KA78M12TU Linear Voltage Regulator 12V 500mA Equivalent & Substitute Parts

Part Overview

The KA78M12TU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 12V output at 500mA in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. The KA78M12TU serves applications requiring regulated 12V power from input sources up to 35V, with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Manufacturer	onsemi
Part Number	KA78M12TU
Output Voltage (Fixed)	12V
Output Current	500mA
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 500mA (Typ)
Quiescent Current	6 mA
PSRR	80dB (120Hz)
Protection Features	Over Temperature, Short Circuit
Operating Temperature	0°C ~ 125°C
Package	TO-220-3
Mounting Type	Through Hole
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the KA78M12TU is determined by the following critical parameters:

Output voltage: 12V fixed
Output current capability: 500mA minimum
Package type: TO-220-3 (through-hole)
Input voltage rating: 30V minimum
Protection features: Over-temperature and short-circuit protection
Operating temperature range: 0°C minimum to 125°C maximum

Substitute parts are grouped into three categories:

Direct Equivalents (500mA Output): Parts with identical 500mA output current rating and matching electrical specifications
Higher Current Alternatives (1A Output): Parts with 1A output capability, suitable for applications with headroom requirements
Cross-Manufacturer Alternatives: Functionally equivalent parts from different manufacturers meeting the same electrical and mechanical criteria

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Voltage Dropout (Max)	Quiescent Current	PSRR	Operating Temp	Product Status	Package
KA78M12TU	onsemi	500mA	35V	2V @ 500mA	6 mA	80dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3
MC78M12ACTG	onsemi	500mA	35V	—	—	80dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3
MC78M12BTG	onsemi	500mA	35V	—	—	80dB (120Hz)	-40°C ~ 125°C	Active	TO-220-3
MC78M12CTG	onsemi	500mA	35V	—	—	80dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
L78M12CV	STMicroelectronics	500mA	35V	—	6 mA	55dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
UA78M12CKCS	Texas Instruments	500mA	30V	2V @ 350mA	—	80dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3
MC7812ACTG	onsemi	1A	35V	2V @ 1A	6 mA	60dB (1kHz)	0°C ~ 125°C	Active	TO-220-3
MC7812BTG	onsemi	1A	35V	2V @ 1A	8 mA	60dB (1kHz)	-40°C ~ 125°C	Active	TO-220-3
MC7812CTG	onsemi	1A	35V	2V @ 1A	6.5 mA	60dB (1kHz)	0°C ~ 125°C	Active	TO-220-3
AS7812AT-E1	Diodes Incorporated	1A	32V	2V @ 1A	6 mA	60dB (120Hz)	-40°C ~ 125°C	Active	TO-220-3
L7812ABV	STMicroelectronics	1.5A	35V	2V @ 1A	6 mA	60dB (120Hz)	-40°C ~ 125°C	Active	TO-220-3

Engineering Selection Recommendations

Direct Replacement (500mA Rating):

MC78M12CTG is the preferred direct replacement. It is manufactured by onsemi, maintains identical 500mA output current and 12V fixed output voltage, operates within the same 0°C to 125°C temperature range, and carries active product status with RoHS3 compliance. This part provides the closest functional equivalence to the obsolete KA78M12TU.

L78M12CV from STMicroelectronics is an alternative direct replacement with active product status and RoHS3 compliance. It maintains 500mA output current and 12V output voltage with identical input voltage rating of 35V. The PSRR specification is lower (55dB vs. 80dB at 120Hz), which may be relevant for noise-sensitive applications.

MC78M12BTG offers extended operating temperature range (-40°C to 125°C) compared to the original part, with active product status and RoHS3 compliance. This part is suitable for applications requiring wider temperature operation.

Higher Current Alternatives (1A Rating):

MC7812ACTG, MC7812BTG, and MC7812CTG from onsemi provide 1A output current capability while maintaining 12V fixed output and 35V maximum input voltage. These parts are suitable for applications where the original 500mA specification provides insufficient margin. All three carry active product status and RoHS3 compliance.

AS7812AT-E1 from Diodes Incorporated provides 1A output current with extended temperature range (-40°C to 125°C) and active product status. Input voltage rating is 32V, which is acceptable for most applications but represents a 3V reduction from the original 35V specification.

L7812ABV from STMicroelectronics provides 1.5A output current with extended temperature range (-40°C to 125°C) and active product status. This part offers the highest current capability among available alternatives.

Compliance Considerations:

All recommended substitute parts carry RoHS3 compliance and REACH Unaffected status, matching the regulatory profile of the original KA78M12TU. Parts with active product status are preferred for new designs to ensure long-term availability and supply chain stability.

Frequently Asked Questions (FAQ)

Q: Can MC7812ACTG replace KA78M12TU directly?

A: MC7812ACTG is functionally compatible but provides 1A output current versus the original 500mA specification. It maintains identical 12V output voltage, 35V maximum input voltage, and TO-220-3 package. The higher current rating makes it suitable for applications with increased power requirements. Pin configuration and electrical interface are compatible.

Q: What is the difference between MC78M12CTG and MC78M12BTG?

A: Both parts provide 500mA output current and 12V fixed output voltage in TO-220-3 package. MC78M12BTG operates across -40°C to 125°C temperature range, while MC78M12CTG operates across 0°C to 125°C. MC78M12BTG is preferred for applications requiring extended low-temperature operation. Quiescent current differs slightly (8 mA vs. 6.5 mA).

Q: Is L78M12CV from STMicroelectronics a suitable replacement?

A: L78M12CV is a suitable direct replacement maintaining 500mA output current, 12V fixed output voltage, and TO-220-3 package. It carries active product status and RoHS3 compliance. The PSRR specification is 55dB at 120Hz compared to 80dB for the original part. This lower PSRR may affect performance in noise-sensitive applications but is acceptable for general-purpose 12V regulation.

Q: Can I use a 1A rated part in place of the 500mA KA78M12TU?

A: Yes. Parts rated for 1A or higher output current are backward compatible with applications designed for 500mA. The higher current rating provides additional design margin and does not negatively affect circuit operation. Pin configuration and electrical interface remain identical. This approach is recommended for new designs to improve supply chain flexibility.

Q: What is the significance of the TO-220-3 package specification?

A: TO-220-3 is a through-hole package with three leads: input, ground, and output. All substitute parts listed maintain this package type, ensuring mechanical and electrical compatibility with existing PCB layouts and thermal management solutions. Package compatibility is critical for direct board-level replacement without redesign.

Q: Why is the KA78M12TU classified as obsolete?

A: Obsolete status indicates the manufacturer has discontinued production. Existing inventory may be available from authorized distributors, but long-term supply cannot be guaranteed. Transition to active product alternatives such as MC78M12CTG or L78M12CV is recommended for new designs and ongoing production.

Q: Are there temperature range considerations for substitute selection?

A: The original KA78M12TU operates 0°C to 125°C. Substitute parts with identical temperature range (MC78M12CTG, L78M12CV) are direct replacements. Parts with extended range (-40°C to 125°C) such as MC78M12BTG and L7812ABV are suitable for applications requiring wider temperature operation. Parts with narrower ranges are not recommended as replacements.

Q: What does PSRR specification mean in regulator selection?

A: PSRR (Power Supply Rejection Ratio) measures the regulator's ability to reject input voltage ripple and noise. Higher PSRR values indicate better noise rejection. The original KA78M12TU specifies 80dB at 120Hz. Substitute parts with identical or higher PSRR maintain equivalent noise performance. L78M12CV with 55dB PSRR has lower noise rejection and may require additional input filtering in noise-sensitive applications.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message