AN78L12 Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The AN78L12 is a linear voltage regulator IC manufactured by Panasonic Electronic Components, designed to provide a fixed positive 12V output at 100mA. This device features integrated over-current and over-temperature protection in a 3-SSIP package (TO-92-3 form factor). The AN78L12 is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain identical electrical specifications and mechanical compatibility to ensure direct replacement capability.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	12V
Output Current	100mA
Input Voltage (Max)	35V
Output Configuration	Positive
Output Type	Fixed
Number of Regulators	1
Package / Case	TO-226-3, TO-92-3 (TO-226AA)
Mounting Type	Through Hole
Protection Features	Over Current, Over Temperature
Operating Temperature Range	0°C ~ 125°C

Substitute Part Grouping Explanation

Substitute parts for the AN78L12 are qualified based on the following critical parameters:

Fixed 12V output voltage
100mA output current capability
35V maximum input voltage rating
Positive output configuration
Single regulator topology
TO-92-3 package compatibility (through-hole mounting)
Over-current and over-temperature protection

Parts meeting these specifications are functionally equivalent and mechanially compatible. Variations in quiescent current (Iq), PSRR (Power Supply Rejection Ratio), and operating temperature range do not affect substitution eligibility when the core electrical and mechanical parameters align.

Parameter Comparison

Part Number	Manufacturer	Output Voltage	Output Current	Input Voltage (Max)	Package	Iq (mA)	PSRR (dB @ 120Hz)	Operating Temp	Product Status
AN78L12	Panasonic	12V	100mA	35V	TO-92-3	4.6	50	0°C ~ 125°C	Obsolete
L78L12ABZ	STMicroelectronics	12V	100mA	35V	TO-92-3	6	42	-40°C ~ 125°C	Active
L78L12ABZ-AP	STMicroelectronics	12V	100mA	35V	TO-92-3	6	42	-40°C ~ 125°C	Active
L78L12ACZ	STMicroelectronics	12V	100mA	35V	TO-92-3	6	42	0°C ~ 125°C	Active
LM78L12ACZ/NOPB	Texas Instruments	12V	100mA	35V	TO-92-3	3	54	0°C ~ 125°C	Active
MC78L12ABPG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	-40°C ~ 125°C	Active
MC78L12ABPRPG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	-40°C ~ 125°C	Active
MC78L12ACPG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	0°C ~ 125°C	Active
MC78L12ACPRAG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	0°C ~ 125°C	Active
MC78L12ACPREG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	0°C ~ 125°C	Active
MC78L12ACPRMG	onsemi	12V	100mA	35V	TO-92-3	6.5	42	0°C ~ 125°C	Active

Engineering Selection Recommendations

All listed substitute parts are functionally and mechanically equivalent to the AN78L12. Selection should be based on the following criteria:

Product Status: All substitute parts carry Active product status, ensuring long-term availability and manufacturing support compared to the obsolete AN78L12.

Compliance & Certifications: STMicroelectronics L78L12 series, Texas Instruments LM78L12ACZ/NOPB, and onsemi MC78L12 series all maintain ROHS3 compliance and REACH unaffected status where applicable, meeting modern regulatory requirements.

Operating Temperature Range: For applications requiring extended low-temperature operation (-40°C), select L78L12ABZ, L78L12ABZ-AP, MC78L12ABPG, or MC78L12ABPRPG. For standard industrial range (0°C ~ 125°C), L78L12ACZ, LM78L12ACZ/NOPB, MC78L12ACPG, MC78L12ACPRAG, MC78L12ACPREG, and MC78L12ACPRMG are suitable.

Packaging Variants: Cut Tape (CT) packaging is available for L78L12ABZ-AP, MC78L12ABPRPG, MC78L12ACPRAG, MC78L12ACPREG, and MC78L12ACPRMG. Bulk packaging is available for L78L12ABZ, L78L12ACZ, LM78L12ACZ/NOPB, MC78L12ABPG, and MC78L12ACPG.

Inventory Availability: onsemi MC78L12ABPG offers the highest inventory level (689,288 pcs), followed by STMicroelectronics L78L12ACZ (17,300 pcs) and L78L12ABZ-AP (8,555 pcs).

Frequently Asked Questions (FAQ)

Q: Can I directly replace AN78L12 with any of the listed substitute parts?

A: Yes. All listed parts meet the core electrical and mechanical specifications: 12V fixed output, 100mA current capability, 35V input rating, and TO-92-3 package compatibility. Direct pin-for-pin replacement is supported.

Q: What is the difference between L78L12ABZ and L78L12ACZ?

A: Both are STMicroelectronics parts with identical electrical performance. The primary difference is operating temperature range: L78L12ABZ operates from -40°C to 125°C, while L78L12ACZ operates from 0°C to 125°C. Select based on your application's minimum operating temperature requirement.

Q: Why do some parts have higher quiescent current (Iq)?

A: Quiescent current variation (3 mA to 6.5 mA) reflects different semiconductor process technologies across manufacturers. This parameter does not affect substitution eligibility and has minimal impact on most applications unless ultra-low standby power is critical.

Q: What does the suffix in part numbers like "ABZ-AP" or "ACPREG" indicate?

A: Suffixes denote packaging and lead configuration variants. "-AP" indicates formed leads in cut tape packaging. "ACPREG" and similar designations specify cut tape packaging with specific lead treatments. Consult manufacturer datasheets for exact mechanical specifications.

Q: Are all substitute parts RoHS compliant?

A: Yes. All active substitute parts listed carry ROHS3 compliance certification, meeting current environmental and regulatory standards.

Q: Which substitute part offers the best PSRR performance?

A: LM78L12ACZ/NOPB from Texas Instruments provides the highest PSRR at 54dB (120Hz), compared to 42dB for most other substitutes and 50dB for the original AN78L12.

Q: Can I use parts with -40°C minimum operating temperature in applications rated for 0°C minimum?

A: Yes. Parts rated for -40°C to 125°C are fully compatible with applications requiring 0°C to 125°C operation, as they exceed the minimum temperature requirement.

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