MC74HC165AD

Shift Registers Overview

The MC74HC165AD is an 8-bit parallel-in, serial-out shift register manufactured by onsemi using high-performance silicon-gate CMOS technology. It features asynchronous parallel loading and serial shifting capabilities controlled by a Serial Shift/Parallel Load input. The device includes two clock inputs (Clock and Clock Inhibit) that function identically, allowing for flexible timing control or clock inhibition to prevent double clocking. Complementary outputs are available at QH and QH. The HC variant operates within a supply voltage range of 2.0 V to 6.0 V, while the HCT variant is restricted to 4.5 V to 5.5 V. It is housed in a SOIC-16 package.

Shift Registers Feature Summary

• Supports both asynchronous parallel data loading and serial shifting operations via dedicated control inputs.
• Features dual clock inputs that can be combined for independent sources or used as a clock inhibit function.
• Provides complementary non-inverted and inverted outputs from the final stage of the shift register.
• Compatible with standard CMOS outputs and LSTTL outputs when pullup resistors are utilized.

Shift Registers Applications

• Expanding digital input ports for microcontroller systems requiring multiple parallel inputs.
• Interfacing TTL or NMOS outputs to High-Speed CMOS inputs using the HCT variant.
• Keyboard matrix scanning applications utilizing parallel load and serial readout.

Shift Registers Procurement Notes

Verify the specific suffix against the ordering information table to confirm the exact package type and shipping configuration. The base part number MC74HC165A/D corresponds to the SOIC-16 package. Ensure the required voltage range matches the HC or HCT series specifications before procurement. Confirm RoHS compliance status if environmental regulations apply to the assembly process.

Shift Registers Selection Notes

Select the MC74HC165AD for applications requiring wide supply voltage operation between 2.0 V and 6.0 V. Choose the MC74HCT165AD variant if direct interfacing with 5 V TTL logic levels is necessary without additional level shifting components. Consider the pinout compatibility with LS165 devices if replacing legacy designs. Evaluate the noise immunity characteristics inherent to CMOS technology for noisy environments.

Shift Registers Part Context

This component belongs to the 74HC165A family of 8-bit shift registers. It shares pinout compatibility with the older LS165 device but utilizes modern CMOS technology for lower power consumption and higher noise immunity. The family includes variants such as MC74HCT165A for TTL-compatible voltage levels and automotive-grade versions with the -Q suffix for AEC-Q100 qualification.

Shift Registers Replacement Considerations

MC74HC165ADR2G

Shift Registers FAQ

How do the Clock and Clock Inhibit pins function?

Both pins function identically as active-high clocks. They can be used together to inhibit the clock signal; however, the inhibit input should go high only while the clock input is high to avoid double clocking.

What is the difference between the HC and HCT versions?

The MC74HC165A operates with a supply voltage range of 2.0 V to 6.0 V and is compatible with standard CMOS outputs. The MC74HCT165A operates strictly between 4.5 V and 5.5 V and serves as a level converter for interfacing TTL or NMOS outputs.