Texas Instruments CD74HCT109MG4

Overview

CD74HCT109MG4 from Texas Instruments is a dual positive-edge-triggered J-K flip-flop with asynchronous active-low set (S) and reset (R) inputs, operating at 4.5V–5.5V supply voltage, delivering 54MHz maximum clock frequency at V_CC = 5V and C_L = 15pF, and rated for -55°C to +125°C industrial/military temperature range. It serves as a synchronous state-storage element in digital control logic, serial data registers, and counter stages.

For engineers reviewing the CD74HCT109MG4 datasheet, CD74HCT109MG4 pinout, CD74HCT109MG4 application, or CD74HCT109MG4 equivalent, key selection considerations include its LSTTL-compatible input thresholds (V_IL ≤ 0.8V, V_IH ≥ 2.0V), balanced propagation delay (17ns typical CP→Q at 5V/15pF), Schmitt-trigger clock inputs, and SOIC-16 packaging for high-reliability embedded timing circuits.

Technical Context

The CD74HCT109MG4 implements two independent edge-triggered J-K flip-flops sharing no internal coupling; each features separate J, K, CP, S, and R terminals with non-overlapping asynchronous control priority over clocked operation. Its HCT logic family ensures direct compatibility with legacy TTL signal levels while maintaining CMOS power efficiency.

State transitions occur on the low-to-high clock edge; simultaneous active-low S and R force both Q and Q̅ outputs high, but simultaneous deassertion of S and R yields undefined outputs per truth table specification. Propagation delays are tightly matched between Q and Q̅ outputs (±2ns typical), supporting reliable complementary timing in feedback loops and toggle configurations.

Key Specifications

Pinout & Package

CD74HCT109MG4 is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package with 1.27mm lead pitch, JEDEC MS-012AC compliant, moisture sensitivity level 1 (unlimited floor life at <30°C/60% RH), RoHS-compliant NiPdAu finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual J-K flip-flop applications.

Compared with CD74HCT109MG4, SN74HCT109D offers higher speed and longer-term availability, while CD74HC109MG4 provides wider voltage flexibility at the cost of TTL compatibility - selection depends on whether legacy interface assurance or supply scalability is prioritized.

Availability

CD74HCT109MG4 is available at Aetrix Electronics and suitable for industrial automation controllers, aerospace flight computers, automotive engine management units, and military communication subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HCT109MG4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions, with decades of heritage in high-reliability logic families and military-grade qualification programs.

The CD74HCT109MG4 belongs to TI's CD74HCT logic series designed specifically for seamless integration into legacy TTL-based systems while delivering CMOS power efficiency and extended temperature resilience.

FAQ

What is the maximum clock frequency supported by CD74HCT109MG4?

The CD74HCT109MG4 supports a maximum clock frequency of 54MHz when operated at V_CC = 5V with a 15pF load capacitance and ambient temperature of 25°C. This value decreases to 18MHz at the full -55°C to +125°C operating range per switching specifications. The device's Schmitt-trigger clock inputs help maintain reliable edge detection even with slower rise times.

Does CD74HCT109MG4 support direct connection to standard TTL outputs?

Yes, CD74HCT109MG4 is explicitly designed for direct LSTTL input compatibility: its input thresholds are V_IL ≤ 0.8V (max) and V_IH ≥ 2.0V (min) at V_CC = 4.5V–5.5V, matching standard TTL logic levels. No external level-shifting circuitry is required when driven by 74LS or 74F series outputs.

What happens when both set and reset inputs are asserted simultaneously on CD74HCT109MG4?

When both S and R inputs are low simultaneously on CD74HCT109MG4, both Q and Q̅ outputs are forced high - a defined, predictable state. However, if both S and R transition from low to high at the same time, the resulting output state is unpredictable and unstable per the datasheet truth table note; designers must avoid this condition using external synchronization logic.

Is CD74HCT109MG4 compatible with 3.3V logic systems?

No, CD74HCT109MG4 requires a 4.5V–5.5V supply and is not guaranteed to operate correctly with 3.3V inputs or outputs. For 3.3V systems, consider the pin-compatible CD74HC109MG4 (2V–6V supply, CMOS thresholds) or SN74LVC109D (3.3V-tolerant, 1.65V–5.5V supply), both requiring verification of interface voltage translation.

What package type and lead finish does CD74HCT109MG4 use?

CD74HCT109MG4 uses a 16-pin SOIC (D package) with 1.27mm lead pitch, RoHS-compliant NiPdAu lead finish, and moisture sensitivity level 1 (MSL-1). It is supplied in tube packaging with 40 units per tube, and the "G4" suffix denotes TI's green (halogen-free) manufacturing standard per JS709B.