Texas Instruments SN74LV123APWG4

Overview

SN74LV123APWG4 from Texas Instruments is a dual retriggerable monostable multivibrator IC with Schmitt-trigger inputs, operating from 2 V to 5.5 V supply, delivering ≤11 ns propagation delay at 5 V, ±1% pulse-duration matching between channels, and programmable output pulse width up to 100% duty cycle via external R/C network - used for edge-sensitive timing control in digital interrupt conditioning and signal debouncing circuits.

For engineers reviewing the SN74LV123APWG4 datasheet, SN74LV123APWG4 pinout, SN74LV123APWG4 application, or SN74LV123APWG4 equivalent, key selection criteria include its dual-channel retriggerability, Ioff partial-power-down support, mixed-mode voltage tolerance on all I/Os, and guaranteed glitch-free power-up reset - critical for embedded microcontroller interface timing integrity.

Technical Context

The SN74LV123APWG4 integrates two independent monostable multivibrators, each triggered by rising- or falling-edge logic on A/B inputs with Schmitt hysteresis (≥0.3×VCC), enabling robust operation with slow/noisy signals. Pulse duration is set externally via Rext/Cext network, with tw = K × RT × CT where K = 1.0 for CT ≥ 1000 pF.

Each channel supports three trigger modes: (1) 1A↓ with 1B = L, (2) 1B↑ with 1A = H, or (3) 1CLR↑ while 1A = L and 1B = H. The overriding 1CLR input forces immediate Q/Q output termination, and Ioff circuitry isolates outputs during power-down to prevent backflow current.

Key Specifications

Pinout & Package

TSSOP-16 package (6.40 mm × 5.00 mm), lead pitch 0.65 mm, moisture sensitivity level 1 - suitable for high-density PCB layouts and automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC123DR and 74LVC123APW, the SN74LV123APWG4 uniquely combines 5.5 V tolerance, Schmitt-trigger noise immunity, and Ioff power-down protection - making it the sole option for robust, mixed-voltage, hot-pluggable timing in industrial and automotive ECUs.

Availability

SN74LV123APWG4 is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74LV123APWG4 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 timing and interface ICs.

The SN74LV123A product line was designed for precision edge-triggered timing in mixed-voltage embedded systems - targeting applications demanding retriggerable pulse generation, noise-immune inputs, and safe power-down behavior.

FAQ

What is the minimum external timing capacitance supported by SN74LV123APWG4?

The SN74LV123APWG4 imposes no lower limit on Cext value. For capacitors <1000 pF, the multiplier factor K deviates from 1.0 and must be determined from Figure 3 in the datasheet. At Cext = 28 pF and Rext = 2 kΩ, typical pulse width is 240 ns at VCC = 3.3 V - confirming reliable operation down to tens of picofarads.

Does SN74LV123APWG4 support both rising- and falling-edge triggering on the same input pin?

Yes. SN74LV123APWG4 supports edge-selectable triggering per channel: 1A and 2A respond to falling edges when the corresponding B input is held low; 1B and 2B respond to rising edges when the corresponding A input is held high. This dual-edge flexibility is inherent to the internal gated logic architecture.

Can SN74LV123APWG4 operate with VCC = 2.5 V while accepting 5 V inputs?

Yes. SN74LV123APWG4 supports mixed-mode voltage operation: inputs tolerate 0–5.5 V regardless of VCC level. At VCC = 2.5 V, VIH = 1.75 V and VIL = 0.75 V, so a 5 V logic high is safely recognized - enabling direct connection to legacy 5 V peripherals without level shifters.

How does the Ioff feature protect SN74LV123APWG4 during partial power-down?

When VCC = 0 V, the Ioff circuitry in SN74LV123APWG4 disables all outputs and places them in high-impedance state - preventing current backflow from live I/O lines (e.g., 3.3 V buses) into the unpowered device. This avoids latch-up and ensures safe operation in multi-rail power sequencing scenarios.

What is the guaranteed pulse-width matching between the two channels of SN74LV123APWG4?

SN74LV123APWG4 guarantees ±1% output pulse-duration variation (Δtw) between Q and Q outputs under identical R/C conditions and temperature - measured per datasheet Section 7.9, Table 7. This tight matching enables precise dual-channel timing for synchronous enable/disable or differential signaling.