Nexperia USA Inc. 74HCT4538PW-Q100,1

Overview

74HCT4538PW-Q100 from Nexperia is a dual retriggerable-resettable precision monostable multivibrator in TSSOP16 package, operating from 4.5 V to 5.5 V over −40 °C to +125 °C. It provides two independent timing channels, each with rising- and falling-edge trigger inputs (nA/nB), active-low direct reset (nCD), complementary outputs (nQ/nQ), and external REXT/CEXT timing control. Output pulse width is precisely defined as TW = 0.7 × REXT × CEXT, with ±0.2 % typical variation over temperature - used in automotive engine control timing, ABS pulse conditioning, and safety-critical sensor debouncing.

For engineers reviewing the 74HCT4538PW-Q100 datasheet, 74HCT4538PW-Q100 pinout, 74HCT4538PW-Q100 application, or 74HCT4538PW-Q100 equivalent, key selection concerns include edge-trigger flexibility (rising/falling), AEC-Q100 Grade 1 qualification, Schmitt-trigger input noise immunity, TTL-compatible input thresholds, and precise external RC-based pulse width control without internal oscillator drift.

Technical Context

This device implements two independent CMOS monostable circuits using linear timing techniques to achieve high pulse width accuracy. Each channel accepts asynchronous triggers on either nA (active-HIGH-to-LOW) or nB (active-LOW-to-HIGH), supports immediate termination via nCD, and delivers matched complementary outputs with propagation delays under 90 ns at 4.5 V.

The timing architecture relies entirely on external REXT and CEXT components connected to dedicated pins (nREXT/CEXT and nCEXT), enabling programmable pulse widths from sub-microsecond to multi-second ranges. Input clamp diodes and Schmitt-trigger inputs ensure robust operation with slow-rising signals and noise-prone automotive environments.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1): plastic thin shrink small outline, 16 leads, body width 4.4 mm, lead pitch 0.65 mm, 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 74HCT4538D-Q100, the PW variant offers superior board density and thermal performance in constrained automotive modules; versus SN74LV4538AQPWRQ1, it delivers tighter pulse width accuracy (±0.2 % vs. ±1.5 % typical) and true external RC programmability essential for calibration-critical timing.

Availability

74HCT4538PW-Q100 is available at Aetrix Electronics and suitable for automotive powertrain control, ABS sensor interface, and body electronics requiring stable component supply across extended temperature and long lifecycle commitments.

Supply support for 74HCT4538PW-Q100 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 MOSFET solutions, with leadership in automotive-grade components and AEC-Q100 qualification infrastructure.

The 74HCT4538-Q100 belongs to Nexperia's automotive-qualified HCT logic family, designed specifically for timing-critical functions in engine management, braking, and chassis control systems where precision, noise immunity, and temperature stability are non-negotiable.

FAQ

What is the minimum external timing capacitor value supported?

The datasheet specifies no lower limit for CEXT, but practical minimums are governed by leakage and parasitic capacitance. For stable sub-microsecond pulses, CEXT ≥ 100 pF is recommended. At 1 nF and 10 kΩ REXT, typical pulse width is 700 μs with ±0.2 % accuracy over temperature.

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

Yes - nA and nB are logically OR'd internally. A valid trigger occurs on either a HIGH-to-LOW transition at nA or a LOW-to-HIGH transition at nB. This allows flexible edge detection from a single signal source without external logic.

How does the reset input (nCD) interact with retriggering?

nCD is asynchronous and dominant: asserting nCD LOW immediately forces nQ LOW and nQ HIGH, terminating any active pulse regardless of ongoing retrigger events. Release of nCD restores normal monostable operation, but does not restart timing unless a new trigger occurs.

Is power-down protection required when using large CEXT values?

Yes - if CEXT > 100 nF, energy stored during operation may discharge through input protection diodes during rapid VCC collapse, risking damage. Nexperia recommends adding a Schottky damping diode (DEXT) between nREXT/CEXT and GND as shown in Figure 10 of the datasheet.