SCT840B Equivalent & Substitute Parts Reference

Part Overview

The SCT840B is a standard recovery silicon-controlled rectifier (SCR) manufactured by SMC Diode Solutions, rated for 800 V off-state voltage and 40 A on-state current in a through-hole TO-220-3 package. This component is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support, maintenance, and production continuity. Substitute parts must maintain electrical performance within the specified parameter ranges to ensure direct replacement capability without circuit redesign.

Substiute Parts

SCT840B

SMC Diode SolutionsIn Stock: 1072SCT840B Datasheet

Current PartRFQ

SCT840C

SMC Diode SolutionsIn Stock: 736SCT840C Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SCT840B is determined by strict equivalence across electrical and mechanical parameters. The primary substitute identified is the SCT840C, which shares the same base product number (SCT840) and manufacturer (SMC Diode Solutions). Substitution logic is based on the following criteria:

Electrical Parameter Equivalence:

• Off-state voltage rating (800 V minimum)
• Gate trigger voltage and current specifications
• On-state voltage and current ratings
• Hold current and off-state leakage current limits
• Non-repetitive surge current capability
• Operating temperature range compatibility

Mechanical & Packaging Equivalence:

• Through-hole mounting configuration
• TO-220-3 package footprint and pinout
• Physical dimensions and thermal characteristics

Compliance & Regulatory Equivalence:

• ECCN classification (EAR99)
• HTSUS commodity code (8541.30.0080)

The SCT840C maintains active product status, ensuring ongoing availability and manufacturer support, unlike the obsolete SCT840B.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: SCT840C

The SCT840C is the direct substitute for the obsolete SCT840B. Selection is based on the following engineering criteria:

1. Product Status Alignment: The SCT840C maintains active product status with SMC Diode Solutions, ensuring continued availability, technical documentation, and manufacturer support. The SCT840B is obsolete and subject to supply discontinuation.

2. Regulatory & Compliance Continuity: Both parts share identical ECCN (EAR99) and HTSUS (8541.30.0080) classifications, ensuring no change to export control or tariff treatment.

3. Electrical Parameter Compatibility: The SCT840C is specified within the same electrical performance envelope as the SCT840B across all critical parameters: 800 V off-state voltage, 40 A on-state current, gate trigger specifications, and thermal operating range.

4. Mechanical & Thermal Compatibility: Both parts utilize the TO-220-3 through-hole package, ensuring identical PCB footprint, mounting methodology, and thermal dissipation characteristics.

5. Supply Chain Continuity: Current inventory of SCT840C (719 Pcs New Original In Stock) supports immediate procurement without design modification or circuit redesign.

Frequently Asked Questions (FAQ)

Q: Can the SCT840C directly replace the SCT840B without PCB modification?

A: Yes. The SCT840C and SCT840B share identical package specifications (TO-220-3), pinout configuration, and through-hole mounting requirements. No PCB layout changes are necessary.

Q: What is the primary reason for substitution?

A: The SCT840B is classified as obsolete. The SCT840C, sharing the same base product number and manufacturer, provides continued availability and active manufacturer support.

Q: Are the electrical parameters identical between SCT840B and SCT840C?

A: Both parts are specified for 800 V off-state voltage, 40 A on-state current, and standard recovery SCR operation. Electrical performance is equivalent within the specified parameter ranges.

Q: Does substitution affect export compliance or tariff classification?

A: No. Both parts carry identical ECCN (EAR99) and HTSUS (8541.30.0080) classifications, ensuring no change to regulatory or trade treatment.

Q: Is thermal management affected by substitution?

A: No. Both parts operate within the same temperature range (-40°C to 150°C TJ) and utilize the same TO-220-3 package, which provides equivalent thermal dissipation characteristics.

Q: What inventory status should be considered for procurement?

A: The SCT840C has 719 Pcs New Original In Stock, supporting immediate availability. The SCT840B, though 967 Pcs are listed, is obsolete and should not be specified for new designs or long-term production.