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Have you ever wanted to control many LEDs or sensors with a microcontroller but ran out of pins? The SN74HC595N shift register is a handy chip that solves this problem! This tiny device lets you expand the number of outputs your project can handle.
In this blog, we’ll explore its pinout, features, and how to use it. Whether you’re a beginner or a hobbyist, this guide will help you understand the SN74HC595N in simple terms.
A shift register is a digital circuit that stores and moves data. Imagine a row of people passing a ball from one to another—the ball represents data, and each person is a storage unit. The SN74HC595N is an 8-bit shift register, meaning it can store and move 8 pieces of data (like turning 8 LEDs on/off).
Figure 2: PCB Footprint - Texas Instruments SN74HC595N
Figure 3: 3D Model - Texas Instruments SN74HC595N
The SN74HC595N comes in a DIP (Dual In-line Package):
The SN74HC595N is manufactured by Texas Instruments (TI), a leading global semiconductor company founded in 1930. Texas Instruments designs and produces a wide range of electronics, including analog chips, embedded processors, and logic devices like the SN74HC595N.
SN74HC595N Pinout
SN74HC595N
Here’s a comprehensive breakdown of the SN74HC595N 16-pin shift register, including pin functions, types, and practical usage tips:
| Pin # | Pin Name | Type | Direction | Function | Voltage Range | Key Notes |
|---|---|---|---|---|---|---|
| 8 | GND | Power | - | Ground connection | 0V | Must connect to the circuit’s ground. |
| 16 | VCC | Power | - | Power supply input | 2V–6V | Use 5V for most Arduino/RPi projects. |
| 14 | SER | Input | In | Serial Data Input | 0V–VCC | Receives data bit-by-bit (e.g., from a microcontroller). |
| 11 | SRCLK | Input | In | Shift Register Clock | 0V–VCC | Clock signal to shift data into the register (triggered on rising edge). |
| 12 | RCLK | Input | In | Latch Clock (Storage Register Clock) | 0V–VCC | Copies shifted data to output pins on rising edge. |
| 13 | OE ( ) | Input | In | Output Enable (Active Low) | 0V–VCC | Pull to GND to enable outputs. Pull to VCC to disable (turn off). |
| 10 | SRCLR ( ) | Input | In | Master Reset (Active Low) | 0V–VCC | Pull to GND to clear shift register. Tie to VCC if unused. |
| 15 | Q0 | Output | Out | Output Pin 0 | 0V–VCC | First output pin (supports up to 35mA current sink). |
| 1–7 | Q1–Q7 | Output | Out | Output Pins 1–7 | 0V–VCC | Drive LEDs, relays, or sensors. Sequence: Q1=Pin 1, Q7=Pin 7. |
| 9 | Q7' | Output | Out | Serial Output (Cascading) | 0V–VCC | Connects to SER of the next chip in a chain. |
| Category | Specification | Details | Notes |
|---|---|---|---|
| General | Supply Voltage (VCC) | 2.0V to 6.0V | Compatible with 3.3V and 5V systems. Ideal for Arduino/RPi projects. |
| Operating Temperature | -40°C to +85°C | Suitable for extreme environments (e.g., outdoor projects). | |
| Package Type | PDIP-16 (Plastic Dual In-line) | Dimensions: 19.3mm x 6.35mm x 4.57mm. Breadboard-friendly. | |
| Logic Family | HC (High-Speed CMOS) | Balances speed and power efficiency. | |
| Electrical | Output Current (per pin) | 35 mA (max) | Can drive LEDs directly (use resistors!). |
| Total Output Current | 70 mA (max for all pins combined) | Avoid exceeding to prevent overheating. | |
| Input Current (per pin) | ±1 µA (typical) | Very low input leakage. | |
| Output Voltage (HIGH) | VCC - 0.1V (min) | Near full voltage for strong signal integrity. | |
| Output Voltage (LOW) | 0.1V (max) | Minimal voltage drop when sinking current. | |
| Input Voltage Logic Levels | HIGH: ≥70% of VCC LOW: ≤30% of VCC |
For 5V: HIGH ≥3.5V, LOW ≤1.5V. | |
| Power Dissipation | 500 mW (max) | Use heat sinks in high-current applications. | |
| Timing | Clock Frequency | 100 MHz (max) | Fast enough for LED matrices or fast data shifting. |
| Propagation Delay | 13 ns (typical, CLK to output) | Minimal delay for real-time applications. | |
| Rise/Fall Time (Outputs) | 6 ns (typical) | Sharp signal edges for noise immunity. | |
| Setup Time (SER to SRCLK) | 20 ns (min) | Data must be stable before clock edge. | |
| Hold Time (SER to SRCLK) | 5 ns (min) | Data must remain stable after clock edge. | |
| Physical | Input/Output Capacitance | 3.5 pF (typical) | Minimal signal distortion in high-speed circuits. |
| ESD Protection | 2 kV (Human Body Model) | Protects against static discharge during handling. | |
| Thermal Resistance | 80°C/W (Junction-to-Ambient) | Indicates heat dissipation capability. | |
| Functional | Number of Bits | 8-bit shift register + 8-bit storage register | Separate registers for shifting and displaying data. |
| Daisy-Chaining Support | Yes (via Q7' pin) | Connect multiple chips for 16, 24, etc., outputs. | |
| Reset Functionality | Master Reset (SRCLR pin) | Active-low pin clears shift register (does not affect storage register). | |
| Output Enable (OE) | Active-low control | Turn outputs on/off without losing data. Use PWM for dimming. |
The chip can store and shift 8 bits of data, letting you control 8 outputs using just 3 microcontroller pins.
Data shifted into the chip is held in a storage register until you’re ready to display it, preventing flickering in LEDs or displays.
Use the Q7’pin to connect multiple SN74HC595N chips, expanding outputs to 16, 24, or more with the same 3 control pins.
Works at up to 100 MHz, making it fast enough for LED matrices, displays, or rapid sensor updates.
Compatible with 3.3V (Raspberry Pi) and 5V (Arduino) systems, offering flexibility for various projects.
The OE pin (active low) lets you turn outputs on/off instantly. Use PWM here for LED brightness control.
Pull the SRCLR pin low to clear all data in the shift register, resetting outputs in milliseconds.
Uses just 1 µA when idle and minimal power during operation, ideal for battery-powered devices.
Each output pin can sink up to 35 mA, enough to power LEDs or small relays directly (add resistors for LEDs!).
Fits easily on breadboards, with labeled pins for hassle-free prototyping.
Withstands electrostatic discharges up to 2 kV, protecting the chip from accidental static damage.
Works seamlessly with both CMOS (e.g., Raspberry Pi) and TTL (e.g., Arduino) logic levels.
Outputs can be disabled (high-impedance state), useful for sharing buses or reducing power use.
The shift register SN74HC595N is like a digital warehouse that stores and organizes data to control multiple devices. Let’s break down its operation step by step:
Combine the SN74HC595N with a input shift register (e.g., 74HC165) to read multiple buttons or switches.
Sensor Multiplexing: Read data from multiple sensors (e.g., temperature, light) using fewer pins.
Convert serial data (e.g., from a microcontroller) into parallel signals for devices needing parallel input.
Use the SN74HC595N to control SD card modules, indicator LEDs, or status displays in data loggers.
Teaching Tool: Demonstrate binary counting, data shifting, or digital logic in classrooms.
The SN74HC595N is widely used, but several equivalent or similar shift registers can replace it depending on your project’s needs. Here’s a detailed table of alternatives:
| Equivalent IC | Manufacturer | Key Differences | Notes |
|---|---|---|---|
| 74HC595 | Various (TI, NXP, etc.) | Functionally identical to SN74HC595N. | Same specs, but different part numbering. Drop-in replacement. |
| CD74HC595 | Texas Instruments | Similar specs, but in a different package (e.g., SOIC-16). | Ideal for surface-mount (SMD) projects. |
| M74HC595 | STMicroelectronics | Same logic and pinout, but slightly different timing characteristics. | Check datasheet for timing if used in high-speed (>50 MHz) circuits. |
| HEF4094 | NXP | 8-bit shift register with latching, but 3.3V–15V voltage range. | Better for higher voltage systems (e.g., 12V), but slower (~20 MHz). |
| 74HCT595 | NXP/TI | TTL-compatible inputs (works with 4.5V–5.5V). | Use when interfacing with TTL devices (e.g., older microcontrollers). |
| TPIC6B595 | Texas Instruments | High-current (150 mA per output) open-drain outputs. | Drives motors, relays, or high-power LEDs directly. |
| 74LS595 | Various | TTL logic family (5V-only), lower speed (~35 MHz). | Older design; requires 5V logic. |
| STP16DP05 | STMicroelectronics | 16-bit shift register with constant-current LED drivers. | For large LED arrays; simplifies LED resistor calculations. |
| 74HC164 | Various | 8-bit shift register without a storage latch. | Cheaper but lacks simultaneous output updates (may cause flickering). |
| Feature | SN74HC595N | 74HC164 | TPIC6B595 | HEF4094 | 74HC165 |
|---|---|---|---|---|---|
| Type | 8-bit output | 8-bit output | 8-bit output | 8-bit output | 8-bit input |
| Voltage Range | 2V–6V | 2V–6V | 3V–5.5V | 3V–15V | 2V–6V |
| Output Current (per pin) | 35 mA (sink) | 25 mA (sink) | 150 mA (sink) | 25 mA (sink) | N/A (input device) |
| Storage Latch | Yes ✅ | No ❌ | Yes ✅ | Yes ✅ | N/A |
| Daisy-Chaining | Yes ✅ | Yes ✅ | Yes ✅ | Yes ✅ | Yes ✅ |
| Speed (Max Clock) | 100 MHz | 50 MHz | 25 MHz | 20 MHz | 80 MHz |
| Key Advantage | Balance of speed, cost, and features | Cheaper, simpler | High-current open-drain outputs | High-voltage support | Reads multiple inputs |
| Best For | LEDs, displays, GPIO expansion | Basic shifting tasks | Motors, relays, high-power LEDs | Industrial 12V systems | Reading buttons/sensors |
The SN74HC595N is a versatile shift register that lets you control multiple outputs with minimal microcontroller pins. Below is a detailed walkthrough of building a SN74HC595N circuit:
| SN74HC595N Pin | Connected To | Purpose |
|---|---|---|
| VCC (16) | 5V (Arduino 5V) | Powers the chip. |
| GND (8) | GND (Arduino GND) | Ground connection. |
| SER (14) | Arduino Digital Pin 2 | Serial data input (sends bits one by one). |
| SRCLK (11) | Arduino Digital Pin 3 | Shift Register Clock (pulse to read each bit). |
| RCLK (12) | Arduino Digital Pin 4 | Latch Clock (pulse to update outputs). |
| OE (13) | GND | Enable outputs (tie to GND to turn on). |
| SRCLR (10) | 5V | Disable reset (tie to VCC if not used). |
| Q0–Q7 (15,1–7) | LEDs (with 220Ω resistors) | Output pins to control devices. |
| Q7’ (9) | Unused (or next chip’s SER) | Daisy-chaining output (for multiple chips). |
1.Shift Data In:
2.Latch Data:
A pulse to RCLK (Pin 12) copies the data from the shift register to the storage register, updating the Q0–Q7 outputs.
3.Output Control:
LEDs connected to Q0–Q7 light up according to the binary pattern sent.
The SN74HC595N shift register is a powerful tool for expanding your project’s outputs. With its easy daisy-chaining and low cost, it’s perfect for LED displays, sensors, and more. By following this guide, even beginners can master this versatile chip!
The maximum data transfer rate of the SN74HC595N can reach up to 59 MHz when the supply voltage (VDD) is 6V. And its typical shift-out frequency is 100 MHz.
1.Connect its VCC to +5V and GND to ground, then link the serial data input (DS), shift clock (SHCP), and latch clock (STCP) pins to a microcontroller. 2. Send 8 bits of data serially via DS (synchronized with SHCP), then pulse STCP to update the 8 parallel outputs. 3.Tie MR to VCC (no reset needed) and OE to GND to enable outputs.
The SN74HC595N is a simple 8-bit shift register IC. It can be used to expand digital outputs in embedded systems, displays, and control applications.
The 74HC595 is an 8-bit serial-in, parallel-out shift register with a storage register and tri-state output buffers.
The 74HC595 is a powerful and flexible shift register that allows you to expand the number of digital outputs on your microcontroller using only 3 control pins (DS, SHCP, STCP).
The shift register clock (SHCP, pin 11) is one of the key control pins responsible for shifting serial data into the register. It works in conjunction with the DS pin to load the data bit by bit. After all the bits are shifted in, the STCP pin is used to update the parallel outputs.
A register is a storage element that stores a fixed number of bits. It is used to temporarily store data during processing. The data in a register can be read or written in parallel. While a shift register is a digital storage circuit in devices such as calculators, computers, and data processing systems.
A shift register circuit is a digital circuit that: 1. Shifts data left or right through a sequence of flip-flops. 2. Converts between serial and parallel data formats. 2. Used as a temporary storage buffer or delay line. 3. Used in serial communications, LED control, signal processing, etc.
The 74HC595 is an 8-bit serial-in, parallel-out (SIPO) shift register with tri-state outputs:Shift register - This register's role is to receive data input bit by bit (serial). Storage register - This register holds the data and then sends it all at once (in parallel) to the output pins.
The SN74HC595N operates within a wide voltage range of 2V to 6V. This flexibility allows it to be used in various electronic applications with different power supply requirements.
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