KA7809ERTF Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The KA7809ERTF is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 9V output at 1A maximum current. This Surface Mount device in DPAK packaging is classified as Obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and production continuity. The part delivers regulated power management suitable for applications requiring stable 9V rails with moderate current demands.

Substiute Parts

KA7809ERTF

onsemiIn Stock: 885KA7809ERTF Datasheet

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MC78M09BDTRKG

onsemiIn Stock: 7216MC78M09BDTRKG Datasheet

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MC78M09CDTRKG

onsemiIn Stock: 10108MC78M09CDTRKG Datasheet

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BA17809FP-E2

Rohm SemiconductorIn Stock: 17905BA17809FP-E2 Datasheet

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L78M09CDT-TR

STMicroelectronicsIn Stock: 21292L78M09CDT-TR Datasheet

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MC78M09CDTG

onsemiIn Stock: 997MC78M09CDTG Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the KA7809ERTF is determined by the following critical parameters that must be maintained or exceeded:

Output Voltage: All substitute parts must provide a fixed 9V output to ensure direct functional replacement.

Output Current Capability: The KA7809ERTF delivers 1A maximum output current. Substitutes with 500mA output current are acceptable for applications where the full 1A capability is not required; however, 1A-rated substitutes provide full compatibility.

Package and Pinout: All substitutes must use the TO-252-3 DPAK package with identical pinout to ensure direct PCB compatibility without layout modifications.

Input Voltage Rating: The maximum input voltage of 35V establishes the upper limit for supply voltage. Substitutes with equal or higher input voltage ratings are acceptable.

Operating Temperature Range: The KA7809ERTF operates from -40°C to 125°C. Substitutes with narrower temperature ranges (such as 0°C to 125°C) are acceptable for applications within that reduced range.

Protection Features: Over Temperature and Short Circuit protection are standard across all listed substitutes, ensuring equivalent safety characteristics.

Parameter Comparison

Engineering Selection Recommendations

Full 1A Current Capability Substitutes:

BA17809FP-E2 (Rohm Semiconductor) is the primary equivalent substitute, offering identical 1A output current and 2V typical dropout voltage matching the KA7809ERTF. This part is Active status with ROHS3 compliance. The maximum input voltage is reduced to 26V, which is acceptable for applications with input supplies below 26V. The operating temperature range is narrower (-40°C to 85°C), limiting use in applications requiring operation above 85°C.

500mA Output Current Substitutes (Active Status):

MC78M09BDTRKG and MC78M09CDTRKG (onsemi) are Active-status alternatives with 500mA output current. Both maintain 35V maximum input voltage and ROHS3 compliance. MC78M09BDTRKG supports the full -40°C to 125°C temperature range, while MC78M09CDTRKG operates from 0°C to 125°C. These parts are suitable for applications where output current does not exceed 500mA.

L78M09CDT-TR (STMicroelectronics) provides 500mA output current with 35V input rating and Active status. This part includes Over Current protection in addition to Over Temperature and Short Circuit protection. Operating temperature range is 0°C to 125°C.

Obsolete Status Substitute:

MC78M09CDTG (onsemi) is Obsolete status with 500mA output current. This part should be avoided for new designs due to product discontinuation status.

Frequently Asked Questions (FAQ)

Q: Can I use a 500mA substitute in place of the 1A-rated KA7809ERTF?

A: Only if your application's maximum output current requirement does not exceed 500mA. If your circuit draws more than 500mA from the 9V rail, the 500mA-rated substitute will not provide adequate current and may enter current-limit protection. For applications requiring the full 1A capability, use BA17809FP-E2.

Q: What is the difference between MC78M09BDTRKG and MC78M09CDTRKG?

A: Both are 500mA onsemi regulators in DPAK packaging with identical electrical characteristics. The primary difference is operating temperature range: MC78M09BDTRKG supports -40°C to 125°C, while MC78M09CDTRKG operates from 0°C to 125°C. Select based on your application's minimum operating temperature requirement.

Q: Why does BA17809FP-E2 have a lower maximum input voltage (26V vs 35V)?

A: BA17809FP-E2 is manufactured by Rohm Semiconductor with different design specifications than the onsemi KA7809ERTF. The 26V maximum input rating is still suitable for most standard power supply applications. If your circuit requires input voltages above 26V, select an alternative with 35V rating such as MC78M09BDTRKG or L78M09CDT-TR.

Q: Are all substitutes in the same DPAK package?

A: Yes. All listed substitutes use the TO-252-3 DPAK (2 Leads + Tab) package with identical pinout, enabling direct PCB replacement without layout modifications.

Q: What does ROHS3 compliance mean for these parts?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. All Active-status substitutes listed are ROHS3 compliant, suitable for applications requiring environmental compliance.

Q: Should I avoid Obsolete-status parts?

A: Yes. For new designs and ongoing production, select only Active-status substitutes: BA17809FP-E2, MC78M09BDTRKG, MC78M09CDTRKG, or L78M09CDT-TR. Obsolete parts have limited availability and no manufacturer support.

Q: Which substitute offers the best PSRR performance?

A: MC78M09BDTRKG and MC78M09CDTRKG both provide 80dB PSRR at 120Hz, superior to the KA7809ERTF's 71dB. This results in better noise rejection on the regulated output. L78M09CDT-TR provides 56dB PSRR, which is lower but still adequate for most applications.