Texas Instruments SN74AHC123APWRE4

Overview

SN74AHC123APWRE4 from Texas Instruments is a dual retriggerable monostable multivibrator in TSSOP-16 package, operating from 2 V to 5.5 V, featuring Schmitt-trigger inputs (A, B, CLR), edge-triggered logic with active-high/low gating, and external RC-controlled pulse duration up to 1.1 ms. It delivers glitch-free power-up reset, overriding clear functionality, and ±25 mA output drive - used in timing control, debounce, and pulse shaping circuits for industrial PLCs and sensor interface modules.

For engineers reviewing the SN74AHC123APWRE4 datasheet, SN74AHC123APWRE4 pinout, SN74AHC123APWRE4 application, or SN74AHC123APWRE4 equivalent, key selection criteria include retriggerable pulse width accuracy (±1% variation), input hysteresis for slow-edge immunity, low-power AHC logic family compatibility, and TSSOP-16 thermal performance (θ_JA = 108°C/W).

Technical Context

This device implements two independent monostable multivibrators, each triggered by three distinct input combinations: rising edge on B while A is low, falling edge on A while B is high, or high-going CLR with A low/B high. Pulse duration is externally set via R_ext and C_ext, with K-factor dependency on C_ext value (K = 1.0 for ≥1000 pF).

Each circuit includes Schmitt-trigger inputs ensuring jitter-free triggering under slow transitions, overriding CLR that forces Q low regardless of A/B state, and internal power-up reset holding Q low and Q high. Output pulse stability is maintained across temperature (±1% variation) and supply voltage (2–5.5 V), with propagation delays as low as 5.3 ns at V_CC = 5 V.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 4.4 mm × 5.0 mm body, 1.2 mm max height, 0.65 mm lead pitch, RoHS-compliant, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC123APWRE4, SN74AHCT123ADBR offers TTL-compatible inputs at the cost of higher static current, while MC74HC123ADR2G trades timing precision for wider V_CC tolerance and lower unit cost - making SN74AHC123APWRE4 optimal for high-accuracy, low-power, 2–5.5 V retriggerable timing.

Availability

SN74AHC123APWRE4 is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller peripheral timing, and LED control systems requiring stable component supply, RoHS compliance, and TSSOP-16 footprint compatibility.

Supply support for SN74AHC123APWRE4 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 ICs, with over 90 years of innovation in industrial, automotive, and communications electronics.

The SN74AHC123A product line delivers advanced CMOS monostable multivibrators optimized for precision timing, retriggerability, and robust noise immunity in space-constrained industrial control and instrumentation systems.

FAQ

What is the minimum external timing capacitance supported by SN74AHC123APWRE4?

The SN74AHC123APWRE4 supports external timing capacitances as low as 28 pF, validated in switching characteristics tables at V_CC = 5 V with R_ext = 2 kΩ yielding t_w = 240 ns. For C_ext < 1000 pF, the multiplier factor K is voltage- and capacitance-dependent per Figure 9; below 100 pF, K drops below 1.0, requiring design verification using TI's SCLA014 application report.

Can SN74AHC123APWRE4 operate reliably at 2.0 V supply voltage?

Yes, SN74AHC123APWRE4 is fully specified for operation at 2.0 V per recommended conditions: VIH = 1.5 V, VIL = 0.5 V, I_OH/I_OL = ±50 µA, and t_PLH/t_PHL ≤ 24 ns (CL = 15 pF). At 2 V, pulse duration scales linearly with R_ext·C_ext, and propagation delay increases modestly - enabling ultra-low-power timing in energy-harvesting sensor nodes.

How does the overriding clear function interact with retriggering in SN74AHC123APWRE4?

In SN74AHC123APWRE4, asserting CLR high immediately forces Q low and terminates any active output pulse, regardless of ongoing A/B retrigger activity. Once CLR returns low, the multivibrator resumes normal operation and accepts new triggers. This priority-based behavior is confirmed in the FUNCTION TABLE and input/output timing diagram - CLR is asynchronous and dominates all other inputs.

Is SN74AHC123APWRE4 pin-compatible with SN74AHC123APWR?

Yes, SN74AHC123APWRE4 and SN74AHC123APWR share identical TSSOP-16 (PW) package dimensions, pinout, and electrical specifications. The "E4" suffix denotes TI's green RoHS-compliant packaging standard (lead-free, no Sb/Br), while SN74AHC123APWR uses an earlier eco-plan - both are mechanically and electrically interchangeable in existing PCB layouts.

What is the maximum recommended external timing resistance for SN74AHC123APWRE4?

The datasheet specifies R_ext ≥ 1 kΩ for V_CC > 3 V and ≥ 5 kΩ for V_CC = 2 V, but no absolute maximum is defined. Practical limits arise from leakage current and noise susceptibility: TI application note SCLA014 recommends R_ext ≤ 200 kΩ to maintain timing accuracy within ±5% and avoid excessive sensitivity to board leakage. At 200 kΩ and 0.01 µF, t_w ≈ 2 ms is achievable.