IC 74573 – Octal D-Type Transparent Latch

Introduction IC 74573 – Octal D-Type Transparent Latch is an octal D-type transparent latch with three-state outputs, widely used in digital electronics for temporary data storage and buffering. It belongs to the 74 series of TTL (Transistor-Transistor Logic) integrated circuits, which are known for their robustness and reliability in various applications, including microcontroller interfaces, data buses, and memory devices.

Key Features

• Type: Octal D-Type Transparent Latch
• Logic Family: 74 series TTL
• Number of Latches: 8 (Octal)
• Operating Voltage: Typically 4.75V to 5.25V
• Three-State Outputs: Allows for multiplexing data onto a bus
• Propagation Delay: Typically around 15ns
• Latch Enable (LE): Controls the transparency of the latches
• Output Enable (OE): Controls the three-state outputs, allowing the IC to be connected to a bus system

Pin Configuration The IC 74573 is housed in a 20-pin Dual In-Line Package (DIP) with the following pin configuration:

1. Q1 – Output for latch 1
2. Q2 – Output for latch 2
3. Q3 – Output for latch 3
4. Q4 – Output for latch 4
5. Q5 – Output for latch 5
6. Q6 – Output for latch 6
7. Q7 – Output for latch 7
8. Q8 – Output for latch 8
9. GND – Ground
10. OE – Output Enable
11. LE – Latch Enable
12. D8 – Data input for latch 8
13. D7 – Data input for latch 7
14. D6 – Data input for latch 6
15. D5 – Data input for latch 5
16. D4 – Data input for latch 4
17. D3 – Data input for latch 3
18. D2 – Data input for latch 2
19. D1 – Data input for latch 1
20. Vcc – Power supply

Functionality

• Data Latching: The IC 74573 latches data on the D inputs when the Latch Enable (LE) pin is active. When LE is high, the data present on the D inputs is latched and available on the corresponding Q outputs. When LE is low, the outputs remain constant, holding the last latched data.
• Three-State Outputs: The Output Enable (OE) pin controls whether the outputs are active or in a high-impedance state. When OE is low, the outputs are active, and the data from the latches is available on the Q pins. When OE is high, the outputs go into a high-impedance state, effectively disconnecting them from the circuit. This feature is particularly useful for bus systems where multiple devices share the same output lines.

Applications

1. Bus-Oriented Systems: The IC 74573 is commonly used in systems with a shared data bus. Its three-state output capability allows multiple devices to share the same bus without interference, making it ideal for buffering and holding data temporarily.
2. Data Storage and Transfer: In digital systems, the IC 74573 is used to store and transfer data between different parts of a circuit. It can hold data temporarily while the system processes other tasks, ensuring smooth and efficient operation.
3. Microcontroller Interfaces: The IC is often used as an interface between microcontrollers and peripheral devices. It allows microcontrollers to latch data outputs and manage multiple devices on a shared bus with ease.
4. Memory Addressing: In memory systems, the IC 74573 can be used to latch memory addresses, ensuring that the correct data is read or written during each cycle.

Conclusion The IC 74573 is a versatile and reliable component in the 74 series of TTL logic chips. Its ability to latch data and control outputs makes it indispensable in a variety of digital applications, particularly in bus-oriented systems and microcontroller interfaces. Whether you are designing a complex computer system or a simple microcontroller project, the IC 74573 offers flexibility and performance that is essential for efficient data handling and transfer.

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