KA278R09CTU Equivalent & Substitute Parts

Part Overview

The KA278R09CTU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 9V output at 2A current capacity in a TO-220-4 package configuration. This component is classified as a Power Management (PMIC) device and is currently listed as obsolete. Due to its obsolete status and potential supply constraints, identifying functionally equivalent substitute parts is essential for design continuity and procurement planning.

Substiute Parts

KA278R09CTU

onsemiIn Stock: 1421KA278R09CTU Datasheet

Current PartRFQ

L78S09CV

STMicroelectronicsIn Stock: 2712L78S09CV Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the KA278R09CTU are identified based on the following critical electrical and mechanical parameters:

• Fixed output voltage of 9V
• Output current capacity of 2A
• Maximum input voltage of 35V
• Through-hole mounting configuration
• Linear regulator topology with positive output configuration
• Protection features including over-current and over-temperature protection

The L78S09CV from STMicroelectronics meets these core substitution criteria. Both devices share identical output voltage and current specifications, matching input voltage ratings, and compatible through-hole mounting. Functional equivalence is established through these aligned electrical parameters.

Parameter Comparison

Engineering Selection Recommendations

The L78S09CV serves as a direct functional equivalent for the KA278R09CTU based on matching electrical specifications for output voltage, output current, and input voltage ratings. Both devices are classified as obsolete, indicating similar market lifecycle status.

The L78S09CV offers RoHS3 compliance, which may be advantageous for applications subject to environmental or regulatory requirements. The substitute part demonstrates lower quiescent current (8 mA versus 10 mA) and provides specified PSRR performance (47dB at 120Hz), which may benefit noise-sensitive applications.

Package configuration differs between the two devices: the KA278R09CTU uses a TO-220-4 package while the L78S09CV uses a TO-220-3 package. This difference requires verification of PCB layout compatibility and pin assignment alignment before implementation.

The L78S09CV supports an extended operating temperature range (0°C ~ 150°C) compared to the KA278R09CTU (-20°C ~ 80°C). Applications requiring operation below 0°C must retain the original part or identify alternatives with appropriate temperature specifications.

Frequently Asked Questions (FAQ)

Q: Can the L78S09CV directly replace the KA278R09CTU without circuit modifications?

A: The L78S09CV matches the critical electrical parameters (9V output, 2A current, 35V maximum input). However, the package configuration differs (TO-220-3 versus TO-220-4), requiring PCB layout verification and pin assignment confirmation before implementation.

Q: What is the significance of the package difference between TO-220-4 and TO-220-3?

A: The TO-220-4 package includes four pins while the TO-220-3 package includes three pins. Pin assignments and functionality must be verified against the specific circuit design. Physical footprint compatibility on the PCB must be confirmed.

Q: Are both parts suitable for new designs?

A: Both the KA278R09CTU and L78S09CV are classified as obsolete. For new designs, evaluation of current-generation linear regulators with similar specifications is recommended to ensure long-term supply availability.

Q: What are the implications of the different operating temperature ranges?

A: The KA278R09CTU operates from -20°C to 80°C, while the L78S09CV operates from 0°C to 150°C. Applications requiring operation below 0°C must use the original part or identify alternatives with matching low-temperature specifications.

Q: How do the quiescent current differences affect circuit performance?

A: The L78S09CV draws 8 mA quiescent current compared to 10 mA for the KA278R09CTU. This 2 mA difference is negligible in most applications but may provide minor power consumption benefits in battery-powered or low-power systems.

Q: What compliance advantages does the L78S09CV offer?

A: The L78S09CV is RoHS3 compliant, which may be required for applications subject to environmental regulations or customer specifications. The KA278R09CTU compliance status is not specified in available documentation.