Texas Instruments CD74HC4538M96E4

Overview

CD74HC4538M96E4 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 pins, 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 fault recovery circuits.

For engineers reviewing the CD74HC4538M96E4 datasheet, CD74HC4538M96E4 pinout, CD74HC4538M96E4 application, or CD74HC4538M96E4 equivalent, key selection factors include its retriggerable edge-triggering capability, wide -55°C to +125°C temperature range, 10 LSTTL fanout, and compatibility with both leading- and trailing-edge input pulses - critical for robust timing in harsh-environment embedded systems.

Technical Context

The CD74HC4538M96E4 implements two independent monostable sections, each with separate A (leading-edge), B (trailing-edge), R (reset), Q/Q̅ outputs, and dedicated RX/CX timing networks. Its internal Schmitt-trigger inputs reject noise, while propagation delays (e.g., 43–75 ns at VCC=6V) remain stable across temperature and supply voltage due to CMOS HC logic architecture.

Timing precision relies on external RX ≥5kΩ and CX ≥0pF, with pulse width τ = 0.7·RX·CX. Retrigger time is independent of CX, enabling reliable multi-pulse synchronization. Unused A inputs must be tied to GND and unused B inputs to VCC; power-up reset ensures deterministic initial state.

Key Specifications

Pinout & Package

CD74HC4538M96E4 uses a 16-pin SOIC (D) package with 1.27 mm pitch, 10.4 mm × 7.4 mm body, and 2.00 mm max height. Pin 1 is marked via corner chamfer or dot; tape-and-reel packaging (2500 pcs/reel) complies with JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC4538M96 (identical base part) and SN74LV4538ADT (LV logic variant), CD74HC4538M96E4 uniquely combines military-grade reliability screening, full 2V–6V operation, and integrated Schmitt-trigger inputs - making it the sole choice for timing-critical industrial and defense systems requiring guaranteed performance across extreme conditions.

Availability

CD74HC4538M96E4 is available at Aetrix Electronics and suitable for industrial sequencing, power-supply fault recovery, test equipment timing, and automotive sensor signal conditioning requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC4538M96E4 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 specializing in analog, embedded processing, and logic ICs, with decades of heritage in high-reliability timing and interface solutions.

The CD74HC4538 series belongs to TI's High-Speed CMOS Logic family, designed specifically for precision timing applications demanding retriggerable monostable behavior, wide temperature operation, and noise-immune input interfaces in industrial, military, and automotive systems.

FAQ

What is the minimum external timing resistor value supported by CD74HC4538M96E4?

The CD74HC4538M96E4 specifies a minimum external timing resistor RX of 5 kΩ. Using lower values risks exceeding the 30 mA maximum current into pins 2 or 14, potentially damaging the internal timing comparator. For pulse widths below ~35 µs, consider using the HCT variant or alternative timing architectures.

Can CD74HC4538M96E4 operate reliably at 2.0V supply voltage?

Yes, CD74HC4538M96E4 is fully specified down to 2.0V supply voltage, with guaranteed propagation delays (max 375 ns), output drive (±25 mA), and Schmitt-trigger hysteresis (30% of VCC). This enables direct integration into 2.0V–2.7V battery-powered instrumentation without level translation.

How does the retriggerable mode function in CD74HC4538M96E4?

In retriggerable mode, CD74HC4538M96E4 extends the output pulse width by one full timing period τ for each new trigger pulse received before the prior pulse expires. This behavior is inherent to the internal state machine and requires no external feedback - unlike non-retriggerable mode which locks the pulse duration after the first trigger.

What is the purpose of the RXCX pin (pins 2 and 14) on CD74HC4538M96E4?

Pins 2 (1RXCX) and 14 (2RXCX) on CD74HC4538M96E4 serve as combined nodes for the external timing resistor (RX) and capacitor (CX), forming the RC network that controls pulse width τ = 0.7·RX·CX. These pins connect directly to internal comparators and discharge transistors - correct routing and low-noise layout are essential for timing accuracy.

Is CD74HC4538M96E4 pin-compatible with CD74HCT4538M96E4?

No, CD74HC4538M96E4 and CD74HCT4538M96E4 are not pin-compatible replacements. While both use the same SOIC-16 package and share identical pin functions, their input thresholds differ: HC requires VIH ≥1.5V (at 2V) while HCT mandates VIH ≥2.0V (at 4.5V–5.5V). Interchanging them may cause logic misreads in mixed-voltage systems.