Texas Instruments CD74HC4538QM96Q1

Overview

CD74HC4538QM96Q1 from Texas Instruments is an automotive-qualified dual retriggerable precision monostable multivibrator IC used for fixed-voltage timing control in safety-critical systems. It features independent trigger/reset propagation delays (50 ns typical at 4.5 V), Schmitt-trigger inputs on A/B channels, buffered Q and Q̅ outputs per channel, and operates across 2 V to 6 V supply range with –40°C to +125°C temperature rating.

For engineers reviewing the CD74HC4538QM96Q1 datasheet, CD74HC4538QM96Q1 pinout, CD74HC4538QM96Q1 application, or CD74HC4538QM96Q1 equivalent, key selection considerations include retriggerable timing behavior, external RC timing independence, edge-selectable triggering (rising/falling), automotive AEC-Q100 qualification, and SOIC-16 package compatibility with industrial timing and pulse-shaping circuits.

Technical Context

The CD74HC4538QM96Q1 implements two independent monostable multivibrators, each with separate rising-edge (A) and falling-edge (B) inputs, individual reset (R) terminals, and complementary buffered outputs (Q/Q̅). Timing is set externally via resistor (RX) and capacitor (CX) networks, with output pulse width τ = 0.7 × RX × CX and retrigger time independent of CX value.

Propagation delays from A/B or R inputs to Q/Q̅ outputs are independent of RX and CX values, enabling stable timing across wide RC ranges. Each channel supports both retriggerable and nonretriggerable modes via external feedback, and unused inputs must be tied to VCC or GND to prevent floating states and undefined operation.

Key Specifications

Pinout & Package

CD74HC4538QM96Q1 is packaged in a 16-pin SOIC (D package), 9.9 mm × 6.0 mm body size, with standard 1.27 mm pitch and gull-wing leads. The package is RoHS-compliant, moisture sensitivity level 1, and rated for reflow up to 260°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G123DBVR and CD74HC221M96, the CD74HC4538QM96Q1 uniquely combines dual retriggerable operation, automotive qualification, Schmitt-trigger inputs, and full 2–6 V supply flexibility - making it the only option for safety-critical, multi-event timing in harsh environments.

Availability

CD74HC4538QM96Q1 is available at Aetrix Electronics and suitable for automotive power management, industrial sensor interface, and medical instrument timing requiring stable component supply across extended temperature and long product lifecycles.

Supply support for CD74HC4538QM96Q1 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 focused on analog and embedded processing technologies, with decades of automotive-grade IC development and AEC-Q100 validation expertise.

The CD74HC4538QM96Q1 belongs to TI's automotive HC logic family, designed specifically for high-reliability timing functions in engine control, body electronics, and ADAS subsystems where precision, noise immunity, and temperature resilience are mandatory.

FAQ

What is the minimum external resistor value supported by CD74HC4538QM96Q1?

The CD74HC4538QM96Q1 specifies a minimum external timing resistor (RX) of 5 kΩ per channel, as defined in the Recommended Operating Conditions table. Using lower values may cause excessive current draw, timing inaccuracies, or device instability due to internal node loading. This limit ensures reliable operation across the full –40°C to +125°C temperature range and maintains specified pulse-width accuracy for the CD74HC4538QM96Q1.

Does CD74HC4538QM96Q1 support both rising- and falling-edge triggering on the same channel?

Yes, the CD74HC4538QM96Q1 supports independent rising-edge triggering on pin 4A (Ch1) and pin 12A (Ch2), and falling-edge triggering on pin 5B (Ch1) and pin 11B (Ch2). Each channel can be configured for either edge type - but not both simultaneously on the same input pin. Unused A inputs must be tied to GND and unused B inputs to VCC to prevent floating and undefined behavior in the CD74HC4538QM96Q1.

How does the retriggerable mode function in CD74HC4538QM96Q1?

In retriggerable mode, the CD74HC4538QM96Q1 extends the current output pulse by one full timing period (τ) upon each new valid trigger input - whether from A or B. This allows continuous pulse stretching during ongoing events, such as monitoring a signal that remains active beyond the initial timeout. The retrigger time is independent of CX, ensuring predictable behavior regardless of selected pulse width in the CD74HC4538QM96Q1.

Is CD74HC4538QM96Q1 pin-compatible with the commercial-grade CD74HC4538?

Yes, the CD74HC4538QM96Q1 shares identical pinout, electrical characteristics, and functional behavior with the commercial CD74HC4538, including SOIC-16 footprint and terminal assignments. The primary differences are automotive qualification (AEC-Q100 Grade 1), extended temperature range (–40°C to +125°C vs. –40°C to +85°C), and enhanced reliability testing - all implemented without altering the CD74HC4538QM96Q1 pin configuration or logic functionality.

What is the maximum recommended external capacitor value for CD74HC4538QM96Q1?

The CD74HC4538QM96Q1 datasheet does not specify a maximum external timing capacitor (CX) value, but practical limits arise from leakage current, board parasitics, and timing accuracy degradation. For stable operation across –40°C to +125°C, TI recommends keeping CX ≤ 1 µF when using standard ceramic or film capacitors. Larger values increase sensitivity to temperature drift and dielectric absorption, potentially affecting pulse-width repeatability in the CD74HC4538QM96Q1.