LM317KC Linear Voltage Regulator Equivalent & Substitute Parts

Part Overview

The LM317KC is a positive adjustable linear voltage regulator IC manufactured by Texas Instruments, rated for 1.5A output current in a TO-220-3 package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The LM317KC provides adjustable output voltage regulation from 1.25V to 37V with integrated protection features including over-current, over-temperature, and short-circuit protection.

Substiute Parts

LM317KC

Texas InstrumentsIn Stock: 18428LM317KC Datasheet

Current PartRFQ

LM317T/NOPB

Texas InstrumentsIn Stock: 188472LM317T/NOPB Datasheet

DirectRFQ

LM317T

NTE Electronics, IncIn Stock: 89059LM317T Datasheet

DirectRFQ

LM317T-BP

Micro Commercial CoIn Stock: 956LM317T-BP Datasheet

DirectRFQ

LM317TG

onsemiIn Stock: 2439LM317TG Datasheet

DirectRFQ

LM317KCT

Texas InstrumentsIn Stock: 2619LM317KCT Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the LM317KC are classified based on electrical and mechanical compatibility within the following criteria:

Direct Manufacturer Substitutes maintain identical or equivalent electrical specifications across all critical parameters: output voltage range (1.25V to 37V), output current (1.5A), quiescent current (10 mA), protection features (over-current, over-temperature, short-circuit), operating temperature range (0°C to 125°C), and TO-220-3 package configuration. These parts are functionally interchangeable in circuit applications.

Parametric Equivalents meet the same electrical performance requirements but may differ in product status, RoHS compliance, or specific certifications. These parts satisfy the core functional requirements for voltage regulation and current delivery.

Key parameters determining substitution eligibility:

• Output voltage range: 1.25V minimum to 37V maximum
• Output current rating: 1.5A
• Package type: TO-220-3 or compatible TO-220 variants
• Protection features: Over-current, over-temperature, short-circuit
• Operating temperature: 0°C to 125°C

Parameter Comparison

Engineering Selection Recommendations

For Active Product Designs: LM317T/NOPB (Texas Instruments) is the primary recommended substitute. This part maintains Texas Instruments manufacturing continuity, carries active product status, and achieves ROHS3 compliance. The maximum input voltage specification of 37V accommodates most standard applications within the LM317KC's 40V rating.

For Maximum Input Voltage Requirement (40V): LM317TG (onsemi) or LM317T-BP (Micro Commercial Co) are suitable alternatives. Both support the full 40V input specification matching the original LM317KC. LM317TG provides ROHS3 compliance and active product status. LM317T-BP offers active status but lacks specified RoHS certification.

For Legacy System Maintenance: LM317KCT (Texas Instruments) provides parametric equivalence with identical electrical specifications to the LM317KC, including 40V input rating and PSRR performance. However, this part is classified as obsolete and should be considered only when design constraints prevent adoption of active alternatives.

Compliance Considerations: Designs requiring RoHS3 compliance should prioritize LM317T/NOPB, LM317T, or LM317TG. The original LM317KC is RoHS non-compliant and LM317KCT, while ROHS3 compliant, carries obsolete status.

Frequently Asked Questions (FAQ)

Q: Can LM317T/NOPB directly replace LM317KC in existing designs?

A: Yes. LM317T/NOPB maintains electrical compatibility across all critical parameters: 1.5A output current, 1.25V to 37V output voltage range, TO-220-3 package, and identical protection features. The maximum input voltage specification is 37V versus the LM317KC's 40V; this difference is acceptable for applications operating below 37V input.

Q: What is the difference between LM317T and LM317T/NOPB?

A: LM317T/NOPB is the lead-free version (NOPB = No Organic Bromide) manufactured by Texas Instruments with ROHS3 compliance. Both parts share identical electrical specifications and TO-220-3 packaging. LM317T/NOPB is the preferred specification for new designs.

Q: Why does LM317TG specify 1.2V minimum output voltage instead of 1.25V?

A: LM317TG (onsemi) achieves a lower minimum output voltage of 1.2V while maintaining all other electrical parameters. This represents an enhanced specification that provides greater design flexibility for low-voltage applications. The part remains fully compatible with designs requiring 1.25V minimum output.

Q: Is the TO-220-3 package identical across all substitute parts?

A: All listed substitutes use TO-220-3 or compatible TO-220 package variants. LM317T-BP specifies TO-220AB as the supplier device package, which is mechanically and electrically compatible with standard TO-220-3 configurations. Pin assignments and thermal characteristics remain consistent across all variants.

Q: Can I use LM317KCT as a direct replacement for LM317KC?

A: LM317KCT provides parametric equivalence with identical electrical specifications and 40V input rating. However, both parts carry obsolete product status. For new procurement, active alternatives such as LM317T/NOPB or LM317TG are recommended to ensure long-term supply chain availability.

Q: What are the quiescent current differences among substitutes?

A: Most substitutes specify 10 mA quiescent current matching the LM317KC. LM317T-BP specifies 100 µA, representing significantly lower quiescent current consumption. This difference may be advantageous in battery-powered or low-power standby applications. NTE Electronics LM317T does not provide quiescent current specification in available documentation.