SN74LS90D

Product Overview

• Category: Integrated Circuit (IC)
• Use: Counter
• Characteristics: TTL Logic, 4-bit Decade Counter
• Package: DIP (Dual In-line Package)
• Essence: A high-speed, low-power counter IC used in various digital applications.
• Packaging/Quantity: Available in tubes or reels, quantity varies based on supplier.

Specifications

• Supply Voltage: 4.75V to 5.25V
• Operating Temperature Range: -40°C to +85°C
• Maximum Clock Frequency: 42 MHz
• Number of Counting Stages: 4
• Output Type: TTL Compatible
• Propagation Delay: 15 ns (typical)

Detailed Pin Configuration

The SN74LS90D has a total of 14 pins, each serving a specific function:

1. VCC: Positive power supply (+5V)
2. GND: Ground (0V)
3. MR: Master Reset (active low)
4. CP0: Clock Input for Stage 0
5. CP1: Clock Input for Stage 1
6. CP2: Clock Input for Stage 2
7. CP3: Clock Input for Stage 3
8. Q0: Output of Stage 0
9. Q1: Output of Stage 1
10. Q2: Output of Stage 2
11. Q3: Output of Stage 3
12. TC: Terminal Count Output (active low)
13. RB: Ripple Blanking Output
14. QA: Auxiliary Output

Functional Features

• Asynchronous Master Reset allows resetting the counter to zero.
• High-speed operation with minimal power consumption.
• Outputs can be cascaded to create larger counters.
• Terminal Count output indicates when the counter reaches its maximum value.
• Ripple Blanking output simplifies cascading multiple counters.

Advantages and Disadvantages

Advantages: - High-speed operation enables efficient counting in various applications. - Low power consumption makes it suitable for battery-powered devices. - Cascadable design allows building larger counters easily.

Disadvantages: - Limited number of counting stages (4 bits). - Requires external components for more complex operations. - Not suitable for high-frequency applications due to propagation delay.

Working Principles

The SN74LS90D is a synchronous counter that counts up from zero to nine. It utilizes flip-flops and logic gates to achieve the counting functionality. The clock inputs (CP0 to CP3) trigger the counter to increment its value on each rising edge. The Master Reset (MR) input resets the counter to zero when activated. The outputs (Q0 to Q3) represent the current count, while the Terminal Count (TC) output indicates when the maximum count is reached.

Detailed Application Field Plans

The SN74LS90D finds applications in various digital systems, including:

1. Frequency Dividers: Used to divide an input frequency by 10 or its multiples.
2. Digital Timers: Provides accurate timing control in electronic circuits.
3. Event Counters: Counts the occurrence of specific events in a system.
4. Sequential Logic Circuits: Forms the basis for designing sequential circuits.
5. Industrial Control Systems: Used in automation and control applications.

Detailed and Complete Alternative Models

1. CD4017: CMOS Decade Counter with 10 outputs.
2. 74HC163: High-Speed Synchronous Counter with 4-bit binary output.
3. CD4029: Presettable Up/Down Counter with parallel load capability.
4. 74F161: Synchronous 4-bit Binary Counter with asynchronous reset.

These alternative models offer similar functionality to the SN74LS90D and can be used as replacements based on specific requirements.

In conclusion, the SN74LS90D is a versatile 4-bit decade counter IC that provides high-speed counting capabilities in various digital applications. Its low power consumption, cascading ability, and synchronous operation make it a popular choice among designers. However, its limited counting stages and propagation delay should be considered when selecting this IC for specific projects.