CD74HC123EE4 Equivalent & Substitute Parts

Part Overview

The CD74HC123EE4 is a high-speed CMOS logic dual retriggerable monostable multivibrator manufactured by Texas Instruments. This device features two independent circuits with Schmitt trigger inputs, operating across a supply voltage range of 2 V to 6 V with a propagation delay of 26 ns. The component is packaged in a 16-PDIP through-hole configuration and is classified as obsolete. Due to its obsolete status and limited current inventory availability, identifying functionally equivalent active alternatives is essential for ongoing design support and production continuity.

Substiute Parts

CD74HC123EE4

Texas InstrumentsIn Stock: 928CD74HC123EE4 Datasheet

Current PartRFQ

CD74HC123PWR

Texas InstrumentsIn Stock: 50164CD74HC123PWR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the CD74HC123EE4 is determined by the following critical parameters:

Functional Equivalence Criteria:

• Logic type: Monostable multivibrator
• Independent circuits: 2
• Supply voltage range: 2 V ~ 6 V
• Operating temperature range: -55°C ~ 125°C
• Output current capability: 5.2 mA (high and low)
• Base product series: 74HC

Substitution Flexibility:

• Propagation delay tolerance: Substitute parts with equal or faster (lower) propagation delay are functionally compatible
• Schmitt trigger input: Not a mandatory matching criterion for functional substitution
• Mounting type and package: Determined by application requirements and PCB design constraints
• Product status: Active alternatives are preferred for long-term availability

The CD74HC123PWR qualifies as a direct functional substitute based on matching logic type, circuit count, supply voltage, operating temperature, and output current specifications. The faster propagation delay (25 ns versus 26 ns) and different package format represent design trade-offs rather than functional incompatibilities.

Parameter Comparison

Engineering Selection Recommendations

For Through-Hole Applications: The CD74HC123EE4 remains the specified component when PCB design mandates through-hole mounting. However, given its obsolete status and limited inventory (823 Pcs), long-term sourcing is not guaranteed. Designs should be evaluated for migration to surface-mount alternatives where feasible.

For New Designs or Redesigns: The CD74HC123PWR is the recommended substitute. It maintains functional equivalence across all critical parameters while offering the advantage of active product status, ensuring sustained availability. The surface-mount 16-TSSOP package is standard in modern electronics manufacturing. The faster propagation delay (25 ns) provides improved timing performance compared to the original specification.

Compliance and Certification: Both parts maintain ROHS3 compliance and REACH unaffected status, satisfying current regulatory requirements. The CD74HC123PWR's MSL rating of 1 (Unlimited) indicates superior moisture handling characteristics suitable for standard storage and handling conditions.

Frequently Asked Questions (FAQ)

Q: Can CD74HC123PWR directly replace CD74HC123EE4 in existing designs?

A: Functional replacement is possible when the application permits package and mounting type changes. The CD74HC123PWR provides equivalent logic functionality, identical supply voltage range, matching operating temperature range, and identical output current specifications. The faster propagation delay (25 ns) is a performance improvement. However, through-hole to surface-mount conversion requires PCB redesign.

Q: What is the significance of the propagation delay difference (26 ns vs. 25 ns)?

A: The CD74HC123PWR's 25 ns propagation delay is faster than the CD74HC123EE4's 26 ns specification. This represents a 1 ns improvement and is functionally compatible with designs specified for the original part. Timing-critical applications should verify that the faster delay does not introduce unintended circuit behavior.

Q: Does the absence of Schmitt trigger input on CD74HC123PWR affect substitution?

A: The CD74HC123EE4 includes Schmitt trigger input capability, while the CD74HC123PWR does not. This difference does not prevent functional substitution for standard monostable multivibrator applications. However, designs that specifically require Schmitt trigger hysteresis for noise immunity must retain the original part or identify alternative solutions.

Q: What are the packaging implications of switching from 16-DIP to 16-TSSOP?

A: The 16-DIP (0.300", 7.62 mm) is a through-hole package suitable for breadboarding and legacy PCB designs. The 16-TSSOP (0.173", 4.40 mm Width) is a surface-mount package requiring SMT assembly equipment and PCB redesign. The TSSOP package offers reduced board space and is standard in modern manufacturing. Existing through-hole designs cannot accommodate TSSOP packages without PCB modification.

Q: Why is CD74HC123EE4 classified as obsolete?

A: Obsolete status indicates that Texas Instruments has discontinued active production and support for this part number. Existing inventory may be available through authorized distributors, but long-term sourcing cannot be guaranteed. The CD74HC123PWR represents the active product line continuation for this functional category.

Q: Are there inventory considerations for component selection?

A: The CD74HC123EE4 has 823 Pcs in current stock, while the CD74HC123PWR has 50,084 Pcs available. The significantly higher inventory of the substitute part reflects its active status and ongoing market demand, supporting reliable long-term supply for production requirements.