Nexperia USA Inc. 74HC4538DB,112

Overview

74HC4538DB,112 from Nexperia is a dual retriggerable precision monostable multivibrator in SO16 package, delivering ±0.2 % pulse width stability over temperature, 0.7 × R_EXT × C_EXT timing accuracy, and independent rising/falling-edge triggering per channel for precise pulse generation in timing-critical digital systems.

For engineers reviewing the 74HC4538DB,112 datasheet, 74HC4538DB,112 pinout, 74HC4538DB,112 application, or 74HC4538DB,112 equivalent, this device supports high-precision one-shot timing with Schmitt-trigger inputs, separate active-low reset per channel, and external RC programmability - critical for pulse shaping, debouncing, delay generation, and event synchronization in industrial control and instrumentation.

Technical Context

The 74HC4538DB,112 implements two independent monostable circuits, each with dual trigger inputs (nA for falling-edge, nB for rising-edge), dedicated active-low reset (nCD), complementary outputs (nQ/nQ), and external timing pins (nREXT/CEXT and nCEXT) that directly set pulse width via R_EXT and C_EXT.

Its linear design ensures predictable 0.7 × R_EXT × C_EXT output pulse width (T_W) across -40 °C to +125 °C, while Schmitt-trigger inputs tolerate slow signal edges and clamp diodes enable overvoltage-safe interfacing with current-limiting resistors.

Key Specifications

Pinout & Package

74HC4538DB,112 uses the SOT109-1 (SO16) plastic small outline package: 16-pin, 3.9 mm body width, surface-mount, JEDEC MS-012 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC4538D,112 and 74HC4538PW,118, the 74HC4538DB,112 offers identical core functionality but is optimized for automated placement with specific tape-and-reel dimensions - making it ideal for high-volume SMT lines requiring verified feeder compatibility and reduced setup time.

Availability

74HC4538DB,112 is available at Aetrix Electronics and suitable for industrial sensor interfaces, power supply sequencing, motor control fault detection, and digital communication pulse shaping requiring stable component supply across extended temperature ranges.

Supply support for 74HC4538DB,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, discrete, and MOSFET solutions, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.

The 74HC4538 belongs to Nexperia's HC logic family - designed specifically for low-power, wide-supply-voltage digital timing and signal conditioning in harsh-environment applications demanding robust ESD tolerance and thermal stability.

FAQ

What is the minimum external timing resistor value supported by the 74HC4538DB,112?

The datasheet specifies a minimum R_EXT of 2 kΩ at V_CC = 5.0 V. Using lower values risks excessive current through the internal timing node, potentially degrading pulse width accuracy and increasing power dissipation beyond rated limits. For sub-2 kΩ timing, consider the 74HCT4538 variant with TTL-compatible thresholds.

Can both trigger inputs (nA and nB) be used simultaneously on the same channel?

Yes - nA (falling-edge) and nB (rising-edge) are logically OR'd internally per channel. A valid trigger occurs on either edge, enabling single-channel response to bidirectional signal transitions without external logic. This is confirmed in the function table (Table 3) and timing diagram (Fig. 5).

Does the 74HC4538DB,112 require external pull-up or pull-down resistors on its trigger inputs?

No - the Schmitt-trigger inputs have built-in hysteresis and defined switching thresholds (VIH/VIL per Table 6). External resistors are only needed when interfacing to voltages exceeding V_CC, leveraging the internal clamp diodes with current-limiting resistors per Figure 10 guidance.

How does the retrigger time (t_rtrig) vary with external timing components?

t_rtrig = 55 ns + C_EXT/(4.5 × V_CC) per datasheet (Table 7). For example, with C_EXT = 100 nF and V_CC = 5 V, t_rtrig ≈ 55 ns + 4.4 ns = 59.4 ns - meaning the device accepts new triggers no sooner than this interval after the prior edge, ensuring stable pulse extension behavior.