LM317T Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The LM317T is a positive adjustable linear voltage regulator IC manufactured by onsemi, rated for 1.5A output current in a TO-220-3 package. This part is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The LM317T serves as a foundational adjustable regulator in power management applications where positive voltage regulation with user-selectable output levels is required.

Key Parameters

Parameter	Value
Manufacturer	onsemi
Part Number	LM317T
Product Status	Obsolete
Output Configuration	Positive
Output Type	Adjustable
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.2V
Voltage - Output (Max)	37V
Current - Output	1.5A
Current - Quiescent (Iq)	12 mA
PSRR (120Hz)	75dB ~ 60dB
Protection Features	Over Current, Over Temperature, Short Circuit
Operating Temperature	0°C ~ 125°C
Package / Case	TO-220-3
Mounting Type	Through Hole
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution for the LM317T is determined by the following critical parameters:

Electrical Compatibility Requirements:

Output Configuration: Positive
Output Type: Adjustable
Voltage - Input (Max): 40V minimum
Voltage - Output (Min/Fixed): 1.2V or lower
Voltage - Output (Max): 37V or higher
Current - Output: 1.5A or higher
Protection Features: Over Current, Over Temperature, Short Circuit

Mechanical Compatibility Requirements:

Package / Case: TO-220-3
Mounting Type: Through Hole

Substitute parts are grouped into two categories:

Direct Substitutes (Electrical and Mechanical Equivalence): Parts meeting all electrical parameters and identical package specifications. These include LM317TG (onsemi), LM317KCS (Texas Instruments), LM317KCSE3 (Texas Instruments), and LM317T-BP (Micro Commercial Co).

Similar Substitutes (Reduced Output Current): Parts meeting all electrical parameters except output current rating, which is reduced to 500mA. These include LM317MABTG, LM317MBTG, and LM317MTG (all onsemi). These are suitable only for applications requiring 500mA or less.

Cross-Manufacturer Alternatives: LM217T (STMicroelectronics) and LM317AT/NOPB (Texas Instruments) provide functional equivalence with extended operating temperature ranges and active product status.

Parameter Comparison

Part Number	Manufacturer	Product Status	Output Current	Voltage - Output (Min)	Voltage - Output (Max)	Quiescent Current (Iq)	PSRR (120Hz)	Operating Temperature	Package
LM317T	onsemi	Obsolete	1.5A	1.2V	37V	12 mA	75dB ~ 60dB	0°C ~ 125°C	TO-220-3
LM317TG	onsemi	Active	1.5A	1.2V	37V	10 mA	80dB ~ 65dB	0°C ~ 125°C	TO-220-3
LM317MABTG	onsemi	Active	500mA	1.2V	37V	10 mA	80dB ~ 65dB	-40°C ~ 125°C	TO-220-3
LM317MBTG	onsemi	Active	500mA	1.2V	37V	10 mA	80dB ~ 65dB	-40°C ~ 125°C	TO-220-3
LM317MTG	onsemi	Active	500mA	1.2V	37V	10 mA	80dB ~ 65dB	0°C ~ 125°C	TO-220-3
LM317KCS	Texas Instruments	Active	1.5A	1.25V	37V	10 mA	80dB ~ 65dB	0°C ~ 125°C	TO-220-3
LM317KCSE3	Texas Instruments	Last Time Buy	1.5A	1.25V	37V	10 mA	80dB ~ 65dB	0°C ~ 125°C	TO-220-3
LM317T-BP	Micro Commercial Co	Active	1.5A	1.25V	37V	100 µA	Not Specified	0°C ~ 125°C	TO-220-3
LM217T	STMicroelectronics	Active	1.5A	1.2V	37V	Not Specified	80dB ~ 65dB	-25°C ~ 150°C	TO-220-3
LM317AT/NOPB	Texas Instruments	Active	1.5A	1.25V	37V	10 mA	80dB ~ 65dB	-40°C ~ 125°C	TO-220-3
LM317KCT	Texas Instruments	Obsolete	1.5A	1.25V	37V	10 mA	80dB ~ 65dB	0°C ~ 125°C	TO-220-3

Engineering Selection Recommendations

For Direct Replacement (Active Product Status):

LM317TG (onsemi) is the primary direct replacement, offering identical electrical specifications with improved quiescent current performance (10 mA vs. 12 mA) and enhanced PSRR characteristics. This part is in active production status with tube packaging.

LM317KCS (Texas Instruments) provides full electrical equivalence with 1.5A output current and active product status. Minimum output voltage is specified at 1.25V versus 1.2V on the original part.

LM317AT/NOPB (Texas Instruments) offers the widest operating temperature range (-40°C to 125°C) with active product status and RoHS3 compliance, suitable for extended temperature applications.

For Cost-Optimized Applications (Reduced Current Requirement):

LM317MBTG and LM317MABTG (onsemi) are suitable for applications requiring 500mA or less output current. Both parts are in active production with improved quiescent current and PSRR performance. LM317MABTG extends the operating temperature range to -40°C to 125°C.

For Extended Temperature Range:

LM217T (STMicroelectronics) supports operating temperatures from -25°C to 150°C, providing the widest thermal envelope among available substitutes. This part maintains 1.5A output current and is in active production status.

Compliance Considerations:

All recommended active substitutes carry RoHS3 compliance certification. The original LM317T and LM317KCT are classified as obsolete; new designs should transition to active alternatives. LM317KCSE3 is designated Last Time Buy and should not be selected for new production.

Frequently Asked Questions (FAQ)

Q: Can LM317MBTG or LM317MABTG replace LM317T in all applications?

A: These parts are suitable only for applications requiring 500mA or less output current. The LM317T is rated for 1.5A. If your application requires the full 1.5A output capability, use LM317TG, LM317KCS, or LM317AT/NOPB instead.

Q: What is the difference between LM317TG and LM317T?

A: LM317TG is the active production equivalent of the obsolete LM317T. Both deliver 1.5A output current in TO-220-3 packages. LM317TG features lower quiescent current (10 mA vs. 12 mA) and improved PSRR performance (80dB ~ 65dB vs. 75dB ~ 60dB).

Q: Is LM217T a direct substitute for LM317T?

A: LM217T is functionally equivalent for positive adjustable voltage regulation with 1.5A output. The primary difference is the extended operating temperature range (-25°C to 150°C vs. 0°C to 125°C). Both use TO-220-3 packages and support identical voltage specifications.

Q: Why should I avoid LM317KCT and LM317KCSE3?

A: LM317KCT is classified as obsolete. LM317KCSE3 is designated Last Time Buy, indicating limited future availability. For new designs, select from active product status alternatives such as LM317TG, LM317KCS, or LM317AT/NOPB.

Q: What is the minimum output voltage difference between LM317T and Texas Instruments alternatives?

A: LM317T specifies 1.2V minimum output voltage. Texas Instruments parts (LM317KCS, LM317KCSE3, LM317AT/NOPB) specify 1.25V minimum output voltage. This 50mV difference is negligible for most applications but should be verified for precision voltage regulation circuits.

Q: Are all substitute parts RoHS3 compliant?

A: All active production substitutes listed carry RoHS3 compliance certification. The original LM317T does not specify RoHS status. Verify compliance requirements for your specific application and supply chain.

Q: Can I use LM317T-BP as a direct replacement?

A: LM317T-BP is electrically compatible with 1.5A output current and TO-220-3 package. However, it specifies significantly lower quiescent current (100 µA vs. 12 mA) and does not provide PSRR specifications. Verify performance characteristics against your circuit requirements before substitution.

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