An Overview of 74HC373 Octal Transparent D Type Latch
22 November 2023
Ⅲ. Pin configuration and functions of 74HC373
Ⅳ. What are the features of 74HC373?
Ⅴ. Technical parameters of 74HC373
Ⅵ. What are the applications of 74HC373?
Ⅷ. What is the difference between 74HC373 and 74HC573?
The 74HC373 functions as an octal transparent D-type latch and finds extensive use across diverse fields, particularly in scenarios demanding swift and high-performance data transmission. This article aims to provide an overview of the basic concepts, manufacturer, pin configuration and functions, features, technical parameters, working principle and applications associated with the 74HC373.
74HC373 is a high speed CMOS device. The 74HC373 is pin compatible with the Low Power Schottky TTL (LSTTL) family. It has an independent D-type input port and a bus-oriented three-state output port. All latches share a latch enable (LE) terminal and an output enable (OE) terminal.
When OE is low, the contents of the 8 latches can be output normally. When OE is high, the output enters a high-impedance state, and operations on the OE terminal will not affect the state of the latch.
When LE is high, data is input from input Dn to the latch. Under this condition, the latch enters transparent mode. That is to say, the output of the latch changes the same as the corresponding input D. When LE is low, the input data is locked in the latch, and changes in data input D no longer affect the output.
Replacements and equivalents:
• 74HCT373
• 74LS373
74HC373 is manufactured by Fairchild Semiconductor. Fairchild Semiconductor is a semiconductor design and manufacturing company located in Silicon Valley, USA, currently headquartered in Sunnyvale. The company developed the world's first commercial integrated circuit, an achievement slightly ahead of Texas Instruments. Fairchild Semiconductor occupies an important position in the development history of the Silicon Valley semiconductor industry.
On September 19, 2016, ON Semiconductor acquired Fairchild Semiconductor for $2.4 billion. After the acquisition was completed, the long-established Fairchild brand became history. The new company after the merger will uniformly use the "ON Semiconductor" brand. ON Semiconductor has advantages in the field of low and medium voltage and analog control devices, while Fairchild Semiconductor has unique characteristics in the field of medium and high voltage devices. The two companies have many product lines that can complement each other. After their merger, they will provide products and solutions across the full voltage range for the automotive, industrial and communications fields.
The 74HC373 chip has a total of 20 pins, including 8 data input pins (D0~D7), 8 data output pins (Q0~Q7), 1 output enable pin (OE) and 3 control pins (LE, OE and CP). The main functions of these pins are as follows:
1. D0~D7: This is the data input pin, used to input the data to be latched.
2. Q0~Q7: This is the data output pin, used to output latched data.
3. OE: This is the output enable pin, used to control whether the data output is valid.
4. LE: This is the latch enable pin, used for low level latches. When LE is high, the incoming data can be modified by the clock signal on the CP pin.
5. CP: This is the clock pin and is used to control the latch. When a falling edge occurs on CP, the input data will be latched and output to Q0~Q7 after processing.
• Tri-state non-inverting output for bus-oriented applications
• Can operate over a wide supply voltage range, typically 2V to 6V
• It has relatively low power consumption.
• It has storage function to save the input status.
• 74HC373 contains 8 latches, each latch can store one bit of data.
• All latches share a latch enable (LE) terminal and an output enable (OE) terminal.
• 74HC373 has a clock input pin that triggers data transfer by the rising or falling edge of the clock signal.
• Data can be input into the latch through 8 parallel input pins (D0 to D7).
• It has certain anti-interference ability against electrostatic discharge (ESD), which improves the stability of the device.
• Latches are transparent. Under the action of the clock signal, the input data is passed directly to the output, and the state of the latch is changed accordingly.
• Digital switch: It can be used to control digital switches and control the state of other digital circuits through the output of the latch.
• Automotive electronics: In automobile engine control, it can store the engine's operating status in the register, and then transmit the engine's operating status to other devices through the ECU.
• Industrial control: Within robot control systems, the 74HC373 has the capability to store the current motion status of the robot in its register and subsequently relay this information to other devices via the controller.
• Timing control: It can be used to control the timing of digital systems. For example, in a CPU, it can store the execution sequence of instructions in a register, and then control the timing of the CPU based on the sequence of these instructions.
• Communication: In the realm of fiber optic communication, received data can be stored in registers and subsequently transmitted to other devices via fiber optic interfaces.
• Data transmission: In a communication system, it can store the received data in a register and then transmit it to other devices through a data bus or other interface.
• Data storage: 74HC373 can also be used to store data. For example, in a computer, it stores data inside the computer in memory so that it can be read or modified when needed.
When Output Control is low, the contents of the 8 latches can be output normally. When Output Control is high, the output enters a high-impedance state, and operations on the Output Control terminal will not affect the state of the latch.
When the enable terminal Latch Enable is high level, the state of the data output terminal Q of the latch is the same as the data input terminal D, showing a transparent state. When the Latch Enable terminal returns from high level to low level, the data at the input terminal will be locked by the latch, and changes in the data input terminal D will no longer affect the output of the Q terminal.
74HC373 and 74HC573 are both integrated circuits belonging to the 74HC series of CMOS (Complementary Metal Oxide Semiconductor) logic. The two differ in the following aspects.
1. Application scenarios
Due to its output enable control terminal (OE), the 74HC573 is widely used in applications that require output control, such as address buses, data buses, and the buffering of other control signals. In contrast, 74HC373 is mainly used in display screen registers, data memory, CPU state maintenance and state retention.
2. Function
The 74HC373 is a transparent latch with memory, while the 74HC573 is a transparent latch with output enable control. The biggest difference between the two is that 74HC573 has an output enable control terminal, which can be used to control whether the output of the latch is passed to the output port. In contrast, the 74HC373 does not have this feature.
Frequently Asked Questions
1. What is a 74HC373?
74HCT373 is an octal D-type transparent latch featuring separate D-type inputs for each latch and 3-state outputs for bus oriented applications. A latch enable (LE) input and an output enable (OE) input are common to all latches.
2. What is a latch in code?
Latches are digital circuits that store a single bit of information and hold its value until it is updated by new input signals. They are used in digital systems as temporary storage elements to store binary information.
3. What is the difference between 373 and 573 latch?
The difference between 373 and 573 is only in the pin order. 74HC and 74LS have different logic thresholds; the exact CMOS equivalent to 74LS is the 74HCT series.
4. What is 74HC373 used for?
The 74HC373 is suitable for latch ing data with levels, and 74HC377 is suitable for latch ing data with clocks. 74HC373 is more suitable for asynchronous applications, and 74HC377 is suitable for synchronous applications.
5. What are the applications of latches?
Latches are widely used in digital systems for various applications, including data storage, control circuits, and flip-flop circuits. They are often used in combination with other digital circuits to implement sequential circuits, such as state machines and memory elements.
