S4040RQ3TP Equivalent & Substitute Parts

Part Overview

The S4040RQ3TP is a Silicon Controlled Rectifier (SCR) manufactured by Littelfuse Inc., rated for 400V off-state voltage and 40A RMS on-state current. This thyristor is designed for standard recovery applications in through-hole TO-220AB-R packaging. The component is Active status and ROHS3 compliant, suitable for industrial switching and power control circuits operating across -40°C to 125°C temperature range. Substitute parts are identified when electrical parameters and mechanical compatibility align with application requirements.

Substiute Parts

S4040RQ3TP

Littelfuse Inc.In Stock: 849S4040RQ3TP Datasheet

Current PartRFQ

S4040RQ2TP

Littelfuse Inc.In Stock: 1938S4040RQ2TP Datasheet

Parametric EquivalentRFQ

S4055RTP

Littelfuse Inc.In Stock: 1394S4055RTP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the S4040RQ3TP is determined by matching the following critical parameters:

• Off-state voltage rating: 400V
• SCR type classification: Standard Recovery
• Gate trigger voltage and current specifications: Vgt ≤ 1.5V, Igt ≤ 40mA
• On-state voltage drop: Vtm ≤ 1.8V
• Hold current: Ih ≤ 60mA
• Package type: TO-220-3 form factor
• Operating temperature range: -40°C to 125°C minimum
• Compliance status: ROHS3, REACH Unaffected

Two substitute parts meet these criteria: S4040RQ2TP and S4055RTP. Both are Littelfuse Inc. thyristors with identical voltage ratings, gate characteristics, and temperature specifications. Differences exist in on-state current ratings and packaging tab configuration, which determine application suitability.

Parameter Comparison

Engineering Selection Recommendations

S4040RQ2TP serves as a direct parametric equivalent to S4040RQ3TP. Both components share identical electrical specifications for voltage, gate trigger characteristics, and on-state current ratings. The primary distinction is the supplier device package: S4040RQ3TP uses TO-220AB-R (isolated tab), while S4040RQ2TP uses TO-220 Non-Isolated Tab configuration. Selection between these two depends on circuit board layout and thermal management requirements specific to the isolated or non-isolated tab design.

S4055RTP is a higher current-rated alternative, providing 55A RMS on-state current compared to 40A in the S4040RQ3TP. This substitute is suitable for applications requiring increased current capacity while maintaining identical voltage ratings and gate control specifications. The S4055RTP also features higher non-repetitive surge current ratings (550A/650A versus 430A/520A). All three parts maintain Active product status and full ROHS3 and REACH compliance.

Frequently Asked Questions (FAQ)

Q: Can S4040RQ2TP replace S4040RQ3TP in existing designs?

A: S4040RQ2TP is electrically equivalent with identical voltage and current ratings. Compatibility depends on the circuit board's tab isolation requirements. If the design uses an isolated tab (TO-220AB-R), the non-isolated tab configuration of S4040RQ2TP may require layout modifications.

Q: When should S4055RTP be selected instead of S4040RQ3TP?

A: S4055RTP is selected when the application requires higher on-state current capacity (55A RMS versus 40A RMS) or higher surge current handling (550A/650A versus 430A/520A). All other electrical parameters remain identical, making it suitable for higher-power variants of the same circuit topology.

Q: Are all three parts pin-compatible?

A: All three parts use TO-220-3 package configuration with identical pin assignments. Physical mounting is compatible. The difference between S4040RQ3TP and S4040RQ2TP lies in tab isolation, which affects thermal and electrical isolation properties but not pin connectivity.

Q: Do these parts require different gate drive circuits?

A: No. All three parts share identical gate trigger voltage (1.5V max) and gate trigger current (40mA max) specifications, allowing the same gate drive circuit design to be used across all three components.

Q: What is the inventory status for these substitute parts?

A: S4040RQ3TP: 799 Pcs; S4040RQ2TP: 1871 Pcs; S4055RTP: 1361 Pcs. All are listed as New Original In Stock.