SN74HC595N: 8-Bit Shift Register with 3-State Outputs

ElecSuppliers Part Number GuideAug 20, 2026

The SN74HC595N is an 8-bit serial-in, parallel-out shift register from Texas Instruments. It combines an 8-bit shift register with an 8-bit storage register and provides parallel 3-state outputs in a 16-pin PDIP package.

The device is useful when a digital system needs additional output lines without dedicating a large number of microcontroller pins to individual signals. Data can be transferred serially into the device and then presented through its parallel outputs.

What Is the SN74HC595N?

The SN74HC595N is designed to expand the number of digital outputs available from a microcontroller or other digital controller.

Instead of requiring eight separate controller pins for eight output signals, the controller can send the required data serially through the shift register. Once the data has been transferred, the storage register can update the parallel outputs.

This architecture makes the SN74HC595N useful in systems where PCB space, controller I/O availability or wiring complexity needs to be reduced.

SN74HC595N Shift Register Architecture

The SN74HC595N contains two separate 8-bit registers.

The first is the serial shift register. Data enters through the serial input and moves through the register with each active clock transition.

The second is the storage register. It holds the shifted data and controls the eight parallel outputs.

Separating the shift and storage operations allows new data to be prepared internally while the existing output state remains unchanged. This can be useful when several outputs need to change together rather than one at a time.

SN74HC595N Serial Data Transfer

The SN74HC595N uses a serial input to receive data from a controller.

A typical system connects the serial data line and shift-register clock to the controller. After the required number of bits have been shifted into the device, the storage-register clock transfers the data to the output register.

This means that multiple output states can be updated using only a small number of controller signals.

The device also provides a serial output that allows multiple SN74HC595N devices to be connected in a chain.

SN74HC595N Cascading

Cascading is one of the most useful features of the SN74HC595N.

Multiple shift registers can be connected sequentially so that data shifted out of one device enters the next device. This allows a controller to expand the number of available outputs without requiring a separate group of control lines for every additional register.

For example, several SN74HC595N devices can be arranged as a longer serial data chain. The controller sends the complete output pattern through the chain and then updates the storage registers.

This approach can be useful for LED arrays, indicator panels and other systems with many digital outputs.

SN74HC595N 3-State Outputs

The eight parallel outputs of the SN74HC595N use a 3-state architecture.

When output enable is active, the stored data can be presented through the output pins. When output enable is disabled, the outputs enter a high-impedance state.

This feature provides additional flexibility when the outputs need to be disconnected from the rest of a digital circuit. It can also be useful in systems where multiple devices share connections or where outputs need to be temporarily disabled.

SN74HC595N Operating Voltage

The SN74HC595N operates across a 2V to 6V supply range.

This range gives the device flexibility for different CMOS logic systems. The electrical characteristics of the input and output signals should still be evaluated at the actual supply voltage used in the application.

At 5V, the device provides ±6mA output drive under the specified conditions.

The maximum supply current is specified at 80µA, although the actual system power consumption also depends on switching activity and the external loads connected to the outputs.

SN74HC595N Clock Performance

The SN74HC595N supports clock frequencies up to 24MHz under the specified conditions.

Its typical propagation delay is approximately 13ns. These characteristics make it suitable not only for low-speed indicator control but also for digital systems requiring relatively fast serial data transfer.

The practical operating speed of a complete system depends on the controller, PCB layout, signal integrity, load and timing requirements.

SN74HC595N Direct Clear Function

The shift register includes a direct clear input.

This allows the shifted data to be cleared without requiring the controller to clock a complete sequence of zeroes through the register.

The clear function can be useful during initialization or when the system needs to place the shift register into a known state.

The clear input affects the shift register, while the separate storage register provides independent control over when the parallel outputs change.

SN74HC595N Package and Temperature Range

The SN74HC595N uses a 16-pin PDIP package.

The N suffix identifies the PDIP package configuration for this specific Part Number. The device is specified for a -40°C to 85°C operating temperature range.

This distinction is important when selecting or replacing a shift register. Other SN74HC595 variants may use different packages, ordering configurations or electrical characteristics, so the complete Part Number should be checked rather than assuming all variants are identical.

SN74HC595N Applications

The SN74HC595N can be used in digital systems that require additional parallel outputs.

Common application areas include LED indicators, display control, relay or control-signal expansion, digital output expansion and microcontroller interface circuits.

It can be particularly useful when a microcontroller has limited GPIO resources but needs to control multiple digital signals.

For LED applications, the actual LED current and total output loading must be evaluated carefully. The SN74HC595N is a logic shift register, not a dedicated high-current LED driver.

SN74HC595N Design Considerations

The main advantage of the SN74HC595N is reducing the number of controller pins required for multiple digital outputs.

However, the serial transfer process introduces a timing requirement. The controller needs to shift the appropriate number of bits into the register before updating the storage register.

When several devices are cascaded, the required transfer time increases with the number of registers. The system firmware should therefore account for the complete serial chain when determining the output update rate.

Engineers should also consider output loading, supply voltage, switching frequency and PCB signal integrity when designing a circuit around the SN74HC595N.

SN74HC595N for GPIO Expansion

The SN74HC595N provides a simple hardware method for expanding digital outputs from a microcontroller.

Its serial-in, parallel-out architecture means that a relatively small number of controller signals can control multiple output channels. The separate shift and storage registers also allow a complete group of outputs to be updated together.

For embedded designs where GPIO availability is a limiting factor, this can be a simpler solution than selecting a larger microcontroller solely to obtain additional output pins.

Choosing the SN74HC595N

The SN74HC595N is a suitable choice when a design requires an 8-bit shift register with parallel 3-state outputs, serial cascading and a through-hole 16-pin package.

Before selecting the device, engineers should verify the required supply voltage, clock speed, output current, temperature range and package.

For production designs, the complete SN74HC595N ordering code should be maintained in the BOM rather than shortening the reference to SN74HC595, because the suffix identifies the specific package and ordering configuration.

The combination of serial data transfer, parallel outputs and cascading makes the SN74HC595N a practical solution for digital output expansion in many embedded and control systems.