Littelfuse S201E SCR 200V 1A TO-92 Equivalent & Substitute Parts

Part Overview

The Littelfuse S201E is a Silicon Controlled Rectifier (SCR) rated for 200V off-state voltage with 1A RMS on-state current in a TO-92 through-hole package. This component is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing system support and new design implementations. The S201E serves as a standard recovery thyristor suitable for AC switching and control applications within its voltage and current specifications.

Substiute Parts

S201E

Littelfuse Inc.In Stock: 1210S201E Datasheet

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S401E

Littelfuse Inc.In Stock: 4473S401E Datasheet

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S601E

Littelfuse Inc.In Stock: 2908S601E Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the S201E is determined by compatibility across the following critical parameters:

Mandatory Compatibility Criteria:

• SCR Type: Standard Recovery
• Mounting Type: Through Hole
• Package / Case: TO-226-3, TO-92-3 (TO-226AA)
• Gate Trigger Voltage (Vgt) Max: 1.5V
• Gate Trigger Current (Igt) Max: 10mA
• On-State Voltage (Vtm) Max: 1.6V
• Current - Hold (Ih) Max: 30mA
• Current - Off State Max: 10µA
• Operating Temperature Range: -40°C to 125°C
• RoHS Status: ROHS3 Compliant

Allowable Variation Parameter:

• Voltage - Off State: The S201E operates at 200V. Substitute parts with higher off-state voltage ratings (400V, 600V) are acceptable as they maintain backward compatibility with 200V applications while providing enhanced voltage margin.

The S401E (400V) and S601E (600V) meet all mandatory criteria and represent voltage-upgraded alternatives suitable for applications requiring higher voltage headroom or system standardization.

Parameter Comparison

Engineering Selection Recommendations

Product Status Consideration: The S201E is classified as obsolete, while both S401E and S601E maintain active product status with current manufacturing and distribution support. For new designs or system replacements, selection of an active substitute part ensures long-term component availability and supply chain continuity.

Compliance and Certification: All three parts—S201E, S401E, and S601E—are ROHS3 compliant and carry MSL rating of 1 (Unlimited), indicating equivalent environmental and regulatory compliance. No additional qualification is required from a compliance perspective when substituting between these parts.

Voltage Rating Selection:

• Use S401E (400V) for applications requiring moderate voltage margin above the 200V nominal specification.
• Use S601E (600V) for applications requiring maximum voltage headroom or where system voltage standardization on higher-rated components is preferred.

Both substitute parts are electrically and mechanically compatible with the S201E across all functional parameters except off-state voltage, where the higher ratings provide enhanced performance margin.

Frequently Asked Questions (FAQ)

Q: Can the S401E or S601E directly replace the S201E in existing circuits? A: Yes. The S401E and S601E are direct replacements for the S201E. All gate trigger characteristics, on-state parameters, hold current, and thermal specifications are identical. The higher voltage ratings (400V and 600V respectively) provide additional voltage margin while maintaining full backward compatibility with 200V applications.

Q: What is the primary difference between S201E, S401E, and S601E? A: The primary difference is the off-state voltage rating: S201E is rated for 200V, S401E for 400V, and S601E for 600V. All other electrical and mechanical parameters are identical. The voltage rating determines the maximum reverse voltage the SCR can withstand without conducting.

Q: Why is the S201E obsolete while S401E and S601E are active? A: The S201E has been discontinued by Littelfuse Inc., but the higher-voltage variants remain in active production. This is common in component lifecycle management where manufacturers consolidate product lines around higher-performance or more versatile ratings.

Q: Are there any package or pinout differences between these parts? A: No. All three parts use the identical TO-226-3 / TO-92-3 (TO-226AA) through-hole package with the same pinout and mechanical dimensions. Direct PCB substitution is possible without layout modifications.

Q: What are the gate trigger specifications, and are they the same across all three parts? A: Yes. All three parts have identical gate trigger specifications: maximum gate trigger voltage (Vgt) of 1.5V and maximum gate trigger current (Igt) of 10mA. Gate drive circuits designed for the S201E require no modification when using S401E or S601E substitutes.

Q: Which substitute should I select for a new design? A: For new designs, the S601E (600V) is recommended as it provides the highest voltage margin and maintains active product status. However, if the application circuit is constrained to lower voltage levels, the S401E (400V) offers a balanced alternative with equivalent availability and compliance.

Q: Are all three parts RoHS compliant? A: Yes. The S201E, S401E, and S601E are all ROHS3 compliant with MSL rating of 1 (Unlimited), meeting current environmental and regulatory requirements for industrial and commercial applications.