MC78M08ABTG Equivalent & Substitute Parts

Part Overview

The MC78M08ABTG is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 8V output at 500mA in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and component procurement. The MC78M08ABTG serves applications requiring stable 8V regulation with moderate current capacity and integrated thermal and short-circuit protection.

Key Parameters

Parameter	Value
Manufacturer	onsemi
Part Number	MC78M08ABTG
Category	Power Management (PMIC)
Output Voltage (Fixed)	8V
Output Current	500mA
Input Voltage (Max)	35V
Package / Case	TO-220-3
Mounting Type	Through Hole
Operating Temperature	-40°C ~ 125°C
Protection Features	Over Temperature, Short Circuit
PSRR	80dB (120Hz)
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the MC78M08ABTG is determined by the following critical parameters:

Fixed Substitution Criteria:

Output voltage: 8V (fixed)
Package type: TO-220-3 (through-hole mounting)
Output configuration: Positive
Number of regulators: 1
RoHS compliance: ROHS3 Compliant
REACH status: REACH Unaffected

Flexible Substitution Parameters:

Output current capacity: 500mA minimum (higher ratings acceptable)
Input voltage maximum: 25V to 35V range acceptable
Operating temperature range: 0°C to 125°C acceptable (original: -40°C to 125°C)
PSRR: 56dB to 80dB acceptable
Protection features: Over Temperature and Short Circuit required

Substitute parts are grouped into two categories based on current capacity: 500mA-rated devices (direct equivalents) and 1.5A-rated devices (higher-capacity alternatives).

Parameter Comparison

Parameter	MC78M08ABTG (onsemi)	UA78M08CKCS (TI)	UA78M08CKCSE3 (TI)	L7808CV (STM)	L7808ABV (STM)	L7808ACV (STM)
Output Voltage	8V	8V	8V	8V	8V	8V
Output Current	500mA	500mA	500mA	1.5A	1.5A	1.5A
Input Voltage (Max)	35V	25V	25V	35V	35V	35V
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Operating Temperature	-40°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	0°C ~ 125°C	-40°C ~ 125°C	0°C ~ 125°C
PSRR (120Hz)	80dB	80dB	80dB	56dB	62dB	62dB
Protection Features	Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Current, Over Temperature, Short Circuit	Over Temperature, Short Circuit	Over Temperature, Short Circuit	Over Temperature, Short Circuit
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole

Engineering Selection Recommendations

Direct Equivalents (500mA Output Current):

UA78M08CKCS and UA78M08CKCSE3 (Texas Instruments) are direct functional equivalents with identical 500mA output current and 80dB PSRR. Both devices are ROHS3 compliant and obsolete. The primary difference is input voltage maximum: these parts are rated to 25V versus the MC78M08ABTG's 35V. Selection of these parts is appropriate for applications where input voltage does not exceed 25V. UA78M08CKCSE3 includes over-current protection in addition to thermal and short-circuit protection.

Higher-Capacity Alternatives (1.5A Output Current):

L7808CV, L7808ABV, and L7808ACV (STMicroelectronics) provide 1.5A output current capacity in the same TO-220-3 package. These parts are suitable for applications requiring higher current delivery or where design margin is necessary. All three are ROHS3 compliant and obsolete. L7808ABV and L7808ACV maintain the -40°C to 125°C operating range of the original part (L7808CV operates 0°C to 125°C). PSRR values range from 56dB to 62dB, lower than the original 80dB specification.

Compliance Basis:

All substitute parts meet ROHS3 compliance and REACH unaffected status, matching the original device. Selection should prioritize parts with operating temperature ranges and input voltage ratings compatible with the target application requirements.

Frequently Asked Questions (FAQ)

Q: Can I use a 1.5A-rated regulator as a substitute for the 500mA MC78M08ABTG?

A: Yes. Higher current-rated regulators (L7808CV, L7808ABV, L7808ACV) are functionally compatible substitutes. The 1.5A rating provides additional current capacity and design margin. The TO-220-3 package and pinout are identical, and all devices deliver the same fixed 8V output. Thermal management may improve due to lower power dissipation at equivalent load currents.

Q: What is the difference between UA78M08CKCS and UA78M08CKCSE3?

A: Both are Texas Instruments 500mA regulators with identical output voltage, current, and PSRR specifications. UA78M08CKCSE3 includes over-current protection in addition to thermal and short-circuit protection. The primary difference is packaging designation; UA78M08CKCSE3 is specified as tube packaging.

Q: Are there temperature range limitations when substituting?

A: The MC78M08ABTG operates from -40°C to 125°C. Substitute parts operate from 0°C to 125°C (most STMicroelectronics and some Texas Instruments parts) or -40°C to 125°C (L7808ABV). For applications requiring operation below 0°C, L7808ABV is the appropriate selection.

Q: What is the input voltage limitation for Texas Instruments substitutes?

A: UA78M08CKCS and UA78M08CKCSE3 are rated to 25V maximum input voltage, compared to the MC78M08ABTG's 35V rating. These parts are suitable for applications with input voltages up to 25V. For applications exceeding 25V input, use STMicroelectronics alternatives (L7808CV, L7808ABV, L7808ACV) rated to 35V.

Q: Is the TO-220-3 package identical across all substitute parts?

A: Yes. All substitute parts use the TO-220-3 package with identical pinout and through-hole mounting. Direct mechanical and electrical substitution is possible without PCB modification.

Q: Do all substitute parts meet RoHS compliance?

A: Yes. All listed substitute parts are ROHS3 compliant and REACH unaffected, matching the original MC78M08ABTG specification.

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