SN7474 Dual D-Type Flip-Flop IC – DIP-14

The SN7474 is a digital logic integrated circuit containing two independent D-type flip-flops with asynchronous preset and clear inputs. Part of the 7400-series TTL logic family, it is designed for digital data storage, signal synchronization, frequency division, and sequential logic applications.

Each flip-flop stores one bit of binary information and transfers the logic level present at its D input to the Q output on the rising edge of the clock signal.

The SN7474 is suitable for digital electronics experiments, educational projects, breadboard prototyping, and digital control systems.

Key Features

• Dual D-Type Flip-Flops: Two independent flip-flops in one IC.
• Positive-Edge Triggered: Captures input data on the rising edge of the clock.
• Asynchronous Preset and Clear: Independent active-LOW inputs for setting or resetting each flip-flop.
• Complementary Outputs: Provides Q and Q̅ outputs.
• TTL Logic: Designed for standard 5V TTL digital circuits.
• Data Storage: Each flip-flop stores one bit of binary information.
• Frequency Division: Can divide a clock frequency by two when configured appropriately.
• DIP-14 Package: Suitable for breadboards and through-hole PCB assembly.

Technical Specifications

Pin Configuration

D-Type Flip-Flop Truth Table

Notes:

• X = Don't Care.
• PRE = Preset input.
• CLR = Clear input.
• Both preset and clear operate independently of the clock.
• Activating preset and clear simultaneously produces an invalid operating condition and should be avoided.

Connection Example

To operate the first flip-flop:

1. Connect Pin 14 (VCC) to +5V DC.
2. Connect Pin 7 (GND) to ground.
3. Connect Pin 4 (PRE) and Pin 1 (CLR) to logic HIGH.
4. Connect the data signal to Pin 2 (D).
5. Apply a clock signal to Pin 3 (CLK).
6. Read the output from Pin 5 (Q).
7. Use Pin 6 (Q̅) for the inverted output.

On each rising clock edge, the logic level at the D input is transferred to the Q output.

Frequency Divider Connection

To configure the flip-flop as a divide-by-two circuit:

• Connect Q̅ (Pin 6) to D (Pin 2).
• Apply the clock signal to Pin 3.
• Keep PRE and CLR HIGH during normal operation.
• Read the divided clock output from Pin 5.

The output frequency will be half the input clock frequency.

Applications

• Digital Data Storage
• Binary Counters
• Frequency Divider Circuits
• Sequential Logic Systems
• Digital Signal Synchronization
• Clock Control Circuits
• Digital Electronics Education
• Breadboard and PCB Prototyping

Important Notes

• Power Supply: Use a regulated 5V DC supply.
• Clock Trigger: Data is captured on the rising edge of the clock.
• Preset and Clear: Both asynchronous control inputs are active LOW.
• Unused Inputs: Connect unused logic inputs to defined logic levels.
• Decoupling: A 100nF capacitor between VCC and GND is recommended.
• Microcontroller Compatibility: Verify voltage compatibility before connecting to ESP32, Raspberry Pi, or other 3.3V devices.
• Variant Differences: SN7474, SN74LS74, and SN74HC74 have different electrical specifications and should not be treated as identical replacements.

Package Includes

• 1 × SN7474 Dual D-Type Flip-Flop IC (DIP-14)