NXP Semiconductors 74HCT423DB,112

Overview

74HCT423DB,112 from Nexperia is a dual retriggerable monostable multivibrator IC with independent reset inputs, designed for precise pulse generation and extension in timing-critical digital systems. It supports 4.5 V to 5.5 V supply operation, delivers propagation delays as low as 19 ns (VCC = 6.0 V), and enables programmable output pulse widths via external REXT/CEXT networks - used in industrial control sequencers, debounce circuits, and programmable delay generators.

For engineers reviewing the 74HCT423DB,112 datasheet, 74HCT423DB,112 pinout, 74HCT423DB,112 application, or 74HCT423DB,112 equivalent, key selection criteria include its retriggerable pulse extension capability, Schmitt-triggered A/B inputs for noise immunity, direct active-LOW reset per channel, and DHVQFN16 package compatibility with AOI-solder-joint inspection.

Technical Context

The 74HCT423DB,112 implements two independent monostable multivibrators, each with dual-edge trigger inputs (1A/2A negative-edge, 1B/2B positive-edge) and dedicated active-LOW reset (1RD/2RD). Pulse width is externally set by resistor-capacitor networks connected to pins 7/15 (2REXT/CEXT, 1REXT/CEXT) and 6/14 (2CEXT, 1CEXT), enabling adjustable timing from nanoseconds to microseconds.

Its TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 4.5 V) ensure interoperability with legacy 5 V logic families, while Schmitt-trigger action on A/B inputs (but not RD) provides hysteresis for robust edge detection on slow-rising signals - critical in mechanical switch interfaces and noisy industrial environments.

Key Specifications

Pinout & Package

DHVQFN16 package (SOT763-1), 2.5 × 3.5 × 0.85 mm body, side-wettable flanks for automated optical inspection of solder joints.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HCT423D,118 and SN74LV423AD, the 74HCT423DB,112 offers superior manufacturability via AOI-ready DHVQFN packaging and tighter propagation delay consistency across temperature - making it optimal for high-reliability industrial timing where solder joint inspection and timing precision are critical.

Availability

74HCT423DB,112 is available at Aetrix Electronics and suitable for industrial control sequencers, programmable delay generators, motor start sequencers, and watchdog timeout extenders requiring stable component supply across extended temperature ranges and high-volume production cycles.

Supply support for 74HCT423DB,112 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 focused on high-volume, high-reliability logic, analog, and discrete components - delivering performance-optimized solutions for automotive, industrial, and consumer markets.

The 74HCT423 family targets robust, retriggerable timing functions in noise-prone environments, emphasizing Schmitt-trigger noise immunity, wide operating temperature support, and AOI-compatible packaging for automated manufacturing.

FAQ

What is the minimum pulse width achievable with the 74HCT423DB,112?

The 74HCT423DB,112 achieves a minimum pulse width of 75 ns under test conditions (VCC = 5.0 V, REXT = 5 kΩ, CEXT = 0 pF). This value is measured from nA/nB trigger to nQ/nQ transition and reflects the device's intrinsic propagation delay plus output transition time - critical for high-frequency timing strobes and narrow enable pulses in digital instrumentation.

How does the retrigger function work on the 74HCT423DB,112?

The 74HCT423DB,112 supports retriggering via either 1A/2A (negative-edge) or 1B/2B (positive-edge) inputs. When a new trigger arrives before the current pulse expires, the output pulse width resets and extends - allowing continuous pulse stretching. The minimum retrigger time is 110 ns (VCC = 5.0 V, REXT = 5 kΩ, CEXT = 0 pF), ensuring reliable extension without race conditions in the 74HCT423DB,112.

Can the 74HCT423DB,112 operate with a 3.3 V supply?

No - the 74HCT423DB,112 is an HCT-family device with TTL-compatible input thresholds and is specified only for 4.5 V to 5.5 V operation. At 3.3 V, VIH (2.0 V min) and VOL (0.4 V max) margins degrade significantly, risking unreliable triggering and output logic levels. For 3.3 V systems, consider the 74LVC423 or SN74LV423AD instead of the 74HCT423DB,112.

What is the purpose of the side-wettable flanks on the 74HCT423DB,112 package?

The side-wettable flanks on the 74HCT423DB,112's DHVQFN16 package (SOT763-1) expose solderable metal along the vertical edges of each terminal, enabling automated optical inspection (AOI) systems to verify solder joint integrity on bottom-mounted pins. This feature directly supports zero-defect manufacturing goals in industrial electronics production where the 74HCT423DB,112 is deployed.

How should the CEXT pins be connected for optimal noise performance in the 74HCT423DB,112?

Per Nexperia's datasheet Figure 11, the 1CEXT and 2CEXT pins (6 and 14) of the 74HCT423DB,112 must be connected directly to the GND pin (8) externally - not left floating or tied only through the capacitor. This shunt path minimizes noise coupling into the timing network and stabilizes the capacitor discharge path, preventing erratic pulse width variation in electrically noisy industrial enclosures where the 74HCT423DB,112 is commonly applied.