Nexperia USA Inc. 74AHC123AD,118

Overview

74AHC123AD,118 from Nexperia is a dual retriggerable monostable multivibrator with independent reset inputs, designed for precise pulse generation and extension in digital timing circuits. It operates from 2.0 V to 5.5 V, supports CMOS-level inputs, delivers propagation delays as low as 5.1 ns (VCC = 5 V, CL = 15 pF), and enables programmable pulse widths up to 1.15 ms using external REXT/CEXT networks. It is used in industrial control sequencers, power supply fault timers, and debounce circuits requiring long, extendable output pulses.

For engineers reviewing the 74AHC123AD,118 datasheet, 74AHC123AD,118 pinout, 74AHC123AD,118 application, or 74AHC123AD,118 equivalent, this device offers retriggerable pulse extension, direct asynchronous reset, Schmitt-triggered inputs for noise immunity, and overvoltage-tolerant inputs up to 5.5 V-critical for mixed-voltage system interfacing and robust edge-sensitive timing.

Technical Context

The 74AHC123AD,118 implements two independent monostable circuits, each with dual edge-triggered inputs (nA: negative-edge, nB: positive-edge), a dedicated reset input (nRD) that terminates output pulses on LOW-going transitions, and complementary active-HIGH (nQ) and active-LOW (nQ) outputs. Pulse width is externally set via REXT and CEXT components connected to pins nREXT/CEXT and nCEXT, with tW ≈ CEXT × REXT for CEXT ≥ 10 nF.

Each circuit features Schmitt-trigger inputs for high noise immunity, overvoltage tolerance up to 5.5 V on all inputs (enabling level translation), and operation across -40 °C to +125 °C. The device supports 100% duty-cycle extension via retriggering and guarantees propagation delays under 15.5 ns at 5 V/50 pF load, making it suitable for deterministic timing in real-time embedded systems.

Key Specifications

Pinout & Package

74AHC123AD,118 is housed in a plastic SO16 (SOT109-1) package: 16-pin small outline, 3.9 mm body width, gull-wing leads, RoHS-compliant. Pin 1 index located at top-left corner; pin 8 is GND, pin 16 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74AHCT123AD,118, the 74AHC123AD,118 provides superior noise immunity and wider input voltage margins; compared with SN74LVC1G123DBVR, it delivers dual-channel retriggerable functionality essential for complex timing coordination-making it the only drop-in solution for extendable pulse generation in industrial and automotive designs.

Availability

74AHC123AD,118 is available at Aetrix Electronics and suitable for industrial motor control, automotive body electronics, power supply sequencing, and sensor interface applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 74AHC123AD,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 logic, discrete, and MOSFET solutions optimized for efficiency, reliability, and miniaturization in automotive, industrial, and consumer electronics.

The 74AHC123AD,118 belongs to Nexperia's advanced AHC logic family-designed specifically for low-power, high-speed, mixed-voltage digital timing applications where precision, noise immunity, and extended temperature operation are mandatory.

FAQ

What is the minimum recommended CEXT value for stable operation?

The datasheet specifies no minimum CEXT limit, but stability requires CEXT ≥ 10 nF for predictable tW = CEXT × REXT behavior. For values below 10 nF, pulse width deviates from linear scaling due to internal parasitic capacitance; use CEXT ≥ 28 pF with REXT = 2 kΩ for sub-200 ns pulses, verified in dynamic test conditions.

Can 74AHC123AD,118 operate with VCC = 2.5 V?

Yes-VCC is rated from 2.0 V to 5.5 V. At 2.5 V, VIH = 1.75 V and VIL = 0.9 V (per static characteristics table), propagation delay increases to ~20.6 ns (CL = 15 pF), and output drive reduces to ±4 mA. All timing and logic functions remain fully specified across this range.

How should unused inputs be terminated?

Unused inputs (e.g., 1A, 1B, 1RD if only one monostable is used) must be tied to VCC or GND-not left floating-to prevent unintended triggering and excessive ICC. Schmitt-trigger inputs reduce sensitivity, but DC termination is mandatory per Nexperia design guidelines to avoid oscillation or increased power consumption.

Is the 74AHC123AD,118 pin-compatible with older 74LS123 variants?

No-74AHC123AD,118 uses SO16 (SOT109-1) packaging with different pin assignments (e.g., 1CEXT at pin 14, 1REXT/CEXT at pin 15) versus 74LS123's 16-pin DIP layout. Electrical behavior also differs: LS123 lacks retriggerability, has TTL thresholds, and no overvoltage tolerance. Direct replacement requires PCB redesign and logic-level validation.