Texas Instruments CD74HC4538M96G4

Overview

CD74HC4538M96G4 from Texas Instruments is a dual retriggerable/resettable monostable multivibrator in 16-pin SOIC package, operating from 2V to 6V with ±25mA output drive, Schmitt-trigger inputs on A/B, and independent trigger/reset propagation delays unaffected by external timing components RX/CX. It delivers precise pulse widths (e.g., 0.63–0.81 ms with RX=10kΩ, CX=0.1µF) for timing-critical control logic in industrial sequencers and power-supply supervisors.

For engineers reviewing the CD74HC4538M96G4 datasheet, CD74HC4538M96G4 pinout, CD74HC4538M96G4 application, or CD74HC4538M96G4 equivalent, key selection criteria include its retriggerable mode operation, wide -55°C to +125°C temperature range, dual-section independence, buffered Q/Q outputs, and compatibility with both leading- and trailing-edge triggering - all critical for deterministic timing in embedded control systems.

Technical Context

The CD74HC4538M96G4 implements two independent monostable circuits, each with separate A (leading-edge), B (trailing-edge), R (reset), RX, and CX terminals. Its internal architecture uses Schmitt-trigger input stages and CMOS logic gates to ensure noise immunity and stable edge detection across voltage rails.

Propagation delay (tPLH/tPHL) remains constant at 43–75 ns over VCC = 2–6V and temperature (-55°C to 125°C), and retrigger time (trT) is fixed at ≤175 ns - both independent of RX and CX values. Pulse width τ is calculated as τ ≈ 0.7 × RX × CX, with RX ≥ 5kΩ and CX ≥ 0 pF.

Key Specifications

Pinout & Package

CD74HC4538M96G4 is housed in a 16-pin SOIC (D) package, 7.5 mm × 10.3 mm footprint, 2.00 mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-1, tape-and-reel packaging (2500 units/reel).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC4538M96 and CD74HCT4538M96, the CD74HC4538M96G4 provides wider supply range (2–6V vs. 4.5–5.5V), lower ICC (≤160 µA vs. ≤160 µA but higher active current), and enhanced RoHS traceability - making it optimal for modern mixed-voltage industrial designs requiring long-term component availability.

Availability

CD74HC4538M96G4 is available at Aetrix Electronics and suitable for industrial motor control, power supply sequencing, and automotive body electronics requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC4538M96G4 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 delivering analog and embedded processing solutions, with over 90 years of innovation in precision timing, logic, and power management ICs.

The CD74HC4538M96G4 belongs to TI's HC-series high-speed CMOS logic family, designed specifically for robust, low-power, wide-temperature monostable timing in industrial automation, automotive subsystems, and instrumentation where deterministic pulse generation is mission-critical.

FAQ

What is the minimum external timing resistor value supported by the CD74HC4538M96G4?

The CD74HC4538M96G4 requires a minimum external timing resistor RX of 5 kΩ, as specified in the Absolute Maximum Ratings and confirmed in the Functional Description section. Using lower values may cause excessive current into pins 2 or 14 (1RXCX/2RXCX), exceeding the 30 mA absolute maximum rating and risking device damage or timing inaccuracy. Always verify RX ≥ 5 kΩ in all operating conditions including worst-case temperature and voltage.

Can the CD74HC4538M96G4 operate reliably at 2.0V supply voltage?

Yes, the CD74HC4538M96G4 is fully specified for operation down to 2.0V, with validated performance across -55°C to +125°C. At 2V, propagation delay is ≤375 ns, output drive remains ±25mA, and input thresholds scale proportionally (VIH = 1.5V min, VIL = 0.5V max). This makes CD74HC4538M96G4 suitable for single-cell LiFePO₄ or alkaline battery-powered systems where headroom is constrained.

How does the retriggerable mode function differ from non-retriggerable mode in the CD74HC4538M96G4?

In retriggerable mode, each new trigger pulse (on A or B) extends the output pulse width by a full τ interval - ideal for maintaining an active signal during recurring events like encoder pulses. In non-retriggerable mode (achieved by connecting Q to B for A-triggering or Q to A for B-triggering), only the first trigger initiates the pulse; subsequent triggers are ignored until completion. This distinction is fundamental to CD74HC4538M96G4's use in watchdog supervision versus one-shot event capture.

What is the purpose of the Schmitt-trigger inputs on pins A and B of the CD74HC4538M96G4?

The Schmitt-trigger inputs on pins A and B of the CD74HC4538M96G4 provide hysteresis (typically ~0.4V at VCC=5V), ensuring clean, noise-immune edge detection on slow-rising or electrically noisy signals - such as those from mechanical switches, hall-effect sensors, or long PCB traces. This prevents multiple false triggers and guarantees single, deterministic pulse initiation per valid edge transition, a core requirement in CD74HC4538M96G4's timing-critical applications.

Is the CD74HC4538M96G4 pin-compatible with the CD74HCT4538M96?

Yes, the CD74HC4538M96G4 is pin-compatible with the CD74HCT4538M96 - both use identical 16-pin SOIC (D) packages and share identical pin assignments for VCC, GND, A/B/R/Q/Q/RXCX/CX terminals. However, they differ in logic family (HC vs. HCT), supply range (2–6V vs. 4.5–5.5V), and input threshold compatibility (CMOS vs. TTL). No PCB changes are required for substitution, but system-level voltage and interface compatibility must be verified before replacement.