The 74HC74 is a high-speed CMOS device containing two independent D-type flip-flops with individual data (D), clock (CP), set (SD), and reset (RD) inputs. It is a fundamental building block of sequential logic, allowing a circuit to “remember” its previous state. The 74HC74 is edge-triggered, meaning it stores the state of the D-input at the precise moment the clock signal rises. It is widely used for frequency division, building shift registers, and creating simple “toggle” switches for power control in digital systems.
74HC74 Pinout (DIP-14)
The 74HC74 houses two separate flip-flops. Pins for the first flip-flop are on the left side, and the second are on the right.
| Pin | Terminal | Function |
| 1 | 1RD | Reset for Flip-Flop 1 (Active Low) |
| 2 | 1D | Data Input for Flip-Flop 1 |
| 3 | 1CP | Clock Input for Flip-Flop 1 (Rising Edge) |
| 4 | 1SD | Set for Flip-Flop 1 (Active Low) |
| 5 | 1Q | True Output of Flip-Flop 1 |
| 6 | 1Q\ | Complementary Output of Flip-Flop 1 |
| 7 | GND | Ground (0V) |
| 8 | 2Q\ | Complementary Output of Flip-Flop 2 |
| 9 | 2Q | True Output of Flip-Flop 2 |
| 10 | 2SD | Set for Flip-Flop 2 (Active Low) |
| 11 | 2CP | Clock Input for Flip-Flop 2 (Rising Edge) |
| 12 | 2D | Data Input for Flip-Flop 2 |
| 13 | 2RD | Reset for Flip-Flop 2 (Active Low) |
| 14 | VCC | Positive Supply (2V to 6V) |
Technical Specifications
- Supply Voltage Range (VCC): 2.0V to 6.0V
- Input Voltage (VI): 0V to VCC
- Output Current (IOUT): ±25mA
- Clock Frequency (fmax): 30 MHz to 50 MHz (at 5V)
- Propagation Delay: ~15ns
- Operating Temperature: -40°C to +125°C
Key Features & Benefits
- Dual Channel: Two independent flip-flops in a single 14-pin package.
- Asynchronous Inputs: “Set” and “Reset” work independently of the clock for immediate control.
- Edge Triggering: Precise data capture on the rising edge of the clock pulse.
- Low Power CMOS: Ideal for battery-powered memory and logic states.
Common Applications
- Frequency Dividers: Dividing a clock signal by 2.
- Data Storage: Storing a single bit of information (1 or 0).
- Toggle Switches: Turning a momentary button into a “Push-ON, Push-OFF” switch.
- Phase Detectors: Synchronizing signals in communications circuits.
74HC74 Equivalent & Substitutes
- 74LS74 (Older TTL version)
- 74HCT74 (TTL-compatible CMOS)
- CD4013 (Standard CMOS Dual D-Type Flip-Flop—up to 15V)
- SN74HC74 (Texas Instruments version)
Related Tutorials on ElxHub
- Basics: Learn more in Integrated Circuits – Basics and Working
- Logic Design: Explore our Guide to Flip-Flops and Sequential Logic
- Selection Guide: Compare logic options in our Ultimate IC Selection Guide
Conclusion
The 74HC74 is the essential tool for adding “memory” to a digital circuit. Its dual-package design and robust edge-triggering make it a reliable choice for everything from simple LED toggles to complex timing dividers. For any designer moving beyond basic gates into the world of sequential logic, the 74HC74 is a fundamental IC that delivers consistent performance.
Download the IC’s Datasheet pdf
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