KA7809ETU Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The KA7809ETU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 9V output at 1A current capacity in a TO-220-3 through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and component procurement. The KA7809ETU serves applications requiring stable 9V regulation from input sources up to 35V with integrated over-temperature and short-circuit protection.

Substiute Parts

KA7809ETU

onsemiIn Stock: 23130KA7809ETU Datasheet

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MC7809ACTG

onsemiIn Stock: 1766MC7809ACTG Datasheet

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MC7809CTG

onsemiIn Stock: 23360MC7809CTG Datasheet

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MC78M09CTG

onsemiIn Stock: 2766MC78M09CTG Datasheet

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MC7809BTG

onsemiIn Stock: 7768MC7809BTG Datasheet

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L7809ABV-DG

STMicroelectronicsIn Stock: 963L7809ABV-DG Datasheet

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L7809CV

STMicroelectronicsIn Stock: 204263L7809CV Datasheet

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L78M09CV

STMicroelectronicsIn Stock: 9997L78M09CV Datasheet

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L78S09CV

STMicroelectronicsIn Stock: 2712L78S09CV Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the KA7809ETU is determined by the following critical parameters:

Primary Substitution Criteria:

• Fixed output voltage of 9V
• Output current capability (minimum 1A for direct substitution)
• Input voltage rating (maximum 35V or higher)
• TO-220-3 package / through-hole mounting
• Operating temperature range compatibility

Substitution Categories:

Category 1: Direct Equivalents (1A Output Current) Parts MC7809CTG, MC7809BTG, and MC7809ACTG from onsemi maintain identical 1A output current specifications. MC7809CTG is currently active in production, while MC7809BTG and MC7809ACTG are obsolete. These parts are pin-compatible and functionally equivalent for applications requiring exactly 1A output.

Category 2: Higher Current Capability (1.5A Output Current) Parts L7809ABV-DG and L7809CV from STMicroelectronics provide 1.5A output current, exceeding the KA7809ETU specification. These are suitable for applications where additional current margin is beneficial and are backward-compatible in terms of voltage regulation and package form factor.

Category 3: Reduced Current Capability (500mA Output Current) Parts MC78M09CTG and L78M09CV provide 500mA output current. These are suitable only for applications with reduced current requirements and should not be used as direct replacements in designs requiring full 1A capacity.

Category 4: Enhanced Current Capability (2A Output Current) Part L78S09CV provides 2A output current with extended operating temperature range to 150°C. This part offers maximum design margin and is suitable for applications requiring higher current or enhanced thermal performance.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: MC7809CTG MC7809CTG is the preferred substitute for new designs and ongoing production. This part maintains identical electrical specifications to the KA7809ETU (1A output, 9V fixed, 35V maximum input) while offering active product status and ROHS3 compliance. The operating temperature range is 0°C to 125°C, which is suitable for most commercial and industrial applications. The slightly lower PSRR (61dB versus 71dB) is acceptable for standard voltage regulation applications.

Secondary Recommendation: L7809ABV-DG or L7809CV For applications requiring additional current margin or enhanced thermal performance, STMicroelectronics L7809ABV-DG or L7809CV provide 1.5A output current in the same TO-220-3 package. Both parts maintain the 9V output and 35V maximum input specifications. L7809ABV-DG supports the extended temperature range (-40°C to 125°C) matching the KA7809ETU, while L7809CV operates from 0°C to 125°C.

Alternative for Extended Temperature: MC7809BTG MC7809BTG maintains the full -40°C to 125°C operating range of the KA7809ETU with identical 1A output specifications. This part is suitable for applications requiring extended low-temperature operation.

Not Recommended for Direct Substitution: MC78M09CTG, L78M09CV, L78S09CV These parts provide reduced (500mA) or increased (2A) output current and should only be selected when application requirements specifically call for these current levels. They are not suitable as direct replacements for 1A-rated designs.

Frequently Asked Questions (FAQ)

Q: Can MC7809CTG directly replace KA7809ETU in existing designs? A: Yes. MC7809CTG is electrically and mechanically compatible with KA7809ETU. Both provide 9V fixed output at 1A in TO-220-3 packages. The primary difference is operating temperature range (0°C to 125°C for MC7809CTG versus -40°C to 125°C for KA7809ETU). Verify your application's minimum operating temperature requirement before substitution.

Q: What is the difference between 1A, 1.5A, and 2A output current variants? A: Output current rating indicates the maximum continuous current the regulator can supply. The KA7809ETU is rated for 1A. Parts rated for 1.5A (L7809ABV-DG, L7809CV) or 2A (L78S09CV) can supply higher current but are backward-compatible with 1A applications. Parts rated for 500mA (MC78M09CTG, L78M09CV) cannot supply full 1A and are unsuitable for direct replacement.

Q: Are all substitute parts ROHS3 compliant? A: All listed substitute parts carry ROHS3 compliance certification. The original KA7809ETU does not specify RoHS status. If RoHS compliance is required for your application, select from the substitute parts list.

Q: Does package form factor differ between these parts? A: All listed parts use TO-220-3 through-hole packages with identical pin configurations and mechanical dimensions. They are physically interchangeable on PCBs designed for TO-220-3 components.

Q: What is PSRR and why does it vary between parts? A: PSRR (Power Supply Rejection Ratio) measures the regulator's ability to reject input voltage ripple. Higher PSRR values indicate better noise rejection. The KA7809ETU specifies 71dB at 120Hz. Substitute parts range from 47dB to 80dB. For applications sensitive to input noise, select parts with higher PSRR values (MC78M09CTG at 80dB or L7809ABV-DG at 61dB).

Q: Can I use L78S09CV (2A) instead of KA7809ETU (1A)? A: Yes, L78S09CV is backward-compatible and provides additional current capacity. However, it operates only to 0°C minimum temperature (versus -40°C for KA7809ETU) and has lower PSRR (47dB). Use this part only if your application does not require extended low-temperature operation or high noise rejection.

Q: What protection features are included in these regulators? A: All parts include over-temperature and short-circuit protection. L78M09CV and L78S09CV additionally include over-current protection. These protections are standard across the 9V linear regulator family and do not differentiate substitution suitability.