SN74LS90N

Product Overview

• Category: Integrated Circuit (IC)
• Use: Counter
• Characteristics: TTL Logic, 4-bit Decade Counter
• Package: DIP-14 (Dual In-Line Package with 14 pins)
• Essence: The SN74LS90N is a synchronous, presettable, 4-bit decade counter that counts in decimal from 0 to 9. It is widely used in digital electronics for counting applications.
• Packaging/Quantity: Available in tubes or reels, with a quantity of 25 units per tube/reel.

Specifications

• Supply Voltage: 4.75V to 5.25V
• Logic Family: LS-TTL (Low Power Schottky Transistor-Transistor Logic)
• Operating Temperature Range: 0°C to 70°C
• Propagation Delay: 15ns (typical)
• Maximum Clock Frequency: 42MHz

Detailed Pin Configuration

The SN74LS90N has a total of 14 pins, each serving a specific purpose:

1. VCC - Positive power supply voltage
2. GND - Ground reference
3. CP - Clock input
4. MR - Master Reset input
5. QA - Output A
6. QB - Output B
7. QC - Output C
8. QD - Output D
9. RC - Ripple Carry output
10. RCO - Ripple Carry output enable
11. LT - Lamp Test input
12. BI/RBO - Borrow-In/Borrow-Out
13. A - Preset input A
14. B - Preset input B

Functional Features

• Synchronous operation allows precise control over the counting sequence.
• Presettable inputs (A and B) enable the user to set the initial count value.
• Ripple Carry output (RC) provides a carry signal for cascading multiple counters.
• Borrow-In/Borrow-Out (BI/RBO) allows the SN74LS90N to be used as a BCD subtractor.

Advantages and Disadvantages

Advantages

• Low power consumption due to LS-TTL technology.
• Compact DIP-14 package allows easy integration into various circuit designs.
• Precise counting sequence with synchronous operation.

Disadvantages

• Limited count range from 0 to 9.
• Not suitable for applications requiring larger counter sizes.

Working Principles

The SN74LS90N operates based on the principle of synchronous counting. The clock input (CP) triggers the counter to increment its count value by one on each rising edge of the clock signal. The preset inputs (A and B) allow the user to set the initial count value. The outputs (QA, QB, QC, QD) represent the current count in binary-coded decimal (BCD) format.

Detailed Application Field Plans

The SN74LS90N finds applications in various fields, including:

1. Digital frequency dividers
2. Industrial automation systems
3. Electronic voting machines
4. Digital clocks and timers
5. Traffic light control systems

Detailed and Complete Alternative Models

There are several alternative models available that offer similar functionality to the SN74LS90N. Some popular alternatives include:

1. CD4017 - CMOS Decade Counter/Divider IC
2. 74HC390 - High-Speed CMOS Logic Dual Decade Counter
3. CD4026 - CMOS Decade Counter/Divider with Decoded 7-Segment Display Outputs

These alternative models can be considered based on specific project requirements and compatibility with other components.

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