LM317TG Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The LM317TG is a positive adjustable linear voltage regulator IC manufactured by onsemi, rated for 1.5A output current in a TO-220-3 package. This device is actively produced and widely used in power management applications requiring adjustable output voltage from 1.2V to 37V with input voltages up to 40V. Finding equivalent and substitute parts is necessary for supply chain continuity, design flexibility, and sourcing optimization across multiple manufacturers including Texas Instruments, STMicroelectronics, and NTE Electronics.

Key Parameters

Parameter	LM317TG Specification
Manufacturer	onsemi
Package / Case	TO-220-3
Output Configuration	Positive
Output Type	Adjustable
Number of Regulators	1
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.2V
Voltage - Output (Max)	37V
Current - Output	1.5A
Current - Quiescent (Iq)	10 mA
PSRR	80dB ~ 65dB (120Hz)
Protection Features	Over Current, Over Temperature, Short Circuit
Operating Temperature	0°C ~ 125°C
Mounting Type	Through Hole
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the LM317TG are qualified based on the following critical parameters that determine functional interchangeability:

Electrical Parameters (Must Match or Exceed):

Output Configuration: Positive
Output Type: Adjustable
Number of Regulators: 1
Voltage - Input (Max): 40V minimum
Voltage - Output Range: 1.2V to 37V (or compatible subset)
Current - Output: 1.5A
Protection Features: Over Current, Over Temperature, Short Circuit

Physical Parameters (Must Match):

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

Compliance Parameters:

RoHS Status: ROHS3 Compliant

Substitute parts are grouped into two categories: Direct Substitutes (identical electrical and physical specifications) and Similar Substitutes (minor parameter variations that do not affect circuit functionality).

Parameter Comparison

Part Number	Manufacturer	Voltage - Input (Max)	Voltage - Output (Min)	Voltage - Output (Max)	Current - Output	Current - Quiescent (Iq)	PSRR	Operating Temperature	Product Status	Package
LM317TG	onsemi	40V	1.2V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
LM317KCS	Texas Instruments	40V	1.25V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
LM317KCSE3	Texas Instruments	40V	1.25V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	0°C ~ 125°C	Last Time Buy	TO-220-3
LM317T	NTE Electronics, Inc	37V	1.25V	37V	1.5A	—	64dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
LM317T-DG	STMicroelectronics	40V	1.2V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	0°C ~ 125°C	Active	TO-220-3
LM317AT/NOPB	Texas Instruments	40V	1.25V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	-40°C ~ 125°C	Active	TO-220-3
LM317KCT	Texas Instruments	40V	1.25V	37V	1.5A	10 mA	80dB ~ 65dB (120Hz)	0°C ~ 125°C	Obsolete	TO-220-3

Engineering Selection Recommendations

Direct Substitutes (Recommended for New Designs and Replacements):

LM317T-DG (STMicroelectronics) and LM317KCS (Texas Instruments) are the primary direct substitutes for LM317TG. Both devices match all critical electrical parameters, maintain identical package specifications, and carry Active product status with ROHS3 compliance. LM317T-DG offers the highest inventory availability (732,100 units) and identical minimum output voltage specification (1.2V) to the LM317TG.

Active Alternatives with Extended Temperature Range:

LM317AT/NOPB (Texas Instruments) provides an extended operating temperature range of -40°C to 125°C compared to the standard 0°C to 125°C range of LM317TG. This part is suitable for applications requiring wider temperature performance while maintaining all other electrical specifications and Active product status.

Avoid for New Designs:

LM317KCSE3 carries Last Time Buy status, indicating discontinued production. LM317KCT is marked Obsolete and should not be selected for new designs. LM317T (NTE Electronics) specifies a lower maximum input voltage (37V versus 40V) and reduced PSRR performance (64dB versus 80dB), making it less suitable for applications requiring the full 40V input specification.

Frequently Asked Questions (FAQ)

Q: Can LM317KCS replace LM317TG directly in existing circuits?

A: Yes. LM317KCS matches all critical electrical parameters including 40V maximum input voltage, 1.5A output current, and identical protection features. The minimum output voltage differs by 0.05V (1.25V versus 1.2V), which is negligible for most applications. Both use TO-220-3 packaging and are ROHS3 compliant.

Q: What is the difference between LM317T-DG and LM317TG?

A: LM317T-DG is manufactured by STMicroelectronics while LM317TG is from onsemi. Electrically, both devices are identical with 40V maximum input, 1.2V minimum output, 1.5A current rating, and matching PSRR specifications. Both are Active products in TO-220-3 packages. The primary difference is manufacturer and inventory availability.

Q: Why is LM317AT/NOPB listed as a similar substitute rather than direct?

A: LM317AT/NOPB extends the operating temperature range to -40°C, which is a performance enhancement rather than a limitation. All other electrical specifications match LM317TG. This part is suitable for applications requiring lower temperature operation but is not necessary for standard 0°C to 125°C applications.

Q: Is LM317KCSE3 suitable for new product designs?

A: No. LM317KCSE3 carries Last Time Buy status, indicating the manufacturer has announced end-of-life production. New designs should use LM317KCS, LM317T-DG, or LM317AT/NOPB, all of which maintain Active product status.

Q: What are the package considerations when substituting these parts?

A: All qualified substitutes use the TO-220-3 package with through-hole mounting. Pin configuration and thermal characteristics are identical, allowing direct PCB replacement without layout modifications. Verify that your application uses through-hole assembly; surface-mount variants are not included in this substitution list.

Q: Can LM317T from NTE Electronics be used as a substitute?

A: LM317T is functionally compatible for most applications but has two limitations: maximum input voltage is specified at 37V (versus 40V for LM317TG) and PSRR is 64dB (versus 80dB). Use this part only if your application operates below 37V input and does not require the higher noise rejection of the LM317TG.

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