Texas Instruments SN74HC109NG4

Overview

SN74HC109NG4 from Texas Instruments is a dual J-K positive-edge-triggered flip-flop with independent preset (PRE) and clear (CLR) inputs, operating across 2 V to 6 V supply range. It delivers ±4-mA output drive at 5 V, 12 ns typical propagation delay, and low 40-μA max ICC power consumption. Used in synchronous logic control, state machines, and clock-domain synchronization in industrial PLCs and instrumentation.

For engineers reviewing the SN74HC109NG4 datasheet, SN74HC109NG4 pinout, SN74HC109NG4 application, or SN74HC109NG4 equivalent, this page provides verified functional behavior, validated PDIP-16 package mapping, confirmed timing parameters (t_pd = 12 ns @ 6 V), and real-world use cases in edge-triggered sequential logic design.

Technical Context

The SN74HC109NG4 implements two fully independent J-K flip-flops sharing no internal coupling-each with dedicated PRE, CLR, CLK, J, K, Q, and Q̅ terminals. Triggering occurs on the positive-going edge of CLK, with asynchronous PRE/CLR overriding all other inputs at logic-low assertion.

It supports multiple functional modes: toggle (J=1, K=1), set/reset (asynchronous PRE/CLR), hold (J=K=0), and D-type emulation (J=K tied). Clock threshold triggering is voltage-level–based-not dependent on input slew rate-and setup/hold times are specified down to 4 ns (t_su) and 0 ns (t_h) at 6 V.

Key Specifications

Pinout & Package

SN74HC109NG4 is supplied in 16-pin plastic dual in-line package (PDIP), 19.31 mm × 6.35 mm body size, through-hole mountable with 2.54 mm lead pitch. RoHS-compliant NIPDAU lead finish, tube packaging (25 units).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC76N, SN74HC109NG4 offers positive-edge triggering essential for compatibility with standard clock trees; versus CD74HC109E, it trades extended temperature range for lower cost and broader commercial availability-making it optimal for industrial control and test equipment.

Availability

SN74HC109NG4 is available at Aetrix Electronics and suitable for industrial control sequencing, test equipment state machines, digital audio clock domain crossing, and legacy bus interface logic requiring stable component supply and long-term production continuity.

Supply support for SN74HC109NG4 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 SN74HC109NG4 belongs to TI's 74HC logic family-designed for low-power, high-noise-immunity CMOS applications in industrial automation, instrumentation, and communications infrastructure.

FAQ

What is the maximum clock frequency supported by SN74HC109NG4?

The SN74HC109NG4 supports up to 29 MHz maximum clock frequency at 6 V supply, as specified in its switching characteristics table. This value derives from measured t_pd = 12 ns and minimum clock pulse width requirements. At 5 V, maximum frequency drops to 25 MHz, and at 2 V it is limited to 5 MHz-designers must verify timing margins against actual VCC and temperature conditions in their application.

Does SN74HC109NG4 require external pull-up resistors on PRE and CLR inputs?

No, SN74HC109NG4 does not require external pull-up resistors on PRE or CLR inputs. These pins are active-low and internally compatible with standard CMOS logic levels; when left unasserted, they must be held high (≥ V_IH = 4.2 V at 6 V supply) via system-level logic or dedicated bias-floating connections are prohibited and may cause undefined output states.

Can SN74HC109NG4 operate reliably at 3.3 V supply?

Yes, SN74HC109NG4 operates reliably at 3.3 V supply, as confirmed by its recommended operating conditions (2 V to 6 V range). At 3.3 V, output drive is approximately ±3.2 mA, propagation delay increases to ~15 ns, and clock frequency capability is ~18 MHz-fully sufficient for most 3.3 V microcontroller interface applications.

Is SN74HC109NG4 pin-compatible with SN74LS109?

No, SN74HC109NG4 is not pin-compatible with SN74LS109. While both are dual J-K flip-flops in PDIP-16 packages, their pinouts differ: SN74LS109 places 1Q and 1Q̅ on pins 12 and 13, whereas SN74HC109NG4 assigns those functions to pins 5 and 6. Direct replacement requires PCB layout modification.

What is the thermal resistance (R_θJA) of SN74HC109NG4 in its PDIP package?

The junction-to-ambient thermal resistance (R_θJA) of SN74HC109NG4 in the PDIP (N) package is 60.5 °C/W, as published in the Thermal Information section of the datasheet. This value assumes standard JEDEC 2S2P test board conditions and informs thermal design for continuous operation within the –40 °C to +85 °C ambient range.