KA78M12RTM Equivalent & Substitute Parts

Part Overview

The KA78M12RTM is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 12V output at 500mA in a DPAK surface mount package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance applications. The device features integrated over-temperature and short-circuit protection, suitable for power management applications requiring stable 12V regulation from input sources up to 35V.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	12V
Output Current	500mA
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 500mA (Typ)
Output Configuration	Positive Fixed
Package Type	TO-252-3 DPAK (2 Leads + Tab)
Mounting Type	Surface Mount
Protection Features	Over Temperature, Short Circuit
Operating Temperature Range	0°C ~ 125°C

Substitute Part Grouping Explanation

Substitution for the KA78M12RTM is determined by the following critical parameters:

Fixed output voltage of 12V
Output current capability of 500mA or higher
Maximum input voltage of 35V or greater
DPAK surface mount package (TO-252-3)
Positive fixed output configuration
Over-temperature and short-circuit protection

Substitute parts are grouped into two categories:

Direct 500mA Equivalents: Parts with identical 500mA output current rating, matching the original specification exactly.

Higher Current Alternatives: Parts rated for 1A output current, which provide enhanced current capability while maintaining all other electrical and mechanical compatibility parameters.

Parameter Comparison

Part Number	Manufacturer	Output Current	Input Voltage (Max)	Output Voltage	Package	Operating Temp	Product Status
KA78M12RTM	onsemi	500mA	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Obsolete
MC78M12ACDTRKG	onsemi	500mA	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Active
MC78M12BDTRKG	onsemi	500mA	35V	12V	TO-252-3 DPAK	-40°C ~ 125°C	Active
MC78M12CDTRKG	onsemi	500mA	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Active
MC78M12CDTG	onsemi	500mA	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Active
MC78M12BDTG	onsemi	500mA	35V	12V	TO-252-3 DPAK	-40°C ~ 125°C	Active
MC78M12ACDTG	onsemi	500mA	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Obsolete
MC7812BDTRKG	onsemi	1A	35V	12V	TO-252-3 DPAK	-40°C ~ 125°C	Active
MC7812CDTRKG	onsemi	1A	35V	12V	TO-252-3 DPAK	0°C ~ 125°C	Active
MC7812BDTG	onsemi	1A	35V	12V	TO-252-3 DPAK	-40°C ~ 125°C	Active

Engineering Selection Recommendations

For Direct Replacement (500mA Output Current):

Select MC78M12CDTRKG or MC78M12ACDTRKG for applications requiring identical electrical specifications to the KA78M12RTM. Both parts are active products with ROHS3 compliance and provide the same 500mA output current in the same DPAK package. MC78M12CDTRKG offers the highest inventory availability (131,200 units) and is supplied in Cut Tape & Digi-Reel packaging, suitable for high-volume production. MC78M12ACDTRKG is available in Tape & Reel format with 1,327 units in stock.

MC78M12BDTRKG provides extended operating temperature range (-40°C to 125°C) compared to the original part (0°C to 125°C), offering improved performance in low-temperature environments while maintaining 500mA output current and active product status.

For Higher Current Applications (1A Output Current):

Select MC7812BDTRKG or MC7812CDTRKG when applications require increased current capacity beyond 500mA. Both parts maintain the 12V fixed output and 35V maximum input voltage. MC7812BDTRKG provides extended temperature range (-40°C to 125°C) with 305,200 units available in Cut Tape & Digi-Reel packaging. MC7812CDTRKG maintains the standard temperature range (0°C to 125°C) with 16,776 units in Tape & Reel format.

All recommended substitutes are manufactured by onsemi, feature ROHS3 compliance, and include identical protection features (over-temperature and short-circuit protection) as the original KA78M12RTM.

Frequently Asked Questions (FAQ)

Q: Can MC7812 series parts (1A rating) directly replace MC78M12 series parts (500mA rating)?

A: Yes. The MC7812 series provides higher output current capability (1A) while maintaining identical output voltage (12V), input voltage rating (35V), and DPAK package configuration. This substitution is electrically compatible and provides enhanced current headroom for the application.

Q: What is the difference between BDTRKG, CDTRKG, BDTG, and CDTG packaging designations?

A: BDTRKG and CDTRKG indicate Tape & Reel or Cut Tape & Digi-Reel packaging for automated assembly. BDTG and CDTG indicate Tube packaging for manual handling. The electrical specifications remain identical; packaging selection depends on production volume and assembly equipment compatibility.

Q: Does the extended temperature range (-40°C to 125°C) of MC78M12BDTRKG affect compatibility?

A: No. The extended temperature range is a superset of the original KA78M12RTM specification (0°C to 125°C). MC78M12BDTRKG operates within the original temperature range and provides additional capability for low-temperature environments.

Q: Are all substitute parts ROHS3 compliant?

A: All active substitute parts listed (MC78M12 and MC7812 series) are ROHS3 compliant. The original KA78M12RTM is obsolete and does not carry ROHS3 certification.

Q: What inventory considerations should guide part selection?

A: MC78M12CDTRKG offers the highest inventory availability (131,200 units), making it the preferred choice for high-volume production. MC7812BDTRKG provides 305,200 units for 1A applications. Smaller inventory quantities are available for alternative packaging formats.

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