LM338T Linear Voltage Regulator IC Equivalent & Substitute Parts

Part Overview

The LM338T is a positive adjustable linear voltage regulator manufactured by Texas Instruments, designed for applications requiring 5A output current with adjustable voltage output from 1.24V to 32V. The device is packaged in TO-220-3 and operates across a 0°C to 125°C temperature range. The LM338T carries a Last Time Buy product status, indicating limited availability. Finding equivalent and substitute parts is necessary to ensure design continuity and maintain supply chain flexibility for new production runs and long-term support.

Substiute Parts

LM338T

Texas InstrumentsIn Stock: 2008LM338T Datasheet

Current PartRFQ

LM338T/NOPB

Texas InstrumentsIn Stock: 27959LM338T/NOPB Datasheet

DirectRFQ

LM317BTG

onsemiIn Stock: 100204LM317BTG Datasheet

MFR RecommendedRFQ

LM317TG

onsemiIn Stock: 2439LM317TG Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LM338T is determined by the following critical parameters:

Primary Substitution Criteria:

• Output Configuration: Positive
• Output Type: Adjustable
• Package / Case: TO-220-3
• Voltage - Input (Max): 40V
• Voltage - Output (Min/Fixed): ≥ 1.24V
• Voltage - Output (Max): ≥ 32V
• Current - Output: ≥ 5A
• Mounting Type: Through Hole
• RoHS Status: ROHS3 Compliant

Direct Equivalent: LM338T/NOPB is a direct equivalent manufactured by Texas Instruments with identical electrical specifications and packaging. The only difference is the packaging format (Tube vs. standard packaging) and product status (Active vs. Last Time Buy).

Functional Substitutes: LM317BTG and LM317TG are manufactured by onsemi and represent functional substitutes. These devices share the same TO-220-3 package, positive adjustable output configuration, and 40V maximum input voltage. However, they differ in current output capacity (1.5A vs. 5A) and maximum output voltage (37V vs. 32V). These substitutes are suitable only for applications where the reduced current rating and output voltage range are acceptable.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement: LM338T/NOPB is the recommended direct substitute. It maintains identical electrical specifications and package configuration while offering Active product status and higher inventory availability (27,900 units in stock vs. 1,920 units for LM338T). This part is suitable for all applications currently using LM338T without circuit modification.

For Functional Substitution: LM317BTG and LM317TG are suitable only when application requirements permit reduced output current (1.5A maximum) and can accommodate the higher maximum output voltage (37V). Both devices are manufactured by onsemi with Active product status and ROHS3 compliance. LM317BTG supports extended operating temperature range (-40°C to 125°C), while LM317TG matches the LM338T operating range (0°C to 125°C). Both include Over Current protection in addition to Over Temperature and Short Circuit protection.

All substitute parts maintain TO-220-3 packaging, positive adjustable output configuration, and 40V maximum input voltage rating, ensuring mechanical and electrical compatibility within the specified parameter constraints.

Frequently Asked Questions (FAQ)

Q: Can LM338T/NOPB be used as a direct replacement for LM338T? A: Yes. LM338T/NOPB is a direct equivalent with identical electrical specifications, output current rating (5A), voltage range (1.24V to 32V), and TO-220-3 package. The only differences are packaging format (Tube) and product status (Active vs. Last Time Buy). No circuit modifications are required.

Q: What are the key differences between LM338T and LM317BTG? A: The primary differences are output current capacity (5A vs. 1.5A) and maximum output voltage (32V vs. 37V). LM317BTG also includes Over Current protection and supports an extended operating temperature range (-40°C to 125°C). LM317BTG is suitable only for applications where the reduced current rating is acceptable.

Q: Can LM317TG replace LM338T in all applications? A: No. LM317TG has a maximum output current of 1.5A compared to LM338T's 5A rating. It is suitable only for low-current applications. The operating temperature range (0°C to 125°C) matches LM338T, but the reduced current capacity makes it unsuitable for high-current designs.

Q: Are all substitute parts RoHS3 compliant? A: Yes. LM338T/NOPB, LM317BTG, and LM317TG are all ROHS3 compliant, meeting environmental and regulatory requirements for new designs.

Q: What is the difference in PSRR between LM338T and the LM317 series substitutes? A: LM338T has a PSRR of 75dB ~ 60dB (120Hz), while LM317BTG and LM317TG have a PSRR of 80dB ~ 65dB (120Hz). The LM317 series offers slightly superior power supply rejection ratio performance.

Q: Which substitute has the best inventory availability? A: LM338T/NOPB has the highest inventory with 27,900 units in stock, compared to 2,344 units for LM317TG and 100,099 units for LM317BTG. For immediate availability of a direct equivalent, LM338T/NOPB is the optimal choice.

Q: Do all parts use the same TO-220-3 package? A: Yes. LM338T, LM338T/NOPB, LM317BTG, and LM317TG all use TO-220-3 packaging with identical pin configuration and mechanical dimensions, ensuring direct PCB compatibility.