Nexperia USA Inc. 74AHCT123AD,118

Overview

74AHCT123AD,118 from Nexperia is a dual retriggerable monostable multivibrator with independent reset inputs, TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max), 16-pin SO16 package, and programmable pulse width via external REXT/CEXT networks. It supports 4.5 V to 5.5 V supply operation, delivers sub-15 ns propagation delay at 5 V/50 pF, and enables precise timing control in digital logic interfaces requiring pulse extension or early termination.

For engineers reviewing the 74AHCT123AD,118 datasheet, 74AHCT123AD,118 pinout, 74AHCT123AD,118 application, or 74AHCT123AD,118 equivalent, this device serves as a robust, temperature-stable (–40 °C to +125 °C) timing element for edge-triggered pulse shaping, debouncing, and delay generation where retriggering flexibility and direct reset override are essential.

Technical Context

The 74AHCT123AD,118 implements two independent monostable circuits, each with dual edge-triggered inputs (nA: negative-edge, nB: positive-edge) and a dedicated active-low reset (nRD) that terminates output pulses asynchronously. Pulse width tW is externally set by REXT and CEXT, with typical values ranging from 100 ns (CEXT = 28 pF, REXT = 2 kΩ) to 1.15 ms (CEXT = 0.1 μF, REXT = 10 kΩ) at VCC = 5 V.

Its TTL-level inputs ensure compatibility with legacy 5 V logic families, while overvoltage-tolerant inputs (up to 5.5 V) and Schmitt-trigger action on all inputs provide noise immunity and mixed-voltage interface capability. Each circuit features complementary outputs (nQ and nQ), supporting both active-HIGH and active-LOW timing signals without external inversion.

Key Specifications

Pinout & Package

74AHCT123AD,118 is housed in a plastic small outline package (SO16, SOT109-1) with 16 leads, 3.9 mm body width, and standard 1.27 mm lead pitch. The package is RoHS-compliant and rated for surface-mount reflow assembly per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar monostable multivibrator applications.

Compared with 74AHC123AD,118 and SN74LV123ADR, the 74AHCT123AD,118 offers superior noise immunity and deterministic TTL-level recognition-critical in electrically harsh industrial environments-while maintaining identical pinout and functional behavior.

Availability

74AHCT123AD,118 is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, medical diagnostic equipment, and test instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AHCT123AD,118 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

Nexperia is a global semiconductor expert delivering high-performance, reliable logic, discrete, and MOSFET solutions with focus on efficiency, reliability, and sustainability.

The 74AHCT123AD,118 belongs to Nexperia's industry-standard 74AHCT logic family, designed specifically for robust 5 V TTL-compatible timing and signal conditioning in automotive, industrial, and infrastructure applications.

FAQ

What is the minimum external capacitor value supported for pulse width programming?

The datasheet specifies no lower limit for CEXT - values as low as 28 pF are validated for sub-200 ns pulses at 5 V. Practical minimum is constrained by PCB stray capacitance (~2–5 pF) and stability; use NP0/C0G dielectric for precision. For <100 ns widths, verify layout parasitics and consider integrated alternatives.

Can both monostable circuits be triggered simultaneously without crosstalk?

Yes - circuits 1 and 2 are electrically isolated except for shared VCC and GND. Dynamic testing confirms no measurable coupling (<1 mV) between outputs during simultaneous retriggering. Layout best practice: separate CEXT/REXT networks and local decoupling per circuit improves margin.

Is the nRD pin truly asynchronous, and does it affect both outputs immediately?

Yes - nRD is fully asynchronous and overrides all internal timing states. When nRD transitions LOW, nQ goes HIGH and nQ goes LOW within tPHL(max) = 15.5 ns (VCC = 5.5 V, CL = 50 pF), regardless of ongoing pulse duration or retrigger activity.

How does the device behave when CEXT is left unconnected?

Leaving CEXT floating violates the Absolute Maximum Rating for VI (–0.5 V to +7.0 V) and risks latch-up. The datasheet mandates external grounding of pins 6 (2CEXT) and 14 (1CEXT) if unused. Unconnected CEXT causes undefined pulse width and potential output oscillation due to stray capacitance.