74HC109D/AUJ

Overview

The 74HC109D/AUJ is a dual J-K flip-flop manufactured by Nexperia (formerly NXP) in the 74HC logic series. It features positive-edge triggering with individual set, reset, and clock inputs for each flip-flop. The device operates within a supply voltage range of 2.0 V to 6.0 V and supports outputs that directly interface with CMOS, NMOS, and TTL systems. Packaged in a 16-lead SOIC (SOT109), it provides standard output capability and includes clamp diodes on inputs for ESD protection and current limiting resistor compatibility.

Feature Summary

• Dual J-K flip-flops with independent set, reset, and clock controls
• Positive-edge triggering reflects input changes at outputs during low-to-high clock transitions
• Direct interface capability with CMOS, NMOS, and TTL logic families
• Input clamp diodes enable use of current limiting resistors for voltage interfacing

Applications

• Digital counting circuits requiring toggle or hold modes
• Data storage elements in sequential logic systems
• Interface modules connecting different logic voltage levels
• Shift register configurations using J-K topology

Procurement Notes

Verify the manufacturer designation carefully, as Nexperia acquired NXP's Standard Products division. Ensure the ordering suffix matches the required package variant and temperature grade. Confirm AEC-Q100 qualification if automotive reliability standards are mandatory for the application environment. Cross-reference datasheet revision numbers to ensure pinout and electrical characteristics align with design specifications.

Selection Notes

Select this component when dual independent J-K flip-flops are required with positive-edge triggering. It is suitable for designs needing direct TTL/CMOS interfacing without additional level shifting. Consider the 74HCT109 variant if strict TTL input voltage levels are necessary instead of CMOS-compatible thresholds. Evaluate the SOIC-16 package constraints against PCB space requirements and thermal dissipation needs.

Part Context

This part belongs to the 74HC family of high-speed CMOS logic devices. It is functionally identical to the LS/ALS109 in pinout but offers improved speed and lower power consumption typical of HC technology. The device is widely used in general-purpose digital electronics where reliable state retention and simple control logic are prioritized over ultra-high-speed switching applications.

Replacement Considerations

The IN74HC109AD from IK Semicon is documented as having an identical pinout and function. Other compatible parts include generic 74HC109 variants from manufacturers like Silicon Supplies, provided they meet the same voltage and interface requirements.