Renesas 74HC4538FP-E

Overview

74HC4538FP-E from Renesas Electronics is a dual precision retriggerable/resettable monostable multivibrator in SOP-16 package, operating from 2 V to 6 V supply, delivering pulse widths from 14 ns to >70 µs via external R/C timing networks, and featuring 22 ns typical propagation delay (A/B to Q) at VCC = 4.5 V with CL = 50 pF - used for precise timing control in digital logic interfaces, debounce circuits, and pulse shaping in industrial control systems.

For engineers reviewing the 74HC4538FP-E datasheet, 74HC4538FP-E pinout, 74HC4538FP-E application, or 74HC4538FP-E equivalent, key selection considerations include retriggerable operation mode, independent clear inputs per channel, wide VCC range compatibility, temperature-stable pulse width generation, and SOP-16 footprint suitability for space-constrained PCB layouts.

Technical Context

The 74HC4538FP-E integrates two independent monostable multivibrators, each with separate negative-edge (B) and positive-edge (A) trigger inputs plus an active-low clear (CD) input. Its internal architecture uses precision voltage references (~1/3 VCC and ~2/3 VCC) to control capacitor discharge/charge cycles across external RX/CX components.

Each channel supports both retriggerable and non-retriggerable modes via external configuration. Pulse width is determined solely by external RC values using tw ≈ 0.7 × R × C, with <±0.1% matching between channels at VCC = 5.0 V, RX = 10 kΩ, CX = 1000 pF - enabling synchronized timing in dual-channel applications like encoder signal conditioning or dual-edge detection.

Key Specifications

Pinout & Package

SOP-16 (JEITA standard, FP-16DAV footprint, 1.27 mm pitch), 10.06 mm × 5.5 mm body, 1.75 mm max height, Ni/Pd/Au-plated leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV4538ADR and MC74HC4538DG, the 74HC4538FP-E offers broader supply voltage flexibility (2–6 V), tighter pulse-width matching (±0.1%), and JEITA-compliant SOP-16 packaging optimized for automated assembly - making it preferred for multi-rail industrial controllers and legacy-compatible designs.

Availability

74HC4538FP-E is available at Aetrix Electronics and suitable for industrial control panels, encoder interface modules, and serial communication line conditioners requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HC4538FP-E 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

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and timing solutions for industrial, automotive, and infrastructure markets.

The HD74HC4538 product line delivers precision timing ICs designed specifically for deterministic pulse generation, debouncing, and signal conditioning in noise-prone industrial environments - emphasizing reliability, wide-VCC operation, and consistent parametric performance.

FAQ

What is the maximum operating frequency of the 74HC4538FP-E?

The 74HC4538FP-E does not operate at a fixed clock frequency; it is a monostable multivibrator whose output pulse width is externally set by R and C components. Minimum pulse width is 14 ns at VCC = 6.0 V, allowing effective use in systems with repetition rates up to ~70 MHz under ideal conditions. The 74HC4538FP-E's 22 ns typical propagation delay ensures minimal latency between trigger and output assertion.

Can the 74HC4538FP-E be used in non-retriggerable mode?

Yes, the 74HC4538FP-E supports non-retriggerable operation through external wiring - specifically by connecting the Q output to the CD (clear) input of the same channel. This configuration forces termination of the current pulse upon completion, preventing extension by subsequent triggers. The 74HC4538FP-E datasheet provides Figure 4 showing exact circuit implementation for non-retriggerable mode.

What are the recommended external R and C values for a 10 µs pulse width with the 74HC4538FP-E?

Using the formula tw ≈ 0.7 × R × C, a 10 µs pulse requires R × C ≈ 14.3 kΩ·µF. For stability and noise immunity, select R = 100 kΩ and C = 143 pF (standard E24 value). At VCC = 5.0 V, this yields tw ≈ 10.0 µs with <±1% error. The 74HC4538FP-E's internal reference accuracy ensures consistent results across temperature without trimming.

Does the 74HC4538FP-E require pull-up or pull-down resistors on unused trigger inputs?

Yes - unused trigger inputs (A or B) on the 74HC4538FP-E must be terminated to a valid logic level: tie A to VCC for disable, or B to GND for disable. Leaving them floating risks spurious triggering due to noise coupling. The 74HC4538FP-E's high-impedance CMOS inputs make proper termination essential for robust operation in electrically noisy industrial settings.

Is the 74HC4538FP-E RoHS compliant and halogen-free?

Yes, the 74HC4538FP-E meets EU RoHS Directive 2011/65/EU requirements and is manufactured as a halogen-free device. Renesas Electronics confirms compliance in its official environmental documentation, and the 74HC4538FP-E carries appropriate marking per JEDEC standards. No exemptions apply - full material declarations are available upon request from Aetrix Electronics.