LM78L12ACZX Equivalent & Substitute Parts

Part Overview

The LM78L12ACZX is a linear voltage regulator IC manufactured by onsemi, designed to provide a fixed positive 12V output at 100mA. This device features integrated over-temperature and short-circuit protection, operating across a -40°C to 125°C temperature range with a maximum input voltage of 35V. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	12V
Output Current	100mA
Input Voltage (Max)	35V
Quiescent Current	6 mA
PSRR @ 120Hz	65dB
Operating Temperature Range	-40°C to 125°C
Package	TO-92-3 (TO-226AA)
Protection Features	Over Temperature, Short Circuit

Substitute Part Grouping Explanation

Substitution for the LM78L12ACZX is determined by the following critical parameters:

Fixed output voltage of 12V
Output current capability of 100mA minimum
Input voltage tolerance up to 35V
TO-92-3 package compatibility
Through-hole mounting configuration
Operating temperature range support

Substitute parts are grouped into two categories:

Category 1: onsemi MC78L12 Series (Active Status) These parts maintain identical electrical specifications with the LM78L12ACZX while offering active product status. Variants include MC78L12ABPRPG, MC78L12ACPRAG, MC78L12ACPREG, MC78L12ACPRMG, and MC78L12ACPRPG, differentiated by packaging and temperature range options.

Category 2: Cross-Manufacturer Alternatives Texas Instruments UA78L12ACLPR and STMicroelectronics L78L12 series (L78L12ABZ-AP, L78L12ACZ-AP, L78L12ACZ-TR) provide functional equivalence with identical output specifications and package compatibility.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Quiescent Current (mA)	PSRR @ 120Hz	Operating Temp Range	Product Status	Package
LM78L12ACZX	onsemi	12V	100mA	35V	6	65dB	-40°C to 125°C	Obsolete	TO-92-3
MC78L12ABPRPG	onsemi	12V	100mA	35V	6.5	42dB	-40°C to 125°C	Active	TO-92-3
MC78L12ACPRAG	onsemi	12V	100mA	35V	6.5	42dB	0°C to 125°C	Active	TO-92-3
MC78L12ACPREG	onsemi	12V	100mA	35V	6.5	42dB	0°C to 125°C	Active	TO-92-3
MC78L12ACPRMG	onsemi	12V	100mA	35V	6.5	42dB	0°C to 125°C	Active	TO-92-3
MC78L12ACPRPG	onsemi	12V	100mA	35V	6.5	42dB	0°C to 125°C	Active	TO-92-3
UA78L12ACLPR	Texas Instruments	12V	100mA	27V	Not specified	42dB	0°C to 125°C	Last Time Buy	TO-92-3
L78L12ABZ-AP	STMicroelectronics	12V	100mA	35V	6	42dB	-40°C to 125°C	Active	TO-92-3
L78L12ACZ-AP	STMicroelectronics	12V	100mA	35V	6	42dB	0°C to 125°C	Active	TO-92-3
L78L12ACZ-TR	STMicroelectronics	12V	100mA	35V	6	42dB	0°C to 125°C	Active	TO-92-3
LM78L12ACZ/LFT7	Texas Instruments	12V	100mA	35V	3	54dB	0°C to 125°C	Active	TO-92-3

Engineering Selection Recommendations

Primary Substitutes (Recommended for New Designs)

The onsemi MC78L12ABPRPG is the preferred substitute, maintaining the extended temperature range (-40°C to 125°C) of the original LM78L12ACZX while offering active product status and current availability. This part is electrically compatible with identical output specifications and package configuration.

For applications requiring extended temperature operation with improved quiescent current performance, the STMicroelectronics L78L12ABZ-AP provides equivalent functionality with active status and ROHS3 compliance.

Secondary Substitutes (Temperature-Constrained Applications)

The onsemi MC78L12ACPRAG, MC78L12ACPREG, MC78L12ACPRMG, and MC78L12ACPRPG variants are suitable for applications operating within the 0°C to 125°C range. These parts offer active product status with high inventory availability.

Alternative Cross-Manufacturer Options

The Texas Instruments LM78L12ACZ/LFT7 provides superior PSRR performance (54dB versus 65dB of the original) and reduced quiescent current (3mA), making it suitable for noise-sensitive applications. However, this part operates within the 0°C to 125°C temperature range.

The Texas Instruments UA78L12ACLPR carries Last Time Buy status with maximum input voltage limited to 27V, making it suitable only for applications with input voltages below 27V.

Frequently Asked Questions (FAQ)

Q: Can MC78L12ACPRAG replace LM78L12ACZX in all applications?

A: MC78L12ACPRAG is electrically compatible for output voltage and current specifications. However, it operates within 0°C to 125°C, whereas the original operates from -40°C to 125°C. Verify your application's minimum operating temperature requirement before substitution.

Q: What is the difference between MC78L12ABPRPG and MC78L12ACPRAG?

A: Both parts are functionally equivalent with identical electrical specifications. MC78L12ABPRPG supports -40°C to 125°C operation, while MC78L12ACPRAG operates from 0°C to 125°C. Select based on your minimum operating temperature requirement.

Q: Is the Texas Instruments UA78L12ACLPR a direct replacement?

A: UA78L12ACLPR provides identical output voltage and current specifications in the same TO-92-3 package. However, its maximum input voltage is 27V compared to 35V for the LM78L12ACZX. Verify your input voltage does not exceed 27V before using this substitute.

Q: Why does LM78L12ACZ/LFT7 show lower quiescent current?

A: LM78L12ACZ/LFT7 is a newer Texas Instruments design with improved quiescent current performance (3mA versus 6mA). This represents a design improvement and is compatible for direct substitution in applications operating within 0°C to 125°C.

Q: Are all substitute parts ROHS3 compliant?

A: The onsemi MC78L12 series, STMicroelectronics L78L12 series, and Texas Instruments LM78L12ACZ/LFT7 are ROHS3 compliant. The original LM78L12ACZX and Texas Instruments UA78L12ACLPR do not specify ROHS3 compliance in their product documentation.

Q: Can I use these parts interchangeably in existing designs?

A: All substitute parts maintain identical TO-92-3 package pinout and electrical output specifications (12V, 100mA). Verify operating temperature range and input voltage specifications match your application requirements before substitution.

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