SN74LS191N

Product Overview

• Category: Integrated Circuit (IC)
• Use: Counter/Divider
• Characteristics:
  • High-speed operation
  • Low power consumption
  • Wide operating voltage range
  • TTL compatible inputs
• Package: DIP (Dual In-line Package)
• Essence: A synchronous, reversible, up/down counter with a parallel load capability
• Packaging/Quantity: Available in tubes or reels, quantity varies depending on supplier

Specifications

• Supply Voltage: 4.75V to 5.25V
• Operating Temperature Range: -40°C to +85°C
• Maximum Clock Frequency: 30 MHz
• Maximum Counting Range: 0 to 15 (4-bit binary)
• Output Current: ±8 mA
• Propagation Delay: 18 ns (typical)

Detailed Pin Configuration

The SN74LS191N has a total of 16 pins, which are assigned specific functions:

1. CP (Clock Pulse): Input pin for clock signal.
2. MR (Master Reset): Active low input pin used to reset the counter.
3. P0-P3 (Parallel Data Inputs): Pins for loading initial count value.
4. UP/DOWN: Input pin to select counting direction (up or down).
5. CE (Count Enable): Active low input pin to enable counting.
6. TC (Terminal Count): Output pin indicating when the counter reaches its maximum or minimum value.
7. QA-QD (Outputs): Four output pins representing the current count value.

Functional Features

• Synchronous Operation: The counter advances or decreases its count value synchronously with the clock signal.
• Reversible Counting: The direction of counting can be controlled using the UP/DOWN pin.
• Parallel Load Capability: Allows the initial count value to be loaded through the parallel data inputs.
• Terminal Count Output: The TC pin goes high when the counter reaches its maximum or minimum value, providing a useful signal for further processing.

Advantages and Disadvantages

Advantages: - High-speed operation allows for efficient counting in various applications. - Low power consumption makes it suitable for battery-powered devices. - Wide operating voltage range ensures compatibility with different systems. - TTL compatible inputs simplify integration with other ICs.

Disadvantages: - Limited counting range (0 to 15) due to its 4-bit design. - Propagation delay of 18 ns may introduce timing issues in certain high-frequency applications.

Working Principles

The SN74LS191N operates based on synchronous binary counting principles. It uses flip-flops to store and update the count value. The clock pulse triggers the flip-flops, causing them to change their state and propagate the count value. The direction of counting is determined by the UP/DOWN input. The parallel load capability allows for loading an initial count value, while the terminal count output provides a signal indicating when the counter reaches its maximum or minimum value.

Detailed Application Field Plans

The SN74LS191N can be used in various applications, including:

1. Digital Counters: Used in digital systems to keep track of events, frequencies, or time intervals.
2. Frequency Dividers: Employed to divide the frequency of an input signal by a specific factor.
3. Industrial Control Systems: Integrated into control circuits for monitoring and controlling processes.
4. Communication Systems: Utilized in data transmission and reception circuits for synchronization purposes.
5. Automotive Electronics: Incorporated in vehicle systems for tasks such as speed measurement or event counting.

Detailed and Complete Alternative Models

1. CD40193: Similar 4-bit synchronous up/down counter with parallel load capability.
2. MC14516B: 4-bit binary counter with asynchronous reset and carry output.
3. 74HC191: High-speed CMOS 4-bit synchronous up/down counter.

These alternative models offer similar functionalities and can be used as substitutes for the SN74LS191N in various applications.

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