The 74HC595 is a high-speed CMOS device that consists of an 8-bit storage register and an 8-bit shift register with a 3-state (Tri-state) output. It is the most popular solution for “Pin Expansion” in the microcontroller world. By using only three pins on an Arduino or ESP32 (Data, Clock, and Latch), the 74HC595 can control eight separate output pins. Multiple 74HC595 ICs can also be “daisy-chained” together to control 16, 24, or even 100+ outputs using the same three microcontroller pins, making it indispensable for driving LED matrices and complex displays.
74HC595 Pinout (DIP-16)
The 74HC595 uses a 16-pin package. Note that the output pins are not in sequential order, which is important for PCB layout.
| Pin | Terminal | Function |
| 1 – 7 | Q1 – Q7 | Parallel Data Outputs |
| 8 | GND | Ground (0V) |
| 9 | Q7\ | Serial Out (for daisy-chaining to next IC) |
| 10 | MR\ | Master Reset (Active Low – usually tied to VCC) |
| 11 | SHCP | Shift Register Clock Input |
| 12 | STCP | Storage Register Clock Input (Latch) |
| 13 | OE\ | Output Enable (Active Low – usually tied to GND) |
| 14 | DS | Serial Data Input |
| 15 | Q0 | Parallel Data Output 0 |
| 16 | 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): ±35mA (High drive capability)
- Shift Frequency: Up to 25 MHz (at 5V)
- Propagation Delay: ~13ns
- 3-State Outputs: Allows the outputs to be effectively disconnected.
Key Features & Benefits
- Pin Expansion: Turn 3 microcontroller pins into 8, 16, or more.
- Daisy-Chainable: Serial output allows multiple chips to be https://www.google.com/search?q=linked easily.
- Storage Register: Prevents the “flicker” of outputs while data is being shifted in.
- High Output Drive: Strong enough to drive LEDs directly without extra buffers.
Common Applications
- LED Matrix Control: Driving large grids of LEDs for signs or displays.
- 7-Segment Displays: Controlling multiple digits with minimal wiring.
- Port Expansion: Increasing the number of output pins on an Arduino or ESP32.
- Serial-to-Parallel Conversion: Converting a serial data stream into parallel bits.
74HC595 Equivalent & Substitutes
- 74LS595 (Older TTL version)
- 74HCT595 (TTL-compatible CMOS)
- CD4094 (CMOS 8-stage shift-and-store register)
- SN74HC595 (Texas Instruments direct equivalent)
Related Tutorials on ElxHub
- Basics: Learn more in Integrated Circuits – Basics and Working
- Expansion: See our Tutorial on Shift Registers
- Selection Guide: Compare logic options in our Ultimate IC Selection Guide
Conclusion
The 74HC595 is a “magic” chip for anyone who has ever run out of pins on their microcontroller. Its ability to expand outputs serially while keeping the logic fast and reliable makes it one of the most useful ICs in modern digital prototyping. Whether you are building a giant LED cube or a complex control interface, the 74HC595 is the most efficient way to scale your project.
Download the IC’s Datasheet pdf
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