74HC595 and 74HC164 are widely used 8-bit serial-in, parallel-out shift registers. Both devices allow a microcontroller to control multiple outputs while using only a small number of control lines.
The two ICs have similar basic functions, but their internal architecture is different. The most important difference is that 74HC595 includes an output storage latch and output-enable control, while 74HC164 does not. This difference affects LED displays, cascading, output stability, and circuit design.
For engineers comparing 74HC595 vs 74HC164, the choice depends mainly on whether the application needs independently latched outputs or only basic serial-to-parallel conversion.
74HC595 is an 8-bit serial-in, parallel-out shift register with an additional 8-bit storage latch.
Serial data is shifted into the internal shift register through the data input. A separate latch clock then transfers the shifted data to the output latch.
The parallel outputs can also be placed into a high-impedance state using the output-enable input.
This architecture makes 74HC595 particularly useful for:
LED displays
Seven-segment displays
LED matrices
Digital output expansion
Relay control
Indicator panels
Embedded control systems
Microcontroller projects
The device can also be cascaded to create larger serial-to-parallel output systems.
74HC164 is an 8-bit serial-in, parallel-out shift register designed for straightforward serial-to-parallel data conversion.
Unlike 74HC595, it does not have a separate output storage latch. Its parallel outputs change as data is shifted through the register. TI specifies the HC164 as an 8-bit serial-in, parallel-out shift register with asynchronous reset.
Typical applications include:
LED control
Output expansion
Display systems
Industrial control
Digital logic
Programmable controllers
Embedded electronics
The simpler architecture can be useful when synchronized output updates are not required.
The most important difference is the output latch.
74HC595 has both a shift register and a storage latch. Data can be shifted into the device while the previous output state remains unchanged. After all bits have been loaded, the latch can update the outputs together.
74HC164 does not have this additional storage latch. Its outputs reflect the current shift-register contents as the clock moves data through the device.
This makes 74HC595 more suitable when the outputs need to remain stable during serial data transmission.
The output latch is one of the biggest practical advantages of 74HC595.
For example, suppose eight LEDs are connected to the outputs.
With 74HC595, the MCU can shift eight bits into the device while the LEDs continue displaying the previous pattern. After the data is completely shifted, the latch clock updates all eight outputs.
With 74HC164, the outputs change during the shifting process.
For display applications, this can produce unwanted intermediate states or visible flickering.
Therefore, 74HC595 is often preferred for LED displays and other applications where simultaneous output updates are important.
74HC595 includes an active-low output-enable input.
When output enable is active, the parallel outputs operate normally. When it is disabled, the outputs are placed into a high-impedance state.
This provides additional control over the output pins.
74HC164 does not provide an equivalent output-enable function.
This makes 74HC595 more flexible when the outputs need to be temporarily disconnected from a shared bus or disabled during system operations.
Both devices provide reset functionality, but the implementation is different.
74HC595 has an asynchronous reset for its shift-register section. The reset clears the shift register, while the output latch has its own state.
74HC164 has an asynchronous reset that clears the shift register and forces its outputs low.
This difference should be considered when the power-up and reset behavior of the outputs is important.
HC-series devices generally support a broad supply-voltage range.
For example, TI specifies the CD74HC164 for operation from 2V to 6V.
A 74HC595 implementation can also support a similar HC logic supply range depending on the manufacturer and exact ordering code. An ON Semiconductor 74HC595 datasheet specifies a 2V to 6V operating range.
This allows these devices to be used in many 3.3V and 5V digital systems.
The exact electrical characteristics should always be checked against the selected manufacturer's datasheet.
The two devices do not have identical pin configurations.
A typical 74HC595 includes:
Serial data input
Shift clock
Latch clock
Output enable
Reset
Serial output
Eight parallel outputs
VCC
GND
The ON Semiconductor 74HC595 uses a 16-pin package and assigns separate pins for shift clock, latch clock, output enable, reset, serial input, serial output, and eight parallel outputs.
74HC164 has a simpler interface and is commonly available in 14-pin packages. TI lists PDIP and SOIC 14-pin versions for the CD74HC164.
Because the package and pin assignments differ, 74HC164 is generally not a direct pin-for-pin replacement for 74HC595.
The additional control functions of 74HC595 require more pins.
A typical 74HC595 uses 16 pins.
A typical 74HC164 uses 14 pins.
The 74HC595 needs additional connections for:
These functions make the device more flexible but also increase the pin count.
74HC595 generally provides one serial data input.
74HC164 provides two serial data inputs.
The two 74HC164 serial inputs can be used together as part of the device's data-input control arrangement. TI describes the inputs as two serial data inputs, with either input capable of serving as a data-enable control for the other.
For a simple serial interface, either architecture can work well.
Multiple shift registers can be connected together to control more outputs.
74HC595 provides a dedicated serial output from the final stage, making daisy-chaining straightforward. The shifted data can pass from one 74HC595 to the next.
74HC164 can also be cascaded, but the implementation uses its shift-register output rather than a dedicated separate serial-cascade pin.
For large output arrays, 74HC595 is often convenient because the cascade architecture is designed into the device.
Both devices can be used to drive LEDs.
However, 74HC595 is generally more convenient for displays because its output latch prevents the outputs from changing while new data is being shifted.
This is especially useful for:
Multiple-digit displays
Status indicators
Scrolling displays
Display panels
With 74HC164, each clock pulse directly affects the output state, which can create unwanted transitional patterns when multiple LEDs are being updated.
Both devices are commonly used with Arduino and other microcontroller platforms.
A typical 74HC595 connection requires:
Data
Clock
Latch
Ground
Power
The MCU sends serial data to the 74HC595 and then activates the latch signal to update the outputs.
With 74HC164, the basic interface can be simpler because there is no latch-control signal.
However, the output changes while data is being shifted.
For Arduino projects involving LED displays, 74HC595 is often the more flexible choice.
LED matrices often require frequent updates to multiple outputs.
The output latch of 74HC595 can be useful because data can be prepared in the shift register before being transferred to the outputs.
This helps keep the display transition synchronized.
74HC164 can still be used for simpler LED applications, but designers need to account for the fact that its outputs change during shifting.
For multiplexed displays, timing requirements should be evaluated carefully.
Seven-segment displays are another common application.
A microcontroller may need more output lines than it has available GPIO pins.
A shift register can provide additional outputs using only a few MCU pins.
74HC595 is particularly useful because the display data can be shifted into the register without immediately changing the visible output.
The latch then updates the display.
This can reduce unwanted visual transitions during data transmission.
Both ICs can expand the number of digital outputs available from a microcontroller.
For example, an MCU with only a few available GPIO pins can use serial communication to control eight additional outputs.
74HC595 provides greater output-control flexibility because of its latch and output-enable functions.
74HC164 is a simpler solution when the outputs can change during shifting and no high-impedance output mode is needed.
Clock speed depends on the exact manufacturer, supply voltage, temperature, load, and device version.
For example, TI specifies a typical maximum clock frequency of 24 MHz for its CD74HC164 under the stated conditions, while other 74HC164 specifications can differ by manufacturer and operating conditions.
Likewise, 74HC595 maximum clock frequency varies between manufacturers and specific device families.
Therefore, engineers should compare the exact ordering codes rather than assuming that every 74HC595 or 74HC164 has the same maximum frequency.
74HC595 commonly provides three-state parallel outputs.
This allows the outputs to be disabled and placed into a high-impedance condition through the output-enable input.
74HC164 uses push-pull outputs and does not provide the same output-enable control. TI lists push-pull outputs for the CD74HC164.
This distinction becomes important when multiple devices share a bus.
Both are CMOS logic devices and are generally suitable for low-power digital circuits.
Actual power consumption depends on:
Supply voltage
Clock frequency
Output switching activity
Load capacitance
Number of active outputs
Operating temperature
A higher clock frequency and larger capacitive load increase dynamic power consumption.
For battery-powered equipment, the complete system should be evaluated rather than comparing only the IC's static supply current.
74HC595 is commonly used for:
Serial-to-parallel conversion
Embedded systems
Arduino projects
74HC164 is commonly used for:
Simple output expansion
Industrial logic
Digital control
Both devices have broad application overlap, but 74HC595 offers additional output-control functions.
74HC164 can potentially replace 74HC595 at the functional level in simple serial-to-parallel applications.
However, it is not a drop-in replacement.
A design that depends on the 74HC595 latch or output-enable function cannot simply remove those functions.
The following should be checked:
Number of pins
Pinout
Latch requirement
Output-enable requirement
Reset behavior
Cascade configuration
Output type
Package
Clock speed
If the application only requires basic serial-to-parallel conversion, 74HC164 may be a possible alternative.
74HC595 can provide the basic serial-to-parallel function of 74HC164 while adding a storage latch and output-enable function.
However, the PCB cannot normally use it as a direct pin-for-pin replacement because the package and pin configuration differ.
Firmware may also need additional control for the latch clock.
If the MCU has an available GPIO for the latch signal, migrating to 74HC595 can provide additional output control.
PCB design requirements are relatively straightforward for both devices.
Important considerations include:
Short clock traces
Clean power supply
Local decoupling
Good ground connection
Appropriate output trace width
Signal integrity at higher clock frequencies
For 74HC595, the latch and output-enable signals should also be routed carefully.
When several shift registers are cascaded, clock and serial-data routing becomes increasingly important.
Both devices can operate at relatively high clock rates, but the exact performance depends on the selected part.
At higher speeds, engineers should consider:
Propagation delay
Clock rise and fall time
Trace length
Signal integrity
Setup time
Hold time
Power supply quality
For a design approaching the device's maximum clock frequency, the exact manufacturer's timing specifications should be used.
Both are inexpensive and widely available logic ICs.
74HC164 can have a simple advantage when only basic shift-register functionality is needed.
74HC595 provides more functionality in one IC, which can reduce the need for additional logic components.
The total system cost should include:
IC
PCB area
Additional control logic
MCU GPIO usage
External components
Assembly
For an application requiring output latching, the additional functionality of 74HC595 can simplify the overall design.
Both device families have been widely adopted by semiconductor manufacturers.
However, availability can vary by:
Manufacturer
Temperature grade
Logic family
Production status
Distributor inventory
For production designs, engineers should verify the exact manufacturer part number rather than searching only for the generic 74HC595 or 74HC164 designation.
Choose 74HC595 when the design needs stable outputs during serial shifting, output-enable control, convenient cascading, or synchronized updates.
Choose 74HC164 when a simple 8-bit serial-to-parallel shift register is sufficient and the outputs can change during the shifting process.
For LED displays and multiplexed output systems, the latch in 74HC595 is often a major advantage.
For simple output expansion and basic digital logic, 74HC164 can provide a straightforward solution.
The main differences are:
74HC595
8-bit serial-in, parallel-out shift register
Includes an 8-bit storage latch
Has output-enable control
Provides three-state parallel outputs
Provides dedicated serial output for cascading
Typically uses a 16-pin package
Suitable for LED displays and synchronized output control
74HC164
No separate output storage latch
No output-enable function
Uses push-pull outputs
Provides two serial data inputs
Commonly available in 14-pin packages
Suitable for simpler serial-to-parallel applications
The 74HC595 architecture therefore provides more output-control functionality, while the 74HC164 offers a simpler implementation.
When searching for a 74HC595 replacement, 74HC164 replacement, 74HC595 alternative, or 74HC164 alternative, engineers should first determine whether the application requires the additional functions of 74HC595.
Important parameters include:
Output current
Latch function
A component with the same basic shift-register function is not necessarily a drop-in replacement.
74HC595 and 74HC164 are both useful for expanding digital outputs and converting serial data into parallel signals.
The major selection point is the output architecture.
74HC595 is the better choice when output data must remain stable while new serial data is being shifted.
74HC164 is suitable when the outputs can change during shifting and a simpler circuit is preferred.
For engineers comparing 74HC595 vs 74HC164, the latch, output-enable function, reset behavior, pinout, package, and cascading method should be checked before selecting one device for a new design or using it as a replacement.
ULN2003A vs ULN2803A: Darlington Transistor Array Comparison
MAX3232 vs SP3232: RS-232 Transceiver Comparison
Explore related electronics articles and guides.
Compare LM358 and LM324 operational amplifiers by channel count, package, pinout, performance, and circuit applications to select the right part.
Compare LM7805 and LM317 linear voltage regulators by output voltage, pinout, external components, heat dissipation, and applications.
Compare 1N4007 and 1N5408 rectifier diodes by current rating, voltage rating, package size, and applications to choose the right part for your design.
Learn why engineers upgrade from XC7A100T-2FGG484C to XC7A200T-2FBG484I and what to consider for FPGA resource expansion and system migration.
Compare XC7A100T-2CSG324I and XC7A100T-2FGG484C package options and understand their impact on Artix-7 FPGA design, I/O planning and industrial applications.
Compare XC7Z020-1CLG484I and XC7Z020-2CLG484I speed grades and understand how performance differences affect Zynq-7000 embedded system design.
Understand the differences between XC7Z020-1CLG400I and XC7Z020-1CLG484I and how package selection affects Zynq-7000 embedded system design.
Compare XC7Z020-1CLG400I and XC7Z020-1CLG484I package differences, I/O requirements and design considerations for Zynq-7000 embedded systems.
Compare XC7A35T-1CSG324C and XC7A50T-2CPG236I Artix-7 FPGA devices for industrial control, embedded applications and programmable logic designs.
Explore the differences between XC6SLX45-2CSG324I and XC7A100T-1FGG484C and understand why many FPGA designs migrate from Spartan-6 to Artix-7 platforms.
Compare XC7Z020-1CLG484I and XC7Z020-2CLG484I Zynq-7000 SoC devices including speed grade differences, embedded applications and FPGA design considerations.
Compare XC7A100T-2FGG484C and XC7A200T-2FBG484I Artix-7 FPGA devices for industrial control, image processing, communication and hardware acceleration applicati...
Copyright © ElecSuppliers.com. All Rights Reserved.