Texas Instruments CD74HC109MG4

Overview

CD74HC109MG4 from Texas Instruments is a dual positive-edge-triggered J-K flip-flop with asynchronous active-low set (S) and reset (R) inputs, operating across 2V–6V supply range, delivering 54MHz maximum clock frequency at VCC = 5V with CL = 15pF, and supporting industrial temperature range of –55°C to +125°C. It serves as a synchronous storage element in digital control logic, state machines, and clock-domain synchronization circuits.

For engineers reviewing the CD74HC109MG4 datasheet, CD74HC109MG4 pinout, CD74HC109MG4 application, or CD74HC109MG4 equivalent, key selection considerations include its Schmitt-trigger clock inputs for noise immunity, balanced propagation delay (14ns typical at 5V), LSTTL fanout capability (10 loads), and compatibility with both CMOS and TTL-level input thresholds.

Technical Context

The CD74HC109MG4 implements two independent edge-triggered J-K flip-flops sharing no internal coupling - each responds solely to its own CP, J, K, S, and R signals. Its asynchronous S and R override clocked operation and force Q/Q outputs high or low regardless of clock phase.

Each flip-flop features Schmitt-trigger clock inputs enabling robust operation under slow-rising or noisy clock edges, and exhibits matched tPLH/tPHL propagation delays (±2ns typical mismatch) with transition times under 19ns at 5V/CL=50pF - critical for deterministic timing in sequential logic design.

Key Specifications

Pinout & Package

CD74HC109MG4 is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package with standard JEDEC MS-012AC footprint (5.3mm width, 1.27mm pitch). Pin 1 is located at the top-left corner marked by a beveled edge or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC109MG4, SN74HC109DR offers identical electrical performance with enhanced manufacturing support, while MC74HC109ADTR2G trades 4 MHz speed for broader supply tolerance and alternate supply-chain assurance - neither is pin-compatible with CD74HC109MG4's legacy tube packaging but shares the same SOIC-16 footprint and logic behavior.

Availability

CD74HC109MG4 is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC109MG4 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 over 50 years of innovation in high-reliability digital ICs.

The CD74HC109MG4 belongs to TI's legacy HC logic family - designed for robust, low-power, wide-supply-range digital control in mission-critical industrial and defense systems where timing predictability and environmental resilience are paramount.

FAQ

What is the maximum clock frequency supported by CD74HC109MG4?

The CD74HC109MG4 supports a maximum clock frequency of 54 MHz when operated at VCC = 5V with a 15 pF load capacitance and ambient temperature of 25°C. This specification is validated per the official Texas Instruments datasheet SCHS140E. At 2V supply, fMAX drops to 4 MHz; at 6V, it reaches 23 MHz over the full –55°C to +125°C range. The actual achievable frequency in a given design depends on trace capacitance, driver strength, and signal integrity.

Does CD74HC109MG4 have Schmitt-trigger inputs on all pins?

No - only the clock inputs (1CP and 2CP) feature Schmitt-trigger circuitry in the CD74HC109MG4. The J, K, S, and R inputs are standard CMOS inputs without hysteresis. This design ensures noise immunity specifically on the timing-critical clock path while maintaining conventional logic thresholds on control and data inputs for compatibility with standard logic families.

Can CD74HC109MG4 operate reliably at 3.3V supply voltage?

Yes, CD74HC109MG4 is fully specified to operate from 2V to 6V, including 3.3V nominal systems. At VCC = 3.3V, it delivers VIH(min) = 2.0V, VIL(max) = 1.3V, VOH(min) = 3.15V (CMOS load), and VOL(max) = 0.1V - ensuring solid noise margins and interoperability with 3.3V microcontrollers and FPGAs without level-shifting circuitry.

What happens when both Set and Reset are asserted low simultaneously on CD74HC109MG4?

When both S and R inputs are low simultaneously on either flip-flop in the CD74HC109MG4, both Q and Q̅ outputs are forced high - a defined, stable condition per the truth table. However, if both S and R transition high simultaneously, the resulting output state is unpredictable and unstable (metastable), as explicitly noted in the datasheet. Designers must avoid this condition using proper reset sequencing or external arbitration logic.

Is CD74HC109MG4 RoHS compliant?

Yes, CD74HC109MG4 is RoHS compliant. According to Texas Instruments' Packaging Information Addendum, the part carries "Yes" in the RoHS column and uses NiPdAu (nickel-palladium-gold) lead finish. It meets EU Directive 2011/65/EU requirements and is suitable for use in environmentally regulated commercial and industrial applications.