MC7808ECTBU Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The MC7808ECTBU is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 8V output at 1A current capacity in a TO-220-3 package. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The MC7808ECTBU serves as a positive fixed output regulator suitable for applications requiring stable 8V power delivery with integrated over-temperature and short-circuit protection.

Key Parameters

Parameter	Value
Manufacturer Part Number	MC7808ECTBU
Manufacturer	onsemi
Output Voltage (Fixed)	8V
Output Current	1A
Input Voltage (Max)	35V
Voltage Dropout (Max)	2V @ 1A (Typ)
Quiescent Current	8 mA
PSRR	73dB (120Hz)
Protection Features	Over Temperature, Short Circuit
Operating Temperature Range	0°C ~ 125°C
Package / Case	TO-220-3
Mounting Type	Through Hole
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the MC7808ECTBU is determined by the following critical parameters:

Primary Substitution Criteria:

Fixed output voltage of 8V
Output current rating of 1A or greater
Maximum input voltage of 35V or greater
TO-220-3 or compatible TO-220 package
Positive output configuration
Over-temperature and short-circuit protection

Substitution Categories:

Category 1: Direct Equivalents (1A Output) Parts meeting all primary criteria with 1A output rating: MC7808CTG, MC7808ABTG, UA7808CKCS

Category 2: Higher Current Capability (1.5A Output) Parts with enhanced current capacity suitable for applications requiring additional headroom: L7808ABV, L7808ABV-DG, L7808ACV, L7808ACV-DG, L7808CV

Category 3: Reduced Current Capability (500mA Output) Parts with lower current ratings for applications with reduced power requirements: MC78M08ABTG, MC78M08CTG

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Dropout Voltage	Quiescent Current	PSRR (120Hz)	Operating Temp	Package	Product Status
MC7808ECTBU	onsemi	8V	1A	35V	2V @ 1A	8 mA	73dB	0°C ~ 125°C	TO-220-3	Obsolete
MC7808CTG	onsemi	8V	1A	35V	2V @ 1A	8 mA	62dB	0°C ~ 125°C	TO-220-3	Active
MC7808ABTG	onsemi	8V	1A	35V	2V @ 1A	6 mA	62dB	-40°C ~ 125°C	TO-220-3	Obsolete
L7808ABV	STMicroelectronics	8V	1.5A	35V	2V @ 1A	6 mA	62dB	-40°C ~ 125°C	TO-220-3	Obsolete
L7808ABV-DG	STMicroelectronics	8V	1.5A	35V	2V @ 1A	6 mA	62dB	-40°C ~ 125°C	TO-220-3	Obsolete
L7808ACV	STMicroelectronics	8V	1.5A	35V	2V @ 1A	6 mA	62dB	0°C ~ 125°C	TO-220-3	Obsolete
L7808ACV-DG	STMicroelectronics	8V	1.5A	35V	2V @ 1A	6 mA	62dB	0°C ~ 125°C	TO-220-3	Active
L7808CV	STMicroelectronics	8V	1.5A	35V	2V @ 1A	8 mA	56dB	0°C ~ 125°C	TO-220-3	Obsolete
UA7808CKCS	Texas Instruments	8V	1.5A	25V	2V @ 1A	Not specified	72dB ~ 62dB	0°C ~ 125°C	TO-220-3	Obsolete
MC78M08ABTG	onsemi	8V	500mA	35V	Not specified	Not specified	80dB	-40°C ~ 125°C	TO-220-3	Obsolete
MC78M08CTG	onsemi	8V	500mA	35V	Not specified	Not specified	80dB	0°C ~ 125°C	TO-220-3	Obsolete

Engineering Selection Recommendations

Primary Recommendation: MC7808CTG The MC7808CTG is the preferred direct substitute for the MC7808ECTBU. Both parts share identical electrical specifications (8V output, 1A current, 35V maximum input, 2V dropout voltage), matching package configuration (TO-220-3), and equivalent protection features. The MC7808CTG holds Active product status, ensuring long-term availability and supply chain continuity. This part is manufactured by onsemi, the same supplier as the original component, minimizing design integration risk.

Secondary Recommendation: L7808ACV-DG The L7808ACV-DG from STMicroelectronics provides enhanced current capability (1.5A versus 1A) while maintaining all critical electrical parameters. This part carries Active product status and RoHS3 compliance certification. The higher current rating provides design margin for applications approaching the 1A limit of the original part. Operating temperature range matches the MC7808ECTBU (0°C ~ 125°C).

Alternative for Extended Temperature Range: MC7808ABTG or L7808ABV Applications requiring extended operating temperature range (-40°C ~ 125°C) should consider MC7808ABTG (onsemi) or L7808ABV (STMicroelectronics). Both parts maintain 8V output and 1A or greater current capacity. Note that both parts carry Obsolete status, requiring verification of long-term availability.

Current-Limited Applications: MC78M08CTG Applications with maximum current requirements of 500mA may use MC78M08CTG, which provides equivalent voltage regulation with reduced current rating. This part offers superior PSRR performance (80dB versus 73dB) and maintains TO-220-3 package compatibility.

Input Voltage Constraint: UA7808CKCS The UA7808CKCS from Texas Instruments features a reduced maximum input voltage specification (25V versus 35V). This part is suitable only for applications where input voltage does not exceed 25V. The part carries Obsolete status.

Frequently Asked Questions (FAQ)

Q: Can I use a 1.5A rated part as a direct substitute for the 1A MC7808ECTBU? A: Yes. Parts rated for 1.5A output current (L7808ABV, L7808ACV, L7808ACV-DG, L7808CV, UA7808CKCS) are fully compatible with applications designed for 1A. The higher current rating provides additional design margin without affecting voltage regulation or protection characteristics. All other electrical parameters remain equivalent.

Q: What is the difference between MC7808CTG and MC7808ECTBU? A: Both parts provide identical electrical performance (8V output, 1A current, 35V input maximum, 2V dropout voltage). The primary difference is product status: MC7808ECTBU is Obsolete while MC7808CTG is Active. The MC7808CTG is the recommended replacement for ongoing designs and procurement.

Q: Are all substitute parts available in the same TO-220-3 package? A: Yes. All listed substitute parts use TO-220-3 or compatible TO-220 package configuration, ensuring mechanical and thermal compatibility with existing PCB layouts and heatsinking arrangements.

Q: Can I use a 500mA part (MC78M08CTG) instead of the 1A MC7808ECTBU? A: Only if your application's maximum current requirement does not exceed 500mA. The MC78M08CTG provides equivalent voltage regulation and protection but cannot supply current beyond 500mA. Exceeding this limit will trigger short-circuit protection or cause voltage regulation failure.

Q: What is the significance of PSRR differences between substitute parts? A: PSRR (Power Supply Rejection Ratio) indicates the regulator's ability to reject input voltage ripple and noise. The MC7808ECTBU specifies 73dB at 120Hz. Substitute parts range from 56dB to 80dB. Higher PSRR values provide superior noise rejection. For noise-sensitive applications, select parts with PSRR equal to or greater than the original specification.

Q: Does the extended temperature range (-40°C ~ 125°C) of MC7808ABTG affect compatibility? A: No. Extended temperature range is a superset of the original specification (0°C ~ 125°C). Parts rated for -40°C ~ 125°C are fully compatible with applications designed for 0°C ~ 125°C operation. The extended range provides additional design flexibility for applications requiring lower temperature operation.

Q: Why does UA7808CKCS have a lower maximum input voltage (25V versus 35V)? A: The UA7808CKCS is specified for maximum 25V input. This part is suitable only for applications where input voltage remains below 25V. For applications requiring the full 35V input capability of the MC7808ECTBU, use alternative substitutes with 35V maximum input rating.

Q: Are all substitute parts RoHS3 compliant? A: Most substitute parts carry RoHS3 compliance certification. Verify specific compliance requirements for your application. The MC7808ECTBU itself is not explicitly marked as RoHS3 compliant in the provided specifications.

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