Texas Instruments CD74HCT423MT

Overview

CD74HCT423MT from Texas Instruments is a dual retriggerable monostable multivibrator with independent resets, designed for precise pulse generation and timing control in digital systems. It operates from 4.5V to 5.5V, features Schmitt-trigger inputs on both A and B terminals, supports trailing-edge (A) and leading-edge (B) triggering, and delivers buffered Q and Q̅ outputs with output pulse widths adjustable via external RX/CX components (t_W = 0.45·R_XC_X at V_CC = 5V). It is used in industrial control logic, debounce circuits, and programmable delay generators.

For engineers reviewing the CD74HCT423MT datasheet, CD74HCT423MT pinout, CD74HCT423MT application, or CD74HCT423MT equivalent, key selection criteria include its HCT-level LSTTL input compatibility (V_IL ≤ 0.8V, V_IH ≥ 2.0V), wide -55°C to +125°C operating temperature range, retriggerable behavior with reset override capability, and SOIC-16 package suitability for high-reliability embedded timing functions.

Technical Context

The CD74HCT423MT implements two independent monostable multivibrators, each with separate A (trailing-edge), B (leading-edge), and R (active-low reset) inputs. Triggering occurs at defined voltage thresholds-not dependent on input slew rate-due to integrated Schmitt triggers on A and B pins.

Each monostable is retriggerable: an active input edge during an ongoing output pulse extends t_W; a LOW on R terminates the pulse immediately. Pulse width is externally set by R_X and C_X, with minimum R_X = 5 kΩ and C_X = 0 pF; typical t_W = 45 µs when R_X = 10 kΩ and C_X = 10 nF at V_CC = 5V.

Key Specifications

Pinout & Package

CD74HCT423MT is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package with standard 1.27 mm pitch, 10.4 mm × 7.4 mm body size, and 2.00 mm max height per JEDEC MS-012. The package is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HCT123MT, CD74HCT423MT provides deterministic level-sensitive reset control ideal for safety-critical timeout supervision, while SN74HCT123DR offers identical functionality with improved manufacturability and lifecycle support-making it the recommended upgrade path for new designs.

Availability

CD74HCT423MT is available at Aetrix Electronics and suitable for industrial control sequencing, pushbutton debounce circuits, programmable delay generation, and watchdog timer reset supervision requiring stable component supply across extended temperature ranges.

Supply support for CD74HCT423MT 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 company specializing in analog and embedded processing technologies, with leadership in precision timing, power management, and industrial-grade logic.

The CD74HCT423MT belongs to TI's 74HCT logic family, engineered for robust 5V system integration with LSTTL compatibility, wide temperature operation, and reliable retriggerable timing-targeting industrial automation, instrumentation, and safety-critical control applications.

FAQ

What is the maximum operating temperature for CD74HCT423MT?

The CD74HCT423MT is rated for continuous operation from -55°C to +125°C. This extended temperature range is verified per TI's military-grade qualification and supports deployment in harsh environments such as industrial motor drives, avionics subsystems, and under-hood automotive electronics where ambient temperatures exceed commercial-grade limits. The SOIC package maintains thermal integrity across this full range.

Can CD74HCT423MT be used with 3.3V logic systems?

No, CD74HCT423MT requires a supply voltage of 4.5V to 5.5V and is not guaranteed to operate correctly at 3.3V. Its HCT input thresholds (V_IL ≤ 0.8V, V_IH ≥ 2.0V) are optimized for 5V TTL compatibility, and internal circuitry is not characterized below 4.5V. For 3.3V systems, consider the CD74HC423MT (2V–6V operation) or level-shifting interfaces.

How does the retriggering behavior work in CD74HCT423MT?

In CD74HCT423MT, a new active edge on A or B during an ongoing output pulse extends the total pulse width by t_W from that trigger point-enabling dynamic pulse stretching. Retriggering is only effective if the time between successive trigger edges meets the minimum retrigger time (t_rT = 76 ns max at V_CC = 5V, R_X = 10 kΩ, C_X = 0). This behavior is intrinsic to the monostable architecture and requires no external logic.

What is the minimum external timing capacitor value for CD74HCT423MT?

The minimum external timing capacitor (C_X) for CD74HCT423MT is 0 pF-meaning the device can generate pulses using only R_X (with minimum 5 kΩ) and stray capacitance. However, for stable, repeatable timing, TI recommends C_X ≥ 100 pF. At C_X = 10 nF and R_X = 10 kΩ, typical t_W = 45 µs with ±2% matching between the two monostables on the same die.

Is CD74HCT423MT pin-compatible with CD74HC423MT?

Yes, CD74HCT423MT and CD74HC423MT share identical pinout, package (SOIC-16), and functional block diagram. The only differences are electrical: CD74HCT423MT operates at 4.5–5.5V with LSTTL-compatible inputs, while CD74HC423MT operates at 2–6V with CMOS-compatible inputs (V_IL ≤ 1.35V, V_IH ≥ 3.15V at V_CC = 4.5V). Direct substitution is possible only if supply and input logic levels match the selected variant.