74HC74 Pinout
74HC74 Dual D Flip-Flop · Dual D flip-flop with asynchronous set/reset; a basic building block of sequential logic.
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | 1CLR · /1CLR | Control | Flip-flop 1 reset (active-low) |
| 2 | 1D | Input | Flip-flop 1 data input |
| 3 | 1CLK | Control | Flip-flop 1 clock (rising edge) |
| 4 | 1PRE · /1PRE | Control | Flip-flop 1 set (active-low) |
| 5 | 1Q | Output | Flip-flop 1 output Q |
| 6 | 1Q̄ · /1Q | Output | Flip-flop 1 inverted output |
| 7 | GND | GND | Ground |
| 8 | 2Q̄ · /2Q | Output | Flip-flop 2 inverted output |
| 9 | 2Q | Output | Flip-flop 2 output Q |
| 10 | 2PRE · /2PRE | Control | Flip-flop 2 set (active-low) |
| 11 | 2CLK | Control | Flip-flop 2 clock (rising edge) |
| 12 | 2D | Input | Flip-flop 2 data input |
| 13 | 2CLR · /2CLR | Control | Flip-flop 2 reset (active-low) |
| 14 | VCC | Power | Supply + (2–6V) |
How to read the 74HC74 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
What does a D flip-flop do?
On the clock rising edge it moves the value of D to Q (Q⁺=D), effectively storing 1 bit and delaying it by one clock; it is the basic unit for registers / frequency division / synchronization.
How do I connect PRE/CLR if unused?
Both are active-low asynchronous set/reset; tie them high (VCC) when unused, otherwise they will force a set/clear.
Want to understand it interactively?
Use this site's "flip-flop simulator" to apply a clock and watch how Q changes.
Pinout data comes from NXP/TI 74HC74 datasheet (standard DIP-14 numbering). Refer to the actual device datasheet as authoritative for the pinout.