MC7818ACTG Equivalent & Substitute Parts

Part Overview

The MC7818ACTG is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 18V output at 1A current capacity in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The MC7818ACTG features integrated over-temperature and short-circuit protection, making it suitable for applications requiring regulated 18V power distribution with thermal safeguards.

Substiute Parts

MC7818ACTG

onsemiIn Stock: 1773MC7818ACTG Datasheet

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MC7818CTG

onsemiIn Stock: 1503MC7818CTG Datasheet

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L78S18CV

STMicroelectronicsIn Stock: 2795L78S18CV Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MC7818ACTG are determined by the following critical parameters:

• Output Voltage: Must be fixed at 18V
• Package / Case: Must be TO-220-3 for mechanical and thermal compatibility
• Mounting Type: Must be Through Hole
• Output Configuration: Must be Positive
• Number of Regulators: Must be 1
• RoHS Compliance: Must maintain ROHS3 Compliant status

The MC7818ACTG has two identified substitutes: MC7818CTG (onsemi) and L78S18CV (STMicroelectronics). Both maintain the same 18V fixed output voltage and TO-220-3 package configuration. Differences in output current capacity, quiescent current, and product status are noted but do not prevent substitution when electrical requirements are met.

Parameter Comparison

Engineering Selection Recommendations

MC7818CTG (onsemi): This substitute is the preferred choice for direct replacement. It maintains identical electrical specifications (1A output current, 18V fixed output, 2V dropout voltage, 57dB PSRR) and is currently in Active product status, ensuring long-term availability and supply chain stability. Both devices are manufactured by onsemi and share the same base product number (MC7818), confirming design compatibility.

L78S18CV (STMicroelectronics): This substitute provides higher output current capacity (2A versus 1A) and extended operating temperature range (0°C ~ 150°C versus 0°C ~ 125°C). It includes over-current protection in addition to over-temperature and short-circuit protection. However, the L78S18CV is classified as Obsolete, similar to the MC7818ACTG. The lower PSRR specification (43dB versus 57dB) may impact noise-sensitive applications. This substitute is suitable when higher current capacity is required and product obsolescence is acceptable.

Both substitutes maintain ROHS3 compliance and the TO-220-3 package configuration required for mechanical and thermal compatibility.

Frequently Asked Questions (FAQ)

Q: Can MC7818CTG be used as a direct replacement for MC7818ACTG?

A: Yes. The MC7818CTG is a direct substitute with identical electrical specifications. Both devices provide 18V fixed output at 1A, feature the same TO-220-3 package, and share the same base product number. The primary advantage of MC7818CTG is its Active product status, ensuring continued availability.

Q: What is the difference between MC7818ACTG and MC7818CTG?

A: The primary difference is product status. MC7818ACTG is Obsolete, while MC7818CTG is Active. Electrical specifications are identical: 1A output current, 18V fixed output, 2V dropout voltage, and 57dB PSRR at 120Hz. Both are manufactured by onsemi in TO-220-3 packages.

Q: Can L78S18CV replace MC7818ACTG in all applications?

A: L78S18CV is mechanically and electrically compatible for applications requiring 18V output. However, design considerations apply: L78S18CV provides 2A output current (versus 1A), operates to 150°C (versus 125°C), and includes over-current protection. The PSRR is lower at 43dB. Substitution is valid when these differences do not conflict with application requirements.

Q: Are all three parts RoHS compliant?

A: Yes. MC7818ACTG, MC7818CTG, and L78S18CV are all ROHS3 Compliant, meeting environmental and regulatory requirements for electronic component manufacturing and use.

Q: What is the significance of the TO-220-3 package for substitution?

A: The TO-220-3 package is a through-hole, three-terminal configuration (Input, Ground, Output) that defines mechanical fit, thermal characteristics, and PCB layout compatibility. All three substitutes maintain this package specification, ensuring pin-for-pin compatibility and identical mounting requirements.

Q: Why is quiescent current different between the three parts?

A: Quiescent current (Iq) varies due to internal circuit design differences between manufacturers and product generations. MC7818ACTG specifies 6 mA, MC7818CTG specifies 6.5 mA, and L78S18CV specifies 8 mA. These differences are minor and do not affect substitution validity for most applications.