LM317KCSE3 Equivalent & Substitute Parts

Part Overview

The LM317KCSE3 is a linear voltage regulator IC from Texas Instruments designed for positive adjustable output applications. It delivers 1.5A output current in a TO-220-3 through-hole package and operates across an input voltage range of up to 40V with adjustable output from 1.25V to 37V. The device includes integrated protection features for overcurrent, overtemperature, and short circuit conditions.

The LM317KCSE3 is classified as Last Time Buy, indicating limited availability. Identifying equivalent and substitute parts ensures design continuity and supply chain flexibility for applications requiring positive adjustable linear regulation.

Key Parameters

Parameter	Value
Manufacturer	Texas Instruments
Package / Case	TO-220-3
Mounting Type	Through Hole
Output Configuration	Positive
Output Type	Adjustable
Voltage - Input (Max)	40V
Voltage - Output (Min/Fixed)	1.25V
Voltage - Output (Max)	37V
Current - Output	1.5A
Current - Quiescent (Iq)	10 mA
PSRR	80dB ~ 65dB (120Hz)
Operating Temperature	0°C ~ 125°C
Protection Features	Over Current, Over Temperature, Short Circuit
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the LM317KCSE3 is determined by the following critical parameters:

Package / Case: TO-220-3 (through-hole mounting required for direct PCB compatibility)
Output Current: 1.5A (minimum requirement for load support)
Voltage Range: Input maximum 40V, output adjustable 1.25V to 37V
Protection Features: Overcurrent, overtemperature, and short circuit protection
Compliance: ROHS3 compliance and REACH unaffected status

Parts are grouped into three categories:

Direct Equivalents (TO-220-3, 1.5A): Full electrical and mechanical compatibility with identical package and current rating
Parametric Equivalents (TO-220-3, reduced current): Same package and voltage range but lower output current (500mA), suitable only for reduced-load applications
Package Variants (Surface Mount): Identical electrical specifications but different mounting technology (DDPAK/TO-263)

Parameter Comparison

Part Number	Manufacturer	Package	Mounting	Output Current	Input Voltage (Max)	Output Voltage Range	Operating Temp	Product Status
LM317KCSE3	Texas Instruments	TO-220-3	Through Hole	1.5A	40V	1.25V - 37V	0°C ~ 125°C	Last Time Buy
LM317T/NOPB	Texas Instruments	TO-220-3	Through Hole	1.5A	37V	1.25V - 37V	0°C ~ 125°C	Active
LM317AT/NOPB	Texas Instruments	TO-220-3	Through Hole	1.5A	40V	1.25V - 37V	-40°C ~ 125°C	Active
LM317T	NTE Electronics, Inc	TO-220-3	Through Hole	1.5A	37V	1.25V - 37V	0°C ~ 125°C	Active
LM317T-BP	Micro Commercial Co	TO-220-3	Through Hole	1.5A	40V	1.25V - 37V	0°C ~ 125°C	Active
LM317KTTR	Texas Instruments	TO-263 (DDPAK-3)	Surface Mount	1.5A	40V	1.25V - 37V	0°C ~ 125°C	Active
LM317MBTG	onsemi	TO-220-3	Through Hole	500mA	40V	1.2V - 37V	-40°C ~ 125°C	Active
LM317MABTG	onsemi	TO-220-3	Through Hole	500mA	40V	1.2V - 37V	-40°C ~ 125°C	Active
LM317MTG	onsemi	TO-220-3	Through Hole	500mA	40V	1.2V - 37V	0°C ~ 125°C	Active
LM317KCT	Texas Instruments	TO-220-3	Through Hole	1.5A	40V	1.25V - 37V	0°C ~ 125°C	Obsolete

Engineering Selection Recommendations

Direct Substitutes (Recommended for 1.5A Applications)

LM317AT/NOPB and LM317T/NOPB from Texas Instruments are the primary active alternatives. LM317AT/NOPB offers extended operating temperature range (-40°C to 125°C) compared to the LM317KCSE3 (0°C to 125°C), providing broader environmental compatibility. Both maintain the 40V input maximum and 1.5A output current specification. LM317T/NOPB operates at 37V maximum input, which is acceptable for most applications but represents a reduced margin compared to the original 40V specification.

LM317T from NTE Electronics and LM317T-BP from Micro Commercial Co provide functionally equivalent alternatives in TO-220-3 packaging with 1.5A output capability. These options ensure supply chain diversity while maintaining electrical compatibility.

Surface Mount Alternative

LM317KTTR from Texas Instruments provides identical electrical specifications in TO-263 (DDPAK-3) surface mount packaging. This option is suitable only for designs that support surface mount assembly and does not require PCB layout modification for through-hole mounting.

Reduced Current Alternatives (500mA)

LM317MBTG, LM317MABTG, and LM317MTG from onsemi deliver 500mA output current in TO-220-3 through-hole packaging. These parts are suitable only for applications with maximum load current of 500mA or less. All three variants maintain 40V input maximum and adjustable output voltage range. LM317MBTG and LM317MABTG support -40°C to 125°C operating temperature, while LM317MTG operates from 0°C to 125°C.

Obsolete Part

LM317KCT is classified as obsolete and should not be selected for new designs despite parametric equivalence to the LM317KCSE3.

Frequently Asked Questions (FAQ)

Q: Can LM317T/NOPB replace LM317KCSE3 directly?

A: LM317T/NOPB is electrically compatible in TO-220-3 packaging with 1.5A output current and adjustable voltage range. The primary difference is maximum input voltage: LM317T/NOPB operates at 37V maximum versus 40V for LM317KCSE3. For applications with input voltage below 37V, direct substitution is valid. For designs requiring the full 40V input margin, LM317AT/NOPB or LM317T-BP are preferred.

Q: What is the difference between LM317MBTG and LM317MABTG?

A: Both parts are from onsemi with identical electrical specifications: 500mA output current, 40V input maximum, and adjustable 1.2V to 37V output. The primary difference is temperature range: LM317MABTG supports -40°C to 125°C while LM317MBTG supports -40°C to 125°C. Both are suitable only for applications with maximum load current of 500mA.

Q: Can I use LM317KTTR as a substitute?

A: LM317KTTR provides identical electrical specifications but uses TO-263 (DDPAK-3) surface mount packaging instead of through-hole TO-220-3. Substitution requires PCB redesign to accommodate surface mount assembly. This option is valid only if your manufacturing process supports surface mount technology.

Q: Why are onsemi parts rated for 500mA instead of 1.5A?

A: LM317MBTG, LM317MABTG, and LM317MTG are lower-current variants of the LM317 family. These parts are not suitable for applications requiring 1.5A output. Use only if your design maximum load current is 500mA or less.

Q: Is LM317KCT still available?

A: LM317KCT is classified as obsolete. Although 2,600 units remain in inventory, this part should not be selected for new designs. Active alternatives such as LM317AT/NOPB or LM317T/NOPB are recommended.

Q: What compliance certifications apply to substitute parts?

A: All recommended substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the environmental and regulatory requirements of the LM317KCSE3.

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