MC7809ECTBU Equivalent & Substitute Parts

Part Overview

The MC7809ECTBU 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 component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and production continuity. The regulator includes over-temperature and short-circuit protection features suitable for general-purpose power management applications.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	9V
Output Current	1A
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 1A (Typ)
Quiescent Current	8 mA
Operating Temperature Range	0°C ~ 125°C
Package / Case	TO-220-3
Mounting Type	Through Hole
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution for the MC7809ECTBU is determined by the following critical parameters:

Output voltage: 9V fixed
Output current capability: 1A or greater
Input voltage rating: 35V maximum
Package type: TO-220-3 through-hole
Protection features: Over-temperature and short-circuit protection

Substitute parts are grouped into two categories:

Direct Substitutes (1A Output Current): Parts with identical 1A output current rating, matching the original specification exactly.

Higher Current Alternatives (500mA to 2A Output Current): Parts with output current ratings below or above 1A. Lower-current parts (500mA) are suitable only for applications with reduced current requirements. Higher-current parts (1.5A, 2A) provide additional headroom and are backward-compatible with 1A designs.

Parameter Comparison

Part Number	Manufacturer	Output Current	Quiescent Current (mA)	PSRR (dB @ 120Hz)	Operating Temp Range	Product Status	RoHS Status
MC7809ECTBU	onsemi	1A	8	71	0°C ~ 125°C	Obsolete	REACH Unaffected
MC7809ACTG	onsemi	1A	6	61	0°C ~ 125°C	Obsolete	ROHS3 Compliant
MC7809CTG	onsemi	1A	8	61	0°C ~ 125°C	Active	ROHS3 Compliant
MC78M09CTG	onsemi	500mA	—	80	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L7809ABV-DG	STMicroelectronics	1.5A	6	61	-40°C ~ 125°C	Obsolete	ROHS3 Compliant
L7809CV	STMicroelectronics	1.5A	8	55	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L78M09CV	STMicroelectronics	500mA	6	56	0°C ~ 125°C	Obsolete	ROHS3 Compliant
L78S09CV	STMicroelectronics	2A	8	47	0°C ~ 150°C	Obsolete	ROHS3 Compliant
MC7809BTG	onsemi	1A	8	61	-40°C ~ 125°C	Obsolete	ROHS3 Compliant
KA7809AETU	Fairchild Semiconductor	1A	6	58	0°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

Recommended Primary Substitute: MC7809CTG (onsemi)

MC7809CTG is the preferred substitute for the MC7809ECTBU. Both parts share identical electrical specifications (1A output, 9V fixed, 35V input maximum, 2V dropout at 1A), matching package type (TO-220-3), and protection features. MC7809CTG holds Active product status and ROHS3 compliance, ensuring long-term availability and regulatory alignment. This part provides direct functional equivalence with no design modifications required.

Secondary Substitute: KA7809AETU (Fairchild Semiconductor)

KA7809AETU is a parametric equivalent with Active product status. It matches the MC7809ECTBU in output current (1A), voltage specifications, and package type. Quiescent current is lower (6mA vs. 8mA), and PSRR is slightly reduced (58dB vs. 71dB). This part is suitable for applications where component availability from multiple manufacturers is required.

Higher Current Alternatives: L7809ABV-DG, L7809CV, L78S09CV (STMicroelectronics)

These parts provide increased output current capacity (1.5A to 2A) while maintaining 9V fixed output and 35V input maximum. They are backward-compatible with 1A designs and suitable for applications requiring additional current headroom. L78S09CV extends the operating temperature range to 150°C.

Lower Current Alternative: MC78M09CTG, L78M09CV (500mA Output)

These parts are suitable only for applications with reduced current requirements below 1A. They are not recommended as direct replacements for 1A-rated designs.

Frequently Asked Questions (FAQ)

Q: Can MC7809CTG directly replace MC7809ECTBU without circuit modifications?

A: Yes. MC7809CTG is a direct functional equivalent with identical output voltage (9V), output current (1A), input voltage rating (35V), dropout voltage (2V @ 1A), and TO-220-3 package. No circuit modifications are required.

Q: What is the difference between MC7809ECTBU and MC7809ACTG?

A: Both parts provide 1A output at 9V with identical input voltage and dropout specifications. MC7809ACTG has lower quiescent current (6mA vs. 8mA) and lower PSRR (61dB vs. 71dB). Both are obsolete; MC7809CTG is the recommended active alternative.

Q: Can I use L7809CV (1.5A) instead of MC7809ECTBU (1A)?

A: Yes. L7809CV provides higher output current capacity (1.5A) and is backward-compatible with 1A designs. It maintains the same 9V output, 35V input maximum, and TO-220-3 package. This substitution is suitable for applications requiring additional current margin.

Q: What is the difference between L78S09CV (2A) and MC7809ECTBU (1A)?

A: L78S09CV provides double the output current (2A vs. 1A) and extends the operating temperature range to 150°C. It maintains 9V output and TO-220-3 package compatibility. PSRR is lower (47dB vs. 71dB). This part is suitable for high-current applications or extended temperature environments.

Q: Are 500mA parts (MC78M09CTG, L78M09CV) suitable replacements?

A: No. These parts have half the output current rating (500mA vs. 1A) and are not suitable as direct replacements for 1A designs. They are only appropriate for applications with reduced current requirements.

Q: What is the significance of product status (Active vs. Obsolete)?

A: Active parts have guaranteed long-term availability and manufacturer support. Obsolete parts may have limited stock and no future production. MC7809CTG and KA7809AETU are Active and recommended for new designs. Obsolete parts are suitable for legacy system maintenance only.

Q: Does RoHS compliance affect substitution?

A: MC7809ECTBU is REACH Unaffected. Substitute parts with ROHS3 Compliant status are suitable for applications requiring RoHS compliance. This does not affect electrical compatibility.

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