STMicroelectronics M74HC109B1R

Overview

M74HC109B1R from STMicroelectronics is a high-speed CMOS dual J-K flip-flop with asynchronous preset and clear, designed for synchronous edge-triggered logic control in digital state machines. It operates from 2V to 6V, delivers 67 MHz max clock frequency (typ. at VCC = 6V), features symmetrical 4 mA output drive, and supports industrial temperature range (–55°C to +125°C). Used in clock-domain synchronization and register-based control circuits.

For engineers reviewing the M74HC109B1R datasheet, M74HC109B1R pinout, M74HC109B1R application, or M74HC109B1R equivalent, key selection criteria include propagation delay matching (tPLH/tPHL ≈ 13–26 ns at 6V), low ICC (2 µA max at 25°C), noise immunity (VNIH/VNIL = 28% VCC min), and DIP-16 package compatibility with legacy 74-series layouts.

Technical Context

The M74HC109B1R implements two independent edge-triggered J-K flip-flops, each with active-low asynchronous preset (1PR/2PR) and clear (1CLR/2CLR) inputs that override clock and data. Its C2MOS silicon gate process enables rail-to-rail input thresholds and balanced rise/fall propagation delays (tPLH ≅ tPHL).

It supports positive-edge clocking only; J and K inputs determine toggle, set, reset, or hold behavior on each rising CK transition. All inputs include ESD protection diodes, and outputs meet 4 mA sink/source capability with defined VOL/VOH across VCC = 2–6 V and full temperature range.

Key Specifications

Pinout & Package

Package: Plastic DIP-16 (0.300" wide), JEDEC MS-001, body dimensions 20.0 × 8.5 × 3.3 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC109N and CD74HC109E, the M74HC109B1R offers the highest fMAX (67 MHz), lowest ICC (2 µA), and tightest propagation delay matching - making it optimal for timing-critical, low-power, and high-reliability implementations.

Availability

M74HC109B1R is available at Aetrix Electronics and suitable for industrial counter modules, automotive body control units, and legacy PLC I/O expansion requiring stable component supply across extended temperature and long product lifecycles.

Supply support for M74HC109B1R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in microcontrollers, power management, analog, and discrete components for industrial, automotive, and consumer markets.

The M74HC109B1R belongs to ST's high-speed CMOS logic family, engineered for pin- and function-compatible upgrades of legacy TTL logic in mission-critical control and timing applications.

FAQ

What is the maximum clock frequency supported by M74HC109B1R at 3.3 V supply?

At VCC = 3.3 V, the M74HC109B1R supports a maximum clock frequency of 21 MHz (min) and 30 MHz (typ.) per AC specifications. This is derived from the fMAX table on page 5 of the datasheet, where VCC = 4.5 V yields 59 MHz typ., and interpolation confirms 3.3 V operation remains functional within industrial timing budgets.

Can M74HC109B1R operate with a 2.5 V supply in battery-powered applications?

Yes - the device is fully specified down to VCC = 2.0 V. At 2.5 V, VOH is guaranteed ≥2.3 V and VOL ≤0.1 V (IO = 20 µA), supporting interface with 2.5 V logic families. Propagation delay increases to ~190 ns (max), and fMAX drops to ~17 MHz (typ.), which remains viable for low-speed state retention tasks.

Are the preset and clear inputs truly asynchronous and independent per flip-flop?

Yes - pins 1/15 (1CLR/2CLR) and 5/11 (1PR/2PR) operate asynchronously and independently. Each pair controls only its respective flip-flop; asserting 1CLR does not affect FF2, and vice versa. No internal arbitration or priority logic exists between preset and clear - the last asserted low input determines final state.

Does M74HC109B1R require external pull-up or pull-down resistors on J, K, or clock inputs?

No - all inputs have CMOS-compatible high-impedance structure with built-in ESD protection diodes. Floating inputs are not permitted due to undefined logic state; however, external biasing is unnecessary if driven by compatible logic sources. Unused J/K inputs must be tied to VCC or GND to prevent oscillation or increased ICC.