LM7809ACT Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The LM7809ACT 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 LM7809ACT serves applications requiring regulated 9V power from higher input voltages up to 35V, with integrated over-temperature and short-circuit protection. As an obsolete product, identifying compatible alternatives ensures design continuity and supply chain reliability.

Substiute Parts

LM7809ACT

onsemiIn Stock: 1333LM7809ACT Datasheet

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MC78M09CTG

onsemiIn Stock: 2766MC78M09CTG Datasheet

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MC7809ACTG

onsemiIn Stock: 1766MC7809ACTG Datasheet

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MC7809CTG

onsemiIn Stock: 23360MC7809CTG Datasheet

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L7809CV

STMicroelectronicsIn Stock: 204263L7809CV Datasheet

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L7809ABV-DG

STMicroelectronicsIn Stock: 963L7809ABV-DG Datasheet

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L7809CV-DG

STMicroelectronicsIn Stock: 53331L7809CV-DG Datasheet

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L78M09CV

STMicroelectronicsIn Stock: 9997L78M09CV Datasheet

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L78S09CV

STMicroelectronicsIn Stock: 2712L78S09CV Datasheet

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MC7809BTG

onsemiIn Stock: 7768MC7809BTG Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution compatibility for the LM7809ACT is determined by the following critical parameters:

• Output Voltage: Must be fixed at 9V
• Output Current Capacity: Minimum 1A (equal or greater capacity acceptable)
• Input Voltage Range: Maximum 35V or higher
• Package / Case: TO-220-3 form factor for mechanical and thermal compatibility
• Mounting Type: Through-hole configuration
• Protection Features: Over-temperature and short-circuit protection required

Substitute parts are grouped into three categories:

Parametric Equivalents (MC7809ACTG, MC7809CTG): Identical electrical specifications and current rating to the LM7809ACT, differing only in manufacturer or product status.

Direct Equivalents (L7809CV, L7809CV-DG): Higher current capacity (1.5A) with identical voltage output and package, providing enhanced performance margin.

Similar Alternatives (MC78M09CTG, L78M09CV): Reduced current capacity (500mA) suitable only for applications with lower current requirements. L78S09CV provides 2A capacity for higher-demand applications.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: MC7809CTG

MC7809CTG is the preferred substitute for the LM7809ACT. It maintains identical electrical specifications (1A output current, 2V dropout voltage, 8 mA quiescent current) and is currently in active product status, ensuring long-term availability and supply chain stability. Both devices are ROHS3 compliant and share the TO-220-3 package. The MC7809CTG is manufactured by onsemi, the same supplier as the original part.

Secondary Recommendation: L7809CV or L7809CV-DG

For applications requiring enhanced current capacity margin, L7809CV and L7809CV-DG provide 1.5A output current while maintaining the same 9V output voltage and TO-220-3 package. These STMicroelectronics devices are ROHS3 compliant and suitable for designs where additional headroom is beneficial. Both are obsolete but maintain substantial inventory availability.

Extended Temperature Range Option: L7809ABV-DG or MC7809BTG

Applications requiring operation below 0°C should use L7809ABV-DG (STMicroelectronics, -40°C to 125°C) or MC7809BTG (onsemi, -40°C to 125°C). Both maintain 1A or 1.5A output capacity and are ROHS3 compliant.

Current-Limited Applications: MC78M09CTG or L78M09CV

For designs with maximum 500mA current requirements, MC78M09CTG (onsemi) or L78M09CV (STMicroelectronics) provide reduced current rating. These are suitable only when application current demand does not exceed 500mA.

High-Current Applications: L78S09CV

Applications requiring 2A output current should use L78S09CV (STMicroelectronics). This device extends the operating temperature range to 150°C and provides the highest current capacity among available substitutes.

Frequently Asked Questions (FAQ)

Q: Can MC7809CTG directly replace LM7809ACT without circuit modifications?

A: Yes. MC7809CTG is a parametric equivalent with identical output voltage (9V), output current (1A), input voltage rating (35V max), and TO-220-3 package. No circuit modifications are required. The primary advantage is active product status, ensuring continued availability.

Q: What is the difference between L7809CV and L7809CV-DG?

A: Both are STMicroelectronics devices with identical electrical specifications (1.5A output, 9V fixed output, 35V max input). The "-DG" suffix indicates a specific packaging or distribution variant. Both are functionally equivalent for circuit design purposes.

Q: Can I use L78S09CV (2A) in place of LM7809ACT (1A)?

A: Yes, L78S09CV is a direct substitute with higher current capacity. The 2A rating provides additional margin for applications originally designed for 1A. The TO-220-3 package and 9V output voltage are identical. However, the PSRR is lower (47dB vs. 71dB), which may affect noise-sensitive applications.

Q: Are all substitute parts ROHS3 compliant?

A: All listed substitute parts are ROHS3 compliant except the original LM7809ACT, which does not specify RoHS status. This ensures compliance with current environmental regulations.

Q: What is the significance of the operating temperature range difference?

A: The LM7809ACT operates from 0°C to 125°C. Substitutes like L7809ABV-DG and MC7809BTG extend the lower limit to -40°C, enabling use in industrial and automotive applications requiring wider temperature operation. Standard-range parts (0°C to 125°C) are suitable for commercial and consumer applications.

Q: Can I use MC78M09CTG (500mA) if my circuit draws 1A?

A: No. MC78M09CTG is rated for maximum 500mA output current. Using it in a 1A application will cause the device to enter current-limiting protection or thermal shutdown. Use only if your actual circuit current requirement does not exceed 500mA.

Q: What does PSRR (71dB vs. 61dB) mean for my application?

A: PSRR (Power Supply Rejection Ratio) measures how well the regulator rejects input voltage noise. Higher PSRR (71dB in LM7809ACT) provides better noise rejection. Substitutes with lower PSRR (61dB in MC7809CTG) are still suitable for most applications but may require additional filtering in noise-sensitive circuits such as audio or precision measurement systems.

Q: Is the TO-220-3 package identical across all substitutes?

A: Yes. All listed substitutes use the TO-220-3 through-hole package with identical pin configuration and thermal characteristics. Direct PCB and heatsink compatibility is maintained across all parts.