistor logic) Type IC
The 7408 integrated circuit is a classic TTL (transistor-transistor logic) type IC, which is widely used in various digital circuits. It contains four 2-input AND gates, each with two inputs and one output, for performing logical AND operations. The following is a detailed introduction to the 7408 integrated circuit:
IC 7408 Basic Function and Principle
The 7408 chip is a four-input AND gate integrated circuit (IC), and the output of each AND gate is the result of the logical AND operation of the corresponding two inputs. The output of the logical AND gate is high (1) only when all inputs are high (1), otherwise the output is low (0).
Logic Symbol and Truth Table:
| A | B | Output (Y) |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
Logic Formula:
For each AND gate, the output Y=A⋅B, that is, the logical AND operation of A and B.
7408 IC Pin Assignment and Package
The 7408 chip is usually packaged in a 14-pin DIP (dual in-line package), and there are other packages such as SOP (small outline package) and TSSOP (thin small outline package). The following are the pin functions of the DIP-14 package:
| Pin Number | Pin Name | Description |
|---|---|---|
| 1 | A1 | Input A1 (First input of the first AND gate) |
| 2 | B1 | Input B1 (Second input of the first AND gate) |
| 3 | Y1 | Output Y1 (Output of the first AND gate) |
| 4 | A2 | Input A2 (First input of the second AND gate) |
| 5 | B2 | Input B2 (Second input of the second AND gate) |
| 6 | Y2 | Output Y2 (Output of the second AND gate) |
| 7 | GND | Ground (Connect to 0V) |
| 8 | A3 | Input A3 (First input of the third AND gate) |
| 9 | B3 | Input B3 (Second input of the third AND gate) |
| 10 | Y3 | Output Y3 (Output of the third AND gate) |
| 11 | A4 | Input A4 (First input of the fourth AND gate) |
| 12 | B4 | Input B4 (Second input of the fourth AND gate) |
| 13 | Y4 | Output Y4 (Output of the fourth AND gate) |
| 14 | VCC | Power supply (Typically connect to +5V) |
Chip 7408 Working Principle and Electrical Characteristics
The 7408 chip contains four independent AND gates, each of which has two inputs and one output. When the signal at the input meets the logic requirements of the AND gate, the output returns the result of the logic AND.
Power supply voltage: The standard operating voltage is +5V (common range: 4.75V - 5.25V).
Input voltage: The TTL input voltage standard is 0V (logic low) to 2V (logic high), and above 2V is regarded as logic 1.
Output current: Each output can provide a maximum current of 16mA, which is suitable for driving TTL input.
Power consumption: The 7408 chip consumes a certain amount of power when working, but it is usually low, with a typical value of about 10mW, depending on the usage environment.
Temperature range: The common industrial temperature range is -40°C to +85°C, and the commercial temperature range is 0°C to +70°C.
IC 7408 Datasht PDF
IC 7408 Application Areas
The 7408 chip can be used in various digital circuits, mainly in the following areas:
Logic operation circuit: used as a basic logic operation element to build complex digital circuits.
Combinational logic circuit: used to design combinational logic circuits such as adders, multipliers, encoders, decoders, etc.
Switching circuit: Simple switch control can be achieved through AND gates to control the transmission of signals.
Digital control system: In digital control systems, 7408 can achieve logical decisions, such as switch control, alarm systems, etc.
Sequential circuit: Through the combination of AND gates, the design of sequential logic circuits can be achieved.
IC 7408 Equivalent And Compatible Models
There are several compatible versions of the 7408 chip, usually based on different technologies or logic families:
74LS08: Low Power Schottky series, with lower power consumption characteristics, suitable for high-density integrated circuit design.
74HC08: High-level CMOS series, providing higher input impedance, lower power consumption and a wider operating voltage range (usually 2V to 6V).
74HCT08: High-level CMOS TTL compatible series, suitable for applications that require compatibility with standard TTL logic, with low power consumption characteristics.
Many well-known semiconductor manufacturers produce and provide 7408 chips or their compatible versions. Here are some major manufacturers:
1. Texas Instruments (TI)
Product name: 74LS08, 74HC08, 74HCT08, etc.
Description: As one of the world's leading semiconductor manufacturers, TI offers a variety of versions of the 7408 chip, including standard TTL (LS series), low-power Schottky (LS series), and CMOS versions (HC and HCT series).
2. ON Semiconductor
Product name: 74LS08, 74HC08, 74HCT08, etc.
Description: ON Semiconductor (now acquired Fairchild Semiconductor) also offers a variety of TTL and CMOS versions of AND gates based on the 7408 design.
3. NXP Semiconductors
Product name: 74LS08, 74HC08.
Description: NXP offers multiple versions of the 7408 series, including TTL and CMOS versions, which are commonly used in industrial and consumer electronics.
4. STMicroelectronics
Product name: 74LS08, 74HC08, 74HCT08, etc.
Description: STMicroelectronics offers a wide range of integrated circuits in the 7408 series, which are widely used, especially in industrial applications.
5. Fairchild Semiconductor (now part of ON Semiconductor)
Product Name: 74LS08, 74HC08.
Description: Fairchild, once a major supplier of 7408 chips, is now part of ON Semiconductor. Its LS series and HC series versions can still be found on the market.
6. Microchip Technology
Product Name: 74LS08, 74HC08.
Description: Microchip offers a wide range of logic gate ICs, including several versions of the 7408 series.
7. Broadcom (formerly Avago Technologies)
Product Name: 74LS08, 74HC08.
Description: Broadcom offers compatible 7408 logic gate ICs, mainly used in high-performance and communication equipment.
8. Rohm Semiconductor
Product Name: 74LS08, 74HC08.
Description: Rohm offers a variety of low-power logic ICs, including CMOS and TTL versions of the 7408 series.
9. Toshiba
Product Name: 74LS08, 74HC08.
Description: Toshiba offers TTL and CMOS versions of the 7408, similar to those offered by other manufacturers.
10. Sanken Electric
Product Name: 74LS08.
Description: Sanken offers some older TTL logic ICs, the 7408 being one of them, suitable for more basic digital circuits.
Commonly Used Circuits
The 7408 is often used to implement simple AND gates. For example, the following circuit shows how to implement a basic AND gate with the 7408:
+5V ------> A (Input 1)
|
|
| +------------------+
| | |
+----> B (Input 2) ---> Y (Output)
(7408)
7408 IC Packages and Storage
The 7408 chip is commonly available in a DIP-14 (dual inline package), but there are other package types such as SOP-14 (small outline package) and TSSOP (thin small outline package). These packages are available in different sizes and to suit different mounting requirements.
Where to buy 7408 IC
The 7408 chip can be purchased through Daenic electronic component distributors
Summary
The 7408 integrated circuit is a very classic TTL logic gate chip that is widely used in digital circuits. It contains four 2-input AND gates that can be used to implement a variety of digital logic functions. It is still used in many electronic products because of its simple operating principle, low power consumption and reliability. With various packaging forms, the 7408 is suitable for a variety of designs and experiments.
7408 Integrated Circuit FAQs
1. What is the 7408 chip?
The 7408 is a TTL (transistor-transistor logic) integrated circuit that contains four 2-input AND gates. Each AND gate has two inputs and one output, and performs a logical AND operation. The output is high (1) only when both inputs are high (1), otherwise the output is low (0).
2. What are the applications of the 7408 chip?
The 7408 chip is widely used in various digital circuits. The main applications include:
Basic logic operations: implement logical AND operations.
Combinational logic circuits: such as adders, multipliers, encoders, decoders, etc.
Switching circuits: in situations where switch control is required, such as safety control systems, etc.
Timing circuits: can be used together with other logic gates to build timing circuits.
Digital control systems: used for switch control, fault detection, alarm systems, etc.
3. What is the difference between the 7408 and other AND gate chips?
The 7408 chip belongs to the TTL series, with a standard power supply voltage of +5V and an operating temperature range of typically -40°C to +85°C. The differences from other logic gate chips are as follows:
74LS08: Low-power Schottky (LS) series with lower power consumption.
74HC08: High-level CMOS series with lower power consumption, higher input impedance, and a wider operating voltage range (typically 2V to 6V).
74HCT08: High-level CMOS TTL compatible series, suitable for applications compatible with standard TTL logic.
4. How to choose the right AND gate chip version?
Choosing the right AND gate chip version depends on the following factors:
Power supply voltage: Make sure the operating voltage of the selected chip matches the system power supply. TTL versions usually operate at 5V, and CMOS versions (such as 74HC08 and 74HCT08) support a wider voltage range.
Power consumption: If the application has high power consumption requirements, it would be more appropriate to choose a low-power version (such as 74LS08 or 74HC08).
Input level compatibility: If it is compatible with other TTL or CMOS logic circuits, the 74HCT08 may be a better choice because it has TTL-compatible input levels.
Operating temperature: If the application requires operation under more extreme temperature conditions, chips with an industrial (-40°C to +85°C) temperature range may be more suitable.
5. What is the operating voltage of the 7408 chip?
The 7408 chip usually operates at a +5V power supply voltage, and the typical operating voltage range is 4.75V to 5.25V, which is also the operating voltage commonly used by TTL series logic gates.
6. Is the 7408 chip directly compatible with CMOS circuits?
The 7408 is a logic gate based on TTL technology, while the 74HC08 or 74HCT08 is a CMOS-compatible version. Although the 7408 is only compatible with other TTL circuits, the 74HCT08 has TTL compatible input levels, so it can be used in systems with CMOS output levels and is compatible with TTL logic gates.
7. What are the packages of the 7408 chip?
The 7408 chip has a variety of packages, the most common of which is DIP-14 (dual in-line package). In addition, SOP (small outline package) and TSSOP (thin small package) can also be provided, which are suitable for different installation methods and application requirements.
8. How to test the function of the 7408 chip?
To test the function of the 7408 chip, you can use the following method:
Prepare the test circuit: connect the input of the 7408 to different logic levels (high and low), and connect the output to an oscilloscope or multimeter.
Test the logic state: provide different combinations (00, 01, 10, 11) to the input respectively, and observe the changes at the output.
When both A and B are 1, the output should be 1.
For other input combinations, the output should be 0.
This method can verify the normal operation of the AND gate.
10. What are the alternatives to the 7408 chip?
Some common alternatives to the 7408 chip include:
74LS08: Low-power Schottky series (low-power version).
74HC08: High-level CMOS series (for applications with lower power consumption and higher voltage range).
74HCT08: High-level CMOS TTL compatible series (for applications compatible with TTL systems).
These alternative chips have similar functions and pin layouts, but may differ in power consumption, speed, and input and output levels.
