KA7809ETSTU Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The KA7809ETSTU 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, maintenance, and production continuity. The regulator includes over-temperature and short-circuit protection features suitable for general-purpose power management applications requiring stable 9V regulation from input sources up to 35V.

Key Parameters

Parameter	Value
Manufacturer Part Number	KA7809ETSTU
Manufacturer	onsemi
Output Voltage (Fixed)	9V
Output Current	1A
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 1A (Typ)
Quiescent Current	8 mA
PSRR	71dB (120Hz)
Package / Case	TO-220-3
Mounting Type	Through Hole
Operating Temperature	-40°C ~ 125°C
Protection Features	Over Temperature, Short Circuit
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitute parts for the KA7809ETSTU are classified based on strict electrical and mechanical compatibility criteria. The primary substitution parameters are:

Output voltage: 9V fixed (non-negotiable)
Output current capacity: 1A minimum
Input voltage rating: 35V maximum
Package type: TO-220-3 through-hole configuration
Voltage dropout: 2V @ 1A or better
Protection features: Over-temperature and short-circuit protection

Substitutes are grouped into two categories:

Direct Electrical Equivalents (1A Output Current): Parts meeting all primary electrical specifications with identical 1A output current rating. These include MC7809ACTG, MC7809CTG, MC7809BTG, BA7809CP-E2, and L7809ABV-DG.

Higher Current Capacity Alternatives (500mA to 2A Output): Parts with the same 9V output and TO-220-3 package but different current ratings. These include MC78M09CTG (500mA), L78M09CV (500mA), and L78S09CV (2A). These are suitable when the application can tolerate lower current capacity or when higher current capacity provides design margin.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	PSRR (120Hz)	Operating Temp	Package	Product Status
KA7809ETSTU	onsemi	9V	1A	35V	2V @ 1A	8 mA	71dB	-40°C ~ 125°C	TO-220-3	Obsolete
MC7809ACTG	onsemi	9V	1A	35V	2V @ 1A	6 mA	61dB	0°C ~ 125°C	TO-220-3	Obsolete
MC7809CTG	onsemi	9V	1A	35V	2V @ 1A	8 mA	61dB	0°C ~ 125°C	TO-220-3	Active
MC78M09CTG	onsemi	9V	500mA	35V	—	—	80dB	0°C ~ 125°C	TO-220-3	Obsolete
BA7809CP-E2	Rohm Semiconductor	9V	1A	26V	2V @ 1A	8 mA	64dB	-40°C ~ 85°C	TO-220-3 (Cropped Leads)	Obsolete
L7809ABV-DG	STMicroelectronics	9V	1.5A	35V	2V @ 1A	6 mA	61dB	-40°C ~ 125°C	TO-220-3	Obsolete
L7809CV	STMicroelectronics	9V	1.5A	35V	2V @ 1A	8 mA	55dB	0°C ~ 125°C	TO-220-3	Obsolete
L78M09CV	STMicroelectronics	9V	500mA	35V	—	6 mA	56dB	0°C ~ 125°C	TO-220-3	Obsolete
L78S09CV	STMicroelectronics	9V	2A	35V	—	8 mA	47dB	0°C ~ 150°C	TO-220-3	Obsolete
MC7809BTG	onsemi	9V	1A	35V	2V @ 1A	8 mA	61dB	-40°C ~ 125°C	TO-220-3	Obsolete

Engineering Selection Recommendations

Primary Substitute (Recommended for Direct Replacement): MC7809CTG is the preferred substitute. It maintains identical electrical specifications to the KA7809ETSTU (9V output, 1A current, 35V input maximum, 2V dropout), operates across the same temperature range, and holds Active product status, ensuring long-term availability and supply chain continuity. RoHS3 compliance provides regulatory alignment for modern manufacturing environments.

Alternative Substitutes with Extended Current Capacity: L7809ABV-DG and L7809CV from STMicroelectronics provide 1.5A output current, offering design margin for applications approaching the 1A limit. Both maintain 35V input rating and 2V dropout specification. L7809ABV-DG supports the full -40°C to 125°C temperature range matching the original part.

Substitutes with Reduced Current Capacity: MC78M09CTG and L78M09CV deliver 500mA output current. These are suitable only for applications with confirmed current requirements below 500mA and should not be used as direct replacements in designs requiring full 1A capacity.

Higher Current Alternative: L78S09CV provides 2A output capacity with extended operating temperature to 150°C, suitable for applications requiring additional thermal headroom or current margin beyond the original 1A specification.

Mechanical Consideration: BA7809CP-E2 features cropped leads (TO-220CP-3 package variant) and reduced input voltage rating (26V maximum). This part is suitable only when PCB layout specifically requires cropped-lead configuration and input voltage remains below 26V.

Frequently Asked Questions (FAQ)

Q: Can MC7809CTG directly replace KA7809ETSTU without circuit modification?

A: Yes. MC7809CTG maintains identical electrical specifications: 9V fixed output, 1A current capacity, 35V maximum input, and 2V dropout voltage. The TO-220-3 package pinout is identical. No circuit changes are required. The primary difference is operating temperature range (0°C to 125°C versus -40°C to 125°C), which is acceptable for most applications not requiring sub-zero operation.

Q: What is the difference between MC7809CTG and MC7809ACTG?

A: Both are onsemi 9V/1A regulators in TO-220-3 packages. MC7809CTG is currently Active in production with 23,318 units in stock. MC7809ACTG is Obsolete with lower inventory (1,685 units). MC7809ACTG has slightly lower quiescent current (6 mA versus 8 mA) and lower PSRR (61dB versus 61dB). For new designs, MC7809CTG is preferred due to active status.

Q: Can I use L7809ABV-DG or L7809CV as substitutes?

A: Yes, both are suitable substitutes. These STMicroelectronics parts provide 1.5A output current, exceeding the original 1A specification. They maintain 9V output, 35V input maximum, and 2V dropout. L7809ABV-DG supports -40°C to 125°C operation matching the original temperature range. L7809CV operates 0°C to 125°C. Both are electrically compatible without circuit modification.

Q: Why would I choose MC78M09CTG or L78M09CV (500mA versions)?

A: These lower-current variants are suitable only when application current requirements are confirmed below 500mA. They should not be used as direct replacements in designs requiring full 1A capacity. Use only when design analysis confirms maximum load current does not exceed 500mA.

Q: Is the BA7809CP-E2 a suitable replacement?

A: BA7809CP-E2 is mechanically and electrically compatible for most applications. However, it has two limiting factors: maximum input voltage is 26V (versus 35V for the original), and operating temperature range is -40°C to 85°C (versus -40°C to 125°C). Use only when input voltage remains below 26V and operating temperature does not exceed 85°C.

Q: What does "cropped leads" mean on the BA7809CP-E2?

A: The BA7809CP-E2 uses TO-220CP-3 package with shortened leads designed for specific PCB layouts requiring reduced lead length. Standard TO-220-3 packages have full-length leads. Verify PCB footprint compatibility before selecting this variant.

Q: Can L78S09CV (2A version) be used instead of the 1A original?

A: Yes, L78S09CV is electrically compatible and provides higher current capacity (2A versus 1A), offering design margin. It maintains 9V output and 35V input maximum. Operating temperature extends to 150°C. Use when additional current capacity or thermal margin is beneficial. No circuit modification is required.

Q: What is PSRR and why does it vary among substitutes?

A: PSRR (Power Supply Rejection Ratio) measures how effectively the regulator rejects input voltage ripple. Higher PSRR values indicate better noise rejection. The KA7809ETSTU has 71dB PSRR, while most substitutes range from 47dB to 80dB. For applications sensitive to input ripple, select substitutes with PSRR values closest to or exceeding the original specification.

Q: Are all these parts RoHS compliant?

A: All substitute parts listed carry RoHS3 compliance certification, meeting current environmental and regulatory requirements for electronic component manufacturing and use.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message