MC78T15ACT Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The MC78T15ACT is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 15V output at 3A maximum current in a TO-220-3 package. This device is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The MC78T15ACT delivers regulated 15V output from input voltages up to 40V with integrated over-current and over-temperature protection.

Substiute Parts

MC78T15ACT

onsemiIn Stock: 930MC78T15ACT Datasheet

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AS7815AT-E1

Diodes IncorporatedIn Stock: 18573AS7815AT-E1 Datasheet

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L7815CV-DG

STMicroelectronicsIn Stock: 176051L7815CV-DG Datasheet

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LM7815CT/NOPB

Texas InstrumentsIn Stock: 3504LM7815CT/NOPB Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MC78T15ACT are selected based on the following critical parameters that determine functional compatibility:

• Fixed Output Voltage: All substitutes must provide 15V fixed output
• Package / Case: All substitutes must use TO-220-3 package for mechanical and thermal compatibility
• Mounting Type: Through-hole mounting required
• Output Configuration: Positive fixed output configuration
• Number of Regulators: Single regulator per device

The three substitute parts listed below meet these core requirements. However, they differ in maximum output current capability and input voltage ratings, which affects their suitability for specific applications.

Parameter Comparison

Engineering Selection Recommendations

For applications requiring 3A output current: The MC78T15ACT is the only part in this group rated for 3A continuous output. No direct substitute with equivalent 3A capability is available from the provided list. Applications requiring 3A output cannot be directly substituted with the listed alternatives without circuit redesign or parallel configuration considerations.

For applications requiring ≤1.5A output current: The L7815CV-DG from STMicroelectronics is the preferred substitute, offering 1.5A maximum output current, which provides the highest current capability among the lower-rated alternatives while maintaining 15V fixed output and TO-220-3 package compatibility.

For applications requiring ≤1A output current: Both AS7815AT-E1 (Diodes Incorporated) and LM7815CT/NOPB (Texas Instruments) are suitable. The LM7815CT/NOPB offers superior PSRR performance (70dB versus 58dB) and extended protection features including over-current protection. The AS7815AT-E1 provides extended operating temperature range (-40°C to 125°C).

RoHS compliance: All three substitute parts are ROHS3 compliant, whereas the MC78T15ACT is RoHS non-compliant. New designs should prioritize compliant alternatives.

Product availability: All substitute parts carry active product status with substantial inventory availability, ensuring long-term supply continuity.

Frequently Asked Questions (FAQ)

Q: Can the AS7815AT-E1 directly replace the MC78T15ACT in all applications?

A: The AS7815AT-E1 is mechanically and electrically compatible in terms of package, pinout, and output voltage. However, it is rated for 1A maximum output current compared to the MC78T15ACT's 3A rating. Direct substitution is only suitable for applications drawing ≤1A from the 15V output.

Q: What is the primary limitation when substituting these parts?

A: The maximum output current rating is the primary differentiator. The MC78T15ACT delivers 3A, while all listed substitutes are rated for 1A to 1.5A. Applications requiring the full 3A capability cannot use these substitutes without circuit modification.

Q: Are all substitute parts pin-compatible with the MC78T15ACT?

A: Yes. All substitute parts use the TO-220-3 package with identical pinout: input, ground, and output. No PCB layout changes are required for mechanical compatibility.

Q: Which substitute offers the best noise performance?

A: The LM7815CT/NOPB provides the highest PSRR at 70dB (120Hz), making it the best choice for noise-sensitive applications requiring low-noise 15V regulation.

Q: Can I use the L7815CV-DG in a high-temperature environment?

A: The L7815CV-DG operates from 0°C to 125°C. For applications requiring operation below 0°C, the AS7815AT-E1 supports -40°C to 125°C and is the appropriate choice.

Q: What are the compliance differences between the MC78T15ACT and its substitutes?

A: The MC78T15ACT is RoHS non-compliant. All three substitutes (AS7815AT-E1, L7815CV-DG, and LM7815CT/NOPB) are ROHS3 compliant, meeting current environmental and regulatory requirements for new product designs.

Q: Is the input voltage rating difference significant?

A: Yes. The MC78T15ACT accepts input up to 40V, while substitutes are rated for 32V to 35V. Applications with input voltages exceeding 35V cannot use the listed substitutes and require alternative solutions.