KA7812E Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The KA7812E is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 12V output at 1A current capacity in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The KA7812E serves applications requiring stable 12V regulation from input sources up to 35V with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	12V
Output Current	1A
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 1A (Typ)
Quiescent Current (Iq)	8 mA
Operating Temperature Range	-40°C ~ 125°C
Package / Case	TO-220-3
Protection Features	Over Temperature, Short Circuit
Output Configuration	Positive Fixed

Substitute Part Grouping Explanation

Substitute parts for the KA7812E are classified into two functional categories based on electrical compatibility:

Category 1: Direct Equivalents (1A Output Current) Parts meeting all critical parameters: 12V fixed output, 1A output current, 35V maximum input voltage, TO-220-3 package, -40°C to 125°C operating range, and integrated thermal and short-circuit protection. These parts are pin-compatible and functionally interchangeable without circuit modification.

Category 2: Reduced Current Alternatives (500mA Output Current) Parts with identical voltage regulation characteristics but reduced output current capacity (500mA instead of 1A). These are suitable only for applications where load current does not exceed 500mA. Package and protection features remain compatible.

Category 3: Enhanced Current Capability (1.5A Output Current) Parts exceeding the original 1A specification with 1.5A output capacity. These provide additional design margin and are backward-compatible for applications requiring the original 1A or less.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Iq (mA)	Temp Range	Package	Product Status
KA7812E	onsemi	12V	1A	35V	2V @ 1A	8	-40°C ~ 125°C	TO-220-3	Obsolete
MC7812BTG	onsemi	12V	1A	35V	2V @ 1A	8	-40°C ~ 125°C	TO-220-3	Active
MC7812ACTG	onsemi	12V	1A	35V	2V @ 1A	6	0°C ~ 125°C	TO-220-3	Active
MC7812CTG	onsemi	12V	1A	35V	2V @ 1A	6.5	0°C ~ 125°C	TO-220-3	Active
AS7812AT-E1	Diodes Incorporated	12V	1A	32V	2V @ 1A	6	-40°C ~ 125°C	TO-220-3	Active
L7812ABV	STMicroelectronics	12V	1.5A	35V	2V @ 1A	6	-40°C ~ 125°C	TO-220-3	Active
L7812ACV	STMicroelectronics	12V	1.5A	35V	2V @ 1A	6	0°C ~ 125°C	TO-220-3	Active
L7812CV	UMW	12V	1.2A	35V	—	6	-40°C ~ 105°C	TO-220-3	Active
MC78M12ACTG	onsemi	12V	500mA	35V	—	—	0°C ~ 125°C	TO-220-3	Obsolete
MC78M12BTG	onsemi	12V	500mA	35V	—	—	-40°C ~ 125°C	TO-220-3	Active
MC78M12CTG	onsemi	12V	500mA	35V	—	—	0°C ~ 125°C	TO-220-3	Active

Engineering Selection Recommendations

Primary Recommendation: MC7812BTG The MC7812BTG from onsemi is the direct active equivalent to the obsolete KA7812E. It maintains identical electrical specifications (12V output, 1A current, 35V input maximum, 2V dropout) and extended temperature range (-40°C to 125°C). This part carries ROHS3 compliance and is available in high volume (45,100 units in stock), making it the preferred choice for direct replacement in existing designs.

Alternative for Extended Temperature: L7812ABV or L7812ACV STMicroelectronics L7812 series parts provide enhanced output current (1.5A) while maintaining full compatibility with the KA7812E pinout and voltage specifications. The L7812ABV supports the full -40°C to 125°C range, while L7812ACV operates from 0°C to 125°C. Both are ROHS3 compliant and suitable for applications requiring additional current margin.

Alternative for Reduced Current Applications: MC78M12BTG For applications where load current does not exceed 500mA, the MC78M12BTG provides a lower-cost alternative with identical voltage regulation and protection features. This part is active and ROHS3 compliant with -40°C to 125°C operating range.

Cross-Manufacturer Option: AS7812AT-E1 Diodes Incorporated AS7812AT-E1 offers 1A output current with full temperature range support (-40°C to 125°C). Input voltage maximum is 32V (3V lower than the original specification). This part is suitable only if the application input voltage does not exceed 32V.

Compliance Considerations All recommended active substitutes carry ROHS3 compliance certification. The KA7812E and MC78M12ACTG are classified as obsolete; active alternatives should be prioritized for new designs. All parts maintain REACH Unaffected status and EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can MC7812ACTG or MC7812CTG be used as direct replacements for KA7812E? A: Yes, both parts are pin-compatible direct equivalents with identical 12V output and 1A current specifications. MC7812BTG is preferred due to extended -40°C to 125°C temperature range, while MC7812ACTG and MC7812CTG operate from 0°C to 125°C.

Q: What is the difference between MC7812BTG and MC78M12BTG? A: MC7812BTG provides 1A output current, while MC78M12BTG provides 500mA. Both maintain 12V output voltage and TO-220-3 packaging. Select MC78M12BTG only if application load current is confirmed below 500mA.

Q: Can L7812ABV replace KA7812E in all applications? A: Yes. L7812ABV provides 1.5A output current (exceeding the original 1A specification) with identical 12V output, 35V input maximum, and -40°C to 125°C operating range. It is pin-compatible and suitable for all KA7812E applications.

Q: Is AS7812AT-E1 suitable for all KA7812E applications? A: AS7812AT-E1 is suitable only if application input voltage does not exceed 32V. The original KA7812E and most alternatives support 35V input maximum. Verify input voltage specifications before selection.

Q: What is the impact of quiescent current differences between parts? A: Quiescent current (Iq) ranges from 6 mA to 8 mA across the substitute parts. This difference is negligible in most applications and does not affect functional compatibility. Lower Iq values (6 mA) provide marginal power efficiency improvement in standby conditions.

Q: Are all substitute parts ROHS3 compliant? A: All active substitute parts listed carry ROHS3 compliance. The original KA7812E and MC78M12ACTG are classified as obsolete and do not carry ROHS3 certification. Use active alternatives for new designs requiring ROHS3 compliance.

Q: Can reduced-current parts (500mA) be used in place of 1A parts? A: No. Reduced-current parts (MC78M12 series) are suitable only for applications where maximum load current does not exceed 500mA. Using them in higher-current applications will cause thermal shutdown or voltage regulation failure.

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