CD14538BE-NG Equivalent & Substitute Parts

Part Overview

The CD14538BE-NG is a monostable multivibrator logic integrated circuit manufactured by Texas Instruments, belonging to the 4000B series. This device features two independent circuits with Schmitt trigger inputs and a propagation delay of 100 ns, housed in a 16-pin DIP package for through-hole mounting. The CD14538BE-NG is classified as obsolete, making identification of functionally equivalent substitute components necessary for ongoing design support, maintenance, and new production applications where through-hole or surface-mount alternatives are acceptable.

Substiute Parts

CD14538BE-NG

Texas InstrumentsIn Stock: 771CD14538BE-NG Datasheet

Current PartRFQ

CD74HC123PWR

Texas InstrumentsIn Stock: 50164CD74HC123PWR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the CD14538BE-NG is determined by the following critical parameters:

Functional Equivalence Criteria:

• Logic type: Monostable multivibrator
• Independent circuits: 2
• Operating temperature range: -55°C ~ 125°C (must match or exceed)
• RoHS compliance: ROHS3 Compliant

Acceptable Parameter Variations:

• Propagation delay: Faster speeds (lower ns values) are acceptable in most applications
• Schmitt trigger input: Not required for substitution
• Output current: Variations within typical logic levels are acceptable
• Supply voltage range: Narrower ranges are acceptable if application voltage falls within specified range
• Mounting type: Both through-hole and surface-mount packages qualify as substitutes
• Package form factor: Different package types acceptable based on circuit board design requirements

The CD74HC123PWR qualifies as a direct functional substitute based on matching logic type, circuit count, temperature range, and compliance certifications, despite differences in propagation delay, mounting technology, and supply voltage specifications.

Parameter Comparison

Engineering Selection Recommendations

Product Status Consideration: The CD14538BE-NG is classified as obsolete. The CD74HC123PWR is an active product with high inventory availability (50,084 pcs), ensuring long-term supply chain reliability and continued manufacturer support.

Compliance and Certification: Both components are ROHS3 compliant, meeting environmental and regulatory requirements for current manufacturing standards. The CD74HC123PWR includes additional compliance documentation (REACH Unaffected, ECCN: EAR99, HTSUS: 8542.39.0001).

Functional Compatibility: Both devices perform identical monostable multivibrator functions with two independent circuits and matching operating temperature ranges. The CD74HC123PWR offers improved propagation delay performance (25 ns versus 100 ns), which is advantageous for timing-critical applications.

Supply Voltage Consideration: The CD14538BE-NG operates across 3 V ~ 18 V. The CD74HC123PWR operates across 2 V ~ 6 V. Applications requiring supply voltages above 6 V cannot use the CD74HC123PWR as a direct substitute without additional voltage regulation circuitry.

Packaging and Board Design: Selection between through-hole (CD14538BE-NG) and surface-mount (CD74HC123PWR) depends on circuit board design and manufacturing capabilities. Surface-mount technology offers space efficiency; through-hole mounting provides mechanical robustness for high-vibration environments.

Frequently Asked Questions (FAQ)

Q: Can the CD74HC123PWR directly replace the CD14538BE-NG in all applications?

A: Functional replacement is possible when the application supply voltage operates within 2 V ~ 6 V. Applications requiring supply voltages above 6 V require alternative solutions or voltage regulation. Packaging differences (surface-mount versus through-hole) require circuit board design modifications.

Q: What is the significance of the propagation delay difference (100 ns versus 25 ns)?

A: The CD74HC123PWR has faster propagation delay, meaning output transitions occur more quickly. For most timing applications, faster propagation is beneficial. Applications with timing constraints dependent on the original 100 ns delay require circuit analysis to confirm compatibility.

Q: Are there pin-to-pin compatibility considerations?

A: Both devices contain two independent monostable circuits in 16-pin packages. Pin assignments must be verified against specific application schematics, as package type differences (DIP versus TSSOP) may affect physical layout but not functional pin mapping.

Q: What is the Schmitt trigger input difference?

A: The CD14538BE-NG includes Schmitt trigger inputs; the CD74HC123PWR does not. Schmitt trigger inputs provide hysteresis for noise immunity on input signals. Applications requiring this feature must evaluate alternative substitutes or add external hysteresis circuitry.

Q: How does the output current difference affect circuit design?

A: The CD14538BE-NG provides 6.8 mA output current; the CD74HC123PWR provides 5.2 mA. Both values are within standard logic output specifications. Load impedance calculations should confirm that 5.2 mA is sufficient for connected logic inputs and any external loads.

Q: Is the CD74HC123PWR suitable for new designs?

A: Yes. The CD74HC123PWR is an active product with full manufacturer support, comprehensive documentation, and high availability. It is the recommended choice for new designs requiring monostable multivibrator functionality with two independent circuits.