MC78FC30HT1G Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The MC78FC30HT1G is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed 3V positive output at 50mA. This Surface Mount device in SOT-89-3 packaging is classified as obsolete, making identification of suitable substitute components essential for ongoing design support and production continuity. The part operates across an input voltage range up to 10V with a maximum dropout voltage of 0.7V at 40mA, incorporating over-current protection features.

Substiute Parts

MC78FC30HT1G

onsemiIn Stock: 4315MC78FC30HT1G Datasheet

Current PartRFQ

S-817B30AUA-CWTT2U

ABLIC Inc.In Stock: 1542S-817B30AUA-CWTT2U Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MC78FC30HT1G is determined by strict equivalence across the following critical parameters:

• Fixed output voltage of 3V
• Maximum output current of 50mA
• Maximum input voltage of 10V
• Surface Mount packaging in SOT-89-3 (TO-243AA)
• Positive output configuration
• Single regulator output

The S-817B30AUA-CWTT2U from ABLIC Inc. meets all these core electrical and mechanical requirements, making it a direct functional equivalent. Both devices share identical output specifications, input voltage ratings, and physical packaging, enabling pin-compatible substitution in circuit designs.

Parameter Comparison

Engineering Selection Recommendations

The S-817B30AUA-CWTT2U is the qualified substitute for the obsolete MC78FC30HT1G. Selection rationale is based on the following factors:

• Both devices are electrically and mechanically equivalent across all critical parameters
• The substitute maintains identical output voltage (3V) and current rating (50mA)
• Pin-compatible SOT-89-3 packaging enables direct board-level replacement
• The substitute device is in Active product status, ensuring long-term availability and supply chain continuity
• The S-817B30AUA-CWTT2U demonstrates superior performance characteristics: lower dropout voltage (0.41V vs 0.7V) and reduced quiescent current (2.5 µA vs 3.3 µA)
• The substitute operates across a wider temperature range (-40°C ~ 85°C vs -30°C ~ 80°C), providing enhanced thermal margin
• RoHS3 compliance of the substitute aligns with modern manufacturing standards
• Both devices carry identical REACH and ECCN classifications, maintaining regulatory consistency

Frequently Asked Questions (FAQ)

Q: Can the S-817B30AUA-CWTT2U directly replace the MC78FC30HT1G on existing PCBs?

A: Yes. Both devices use identical SOT-89-3 packaging with the same pin configuration, enabling direct pin-compatible substitution without PCB modifications.

Q: What are the key differences between these two regulators?

A: The primary differences are product status (obsolete vs. active) and performance characteristics. The S-817B30AUA-CWTT2U offers lower dropout voltage (0.41V vs. 0.7V at specified test conditions) and lower quiescent current (2.5 µA vs. 3.3 µA). The substitute also operates across a wider temperature range (-40°C to 85°C vs. -30°C to 80°C).

Q: Are there any circuit design considerations when switching to the substitute part?

A: No circuit redesign is required. Both regulators maintain identical electrical specifications for output voltage, output current, and input voltage ratings. The improved dropout voltage and quiescent current of the substitute may provide marginal benefits in power efficiency and thermal performance.

Q: What is the packaging format difference between the main part and substitute?

A: There is no packaging difference. Both the MC78FC30HT1G and S-817B30AUA-CWTT2U use TO-243AA (SOT-89-3) Surface Mount packaging. The substitute is supplied in Cut Tape (CT) format, which is standard for production environments.

Q: Does the substitute part have the same protection features?

A: The MC78FC30HT1G specifies over-current protection. The S-817B30AUA-CWTT2U does not list protection features in the provided specifications. Verify detailed datasheets if over-current protection is a critical design requirement.

Q: What is the inventory status for these parts?

A: The MC78FC30HT1G has 4,300 pieces in stock (obsolete status). The S-817B30AUA-CWTT2U has 1,487 pieces in stock and is an active product with ongoing manufacturing support.