LM323AT Linear Voltage Regulator - Equivalent & Substitute Parts

Part Overview

The LM323AT is a linear voltage regulator IC manufactured by onsemi, designed to deliver a fixed positive 5V output at 3A current capacity in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The LM323AT provides over-current and over-temperature protection, operating across a 0°C to 125°C temperature range with a maximum input voltage of 20V.

Key Parameters

Parameter	Value
Output Voltage (Fixed)	5V
Output Current	3A
Input Voltage (Max)	20V
Output Configuration	Positive
Package Type	TO-220-3
Protection Features	Over Current, Over Temperature
Operating Temperature Range	0°C ~ 125°C
Quiescent Current	10 mA

Substitute Part Grouping Explanation

Substitution for the LM323AT is determined by the following critical parameters: fixed 5V output voltage, positive output configuration, TO-220-3 package compatibility, and through-hole mounting type. The primary substitutes are categorized as follows:

Parametric Equivalent: LT323AT#PBF (Analog Devices Inc.) matches the LM323AT across all critical electrical specifications, including 3A output current, 20V maximum input voltage, identical output voltage, and matching protection features. This part maintains full pin and functional compatibility.

Functional Substitute: L4941BV (STMicroelectronics) provides a 5V fixed output in TO-220-3 package with positive output configuration and through-hole mounting. However, this part operates at reduced output current (1A versus 3A) and lower maximum input voltage (16V versus 20V), making it suitable only for applications with lower current requirements.

Parameter Comparison

Parameter	LM323AT (onsemi)	LT323AT#PBF (Analog Devices)	L4941BV (STMicroelectronics)
Output Voltage	5V	5V	5V
Output Current	3A	3A	1A
Input Voltage (Max)	20V	20V	16V
Output Configuration	Positive	Positive	Positive
Package / Case	TO-220-3	TO-220-3	TO-220-3
Mounting Type	Through Hole	Through Hole	Through Hole
Protection Features	Over Current, Over Temperature	Over Current, Over Temperature	Over Temperature, Reverse Polarity, Short Circuit
Operating Temperature	0°C ~ 125°C	0°C ~ 125°C	-40°C ~ 150°C
Quiescent Current	10 mA	Not specified	8 mA
Product Status	Obsolete	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

LT323AT#PBF is the primary substitute for direct replacement of the LM323AT. This part is manufactured by Analog Devices Inc. and maintains active product status with ROHS3 compliance. Electrical specifications are identical across output voltage, output current, maximum input voltage, and protection features. Pin configuration and package type are fully compatible. This substitute requires no circuit modifications and provides equivalent performance characteristics.

L4941BV is a functional alternative only for applications where output current requirements do not exceed 1A. While this STMicroelectronics part shares the same 5V output voltage, TO-220-3 package, and positive output configuration, the reduced current rating (1A versus 3A) and lower maximum input voltage (16V versus 20V) restrict its use to lower-power applications. This part offers extended operating temperature range (-40°C to 150°C) and enhanced protection features including reverse polarity protection. ROHS3 compliance is provided.

Frequently Asked Questions (FAQ)

Q: Can L4941BV replace LM323AT in all applications? A: No. L4941BV is limited to 1A output current compared to LM323AT's 3A rating. Use L4941BV only in applications requiring 1A or less. Maximum input voltage is also reduced from 20V to 16V.

Q: Is LT323AT#PBF a direct replacement for LM323AT? A: Yes. LT323AT#PBF provides identical electrical specifications, pin configuration, and package type. No circuit modifications are required for substitution.

Q: What is the primary reason to substitute the LM323AT? A: The LM323AT is classified as obsolete. LT323AT#PBF and L4941BV are active products with current manufacturing and supply availability.

Q: Are all substitute parts RoHS compliant? A: LT323AT#PBF and L4941BV are both ROHS3 compliant. The original LM323AT is RoHS non-compliant.

Q: Do the substitute parts require different PCB layouts? A: No. All parts use identical TO-220-3 package and through-hole mounting, allowing direct PCB compatibility without layout modifications.

Q: What protection features differ between the substitutes? A: LM323AT and LT323AT#PBF provide over-current and over-temperature protection. L4941BV adds reverse polarity and short-circuit protection while maintaining over-temperature protection.

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