K1500S Equivalent & Substitute Parts Reference

Part Overview

The K1500S is a SIDAC (Silicon Diode for Alternating Current) thyristor manufactured by Littelfuse Inc., rated for 140–170V breakover voltage with 1A peak output current in a DO-214AA/SMB surface mount package. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility across breakover voltage, current ratings, and thermal operating range while accommodating packaging and supply chain constraints.

Substiute Parts

K1500S

Littelfuse Inc.In Stock: 3622K1500S Datasheet

Current PartRFQ

K1500SRP

Littelfuse Inc.In Stock: 3997K1500SRP Datasheet

DirectRFQ

SMP100LC-90

STMicroelectronicsIn Stock: 1946SMP100LC-90 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the K1500S is determined by the following critical parameters:

• Voltage - Breakover: Must fall within or encompass the 140–170V range to ensure triggering occurs at the intended circuit voltage threshold
• Current - Hold (Ih): Must not exceed 150 mA to maintain circuit stability and prevent unintended latching
• Package / Case: Must be DO-214AA/SMB to ensure mechanical and electrical compatibility with existing PCB layouts
• Operating Temperature Range: Must support −40°C to +125°C to match thermal design requirements
• RoHS Compliance: Must maintain ROHS3 compliance for regulatory and supply chain consistency

Two substitute parts are identified:

1. K1500SRP (Littelfuse Inc.): Direct electrical and mechanical equivalent with identical specifications; differs only in packaging format (Tape & Reel vs. bulk) and product status (Active vs. Obsolete)
2. SMP100LC-90 (STMicroelectronics): TVS thyristor with different electrical characteristics; included as manufacturer-recommended alternative but with significant parameter deviations requiring circuit-level evaluation

Parameter Comparison

Engineering Selection Recommendations

K1500SRP is the primary substitute for K1500S. Both parts are manufactured by Littelfuse Inc. with identical electrical specifications, thermal range, and package form factor. K1500SRP is currently in active production status with 3,900 units in stock, providing supply continuity. The only functional difference is packaging format (Tape & Reel vs. bulk), which does not affect electrical performance. ROHS3 compliance is maintained across both parts.

SMP100LC-90 is listed as a manufacturer-recommended alternative but exhibits significant electrical deviations. The breakover voltage is 125V (below the K1500S minimum of 140V), and peak pulse current is rated at 400A (8/20µs), substantially exceeding the K1500S 1A specification. This part is classified as a TVS thyristor rather than a SIDAC, indicating different functional behavior. SMP100LC-90 is suitable only for applications where lower breakover voltage and higher transient current handling are acceptable design modifications. Direct substitution without circuit re-evaluation is not recommended.

Frequently Asked Questions (FAQ)

Q: Can K1500SRP be used as a direct replacement for K1500S?

A: Yes. K1500SRP is electrically and mechanically identical to K1500S. Both parts share the same breakover voltage (140–170V), hold current (150 mA max), peak output current (1 A), operating temperature range (−40°C to +125°C), and DO-214AA/SMB package. The only difference is packaging format (Tape & Reel vs. bulk) and active production status. No circuit modifications are required.

Q: What are the key differences between K1500S and SMP100LC-90?

A: SMP100LC-90 differs in three critical areas: (1) breakover voltage is 125V versus K1500S 140–170V, (2) peak pulse current is 400A (8/20µs) versus K1500S 1A, and (3) device classification is TVS thyristor versus SIDAC. These differences indicate fundamentally different circuit behavior. SMP100LC-90 is designed for transient suppression with high current handling, not for the voltage-triggered switching function of a SIDAC.

Q: Is SMP100LC-90 a suitable substitute for K1500S?

A: SMP100LC-90 is not a direct substitute. While both parts share the same package and hold current specification, the lower breakover voltage and significantly higher peak pulse current rating indicate different functional intent. Use of SMP100LC-90 requires circuit-level analysis to confirm compatibility with the intended application voltage and current profile.

Q: Does packaging format affect electrical performance?

A: No. Tape & Reel (TR) and bulk packaging formats contain identical components. The difference is in delivery and handling format only. K1500SRP in Tape & Reel format is electrically equivalent to K1500S in bulk format.

Q: Are both substitute parts RoHS compliant?

A: Yes. K1500SRP and SMP100LC-90 are both ROHS3 compliant, maintaining regulatory consistency with the obsolete K1500S.