SH350 Gas Discharge Tube - Equivalent & Substitute Parts

Part Overview

The SH350 is a 2-pole surface mount gas discharge tube (GDT) manufactured by Littelfuse Inc., designed for overvoltage protection applications. With a DC spark-over voltage of 350V and impulse discharge current rating of 5000A (5kA), this component provides transient suppression in electronic circuits. The part is currently in active production status with full RoHS3 compliance and unlimited moisture sensitivity rating (MSL 1). Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, supply chain considerations, or design flexibility needs.

Substiute Parts

SH350

Littelfuse Inc.In Stock: 1683SH350 Datasheet

Current PartRFQ

2035-35-SM-RPLF

Bourns Inc.In Stock: 138982035-35-SM-RPLF Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SH350 is determined by strict equivalence across the following parameters:

• Voltage - DC Spark Over (Nominal): Must be 350V. This parameter directly determines the protection threshold and cannot vary.
• Impulse Discharge Current (8/20µs): Must be 5000A (5kA). This rating defines the maximum transient energy the component can safely dissipate.
• Number of Poles: Must be 2. The circuit topology requires a 2-pole configuration.
• Mounting Type: Must be Surface Mount. PCB assembly processes and footprints are designed for SMD components.
• Fail Short Characteristic: Must be No. The failure mode is specified for the application.
• RoHS Status: Must be ROHS3 Compliant. Regulatory requirements mandate this compliance level.
• Moisture Sensitivity Level (MSL): Must be 1 (Unlimited). Storage and handling procedures are based on this rating.

The 2035-35-SM-RPLF manufactured by Bourns Inc. meets all substitution criteria. Minor variations in tolerance specification (±15% for the Bourns part versus unspecified for the Littelfuse part) and package geometry (2-SMD Cylinder Square End versus 2-SMD Square End Block) do not preclude substitution when electrical parameters and compliance requirements are identical.

Parameter Comparison

Engineering Selection Recommendations

Both the SH350 (Littelfuse Inc.) and 2035-35-SM-RPLF (Bourns Inc.) are active production components with identical electrical specifications and full regulatory compliance. Selection between these parts may be based on:

• Supply availability: The Bourns 2035-35-SM-RPLF currently has higher inventory (13,880 pcs) compared to the Littelfuse SH350 (1,646 pcs).
• Compliance requirements: Both parts meet ROHS3 and REACH requirements with identical ECCN and HTSUS classifications, ensuring regulatory equivalence.
• Packaging and handling: Both components have MSL 1 (Unlimited) ratings, eliminating moisture sensitivity constraints during storage and assembly.
• Tolerance specification: The Bourns part specifies ±15% tolerance on spark-over voltage, while the Littelfuse part does not specify tolerance. This difference does not affect substitution eligibility when the nominal voltage requirement is 350V.

Frequently Asked Questions (FAQ)

Q: Can the 2035-35-SM-RPLF be used as a direct replacement for the SH350?

A: Yes. Both components have identical DC spark-over voltage (350V), impulse discharge current (5000A), pole configuration (2-pole), mounting type (surface mount), and fail-short characteristic (No). All critical electrical and mechanical parameters match.

Q: Are there differences in the package geometry between these parts?

A: The SH350 uses a 2-SMD Square End Block package, while the 2035-35-SM-RPLF uses a 2-SMD Cylinder Square End package. Both are surface mount configurations with compatible footprints for standard PCB assembly processes. Verify footprint compatibility with your PCB design files before production.

Q: Do both parts have the same regulatory compliance?

A: Yes. Both the SH350 and 2035-35-SM-RPLF are ROHS3 Compliant, REACH Unaffected, classified as EAR99, and share the same HTSUS code (8536.30.8000).

Q: What is the significance of the ±15% tolerance specification on the Bourns part?

A: The Bourns 2035-35-SM-RPLF specifies ±15% tolerance on the DC spark-over voltage, meaning the actual spark-over voltage will fall between 297.5V and 402.5V. The Littelfuse SH350 does not specify tolerance. Both parts are rated at 350V nominal and are electrically equivalent for substitution purposes.

Q: Are there any moisture sensitivity concerns with either part?

A: No. Both components have MSL 1 (Unlimited) ratings, indicating no moisture sensitivity constraints. Standard storage and handling procedures apply without special desiccant or humidity control requirements.

Q: Can I use these parts interchangeably in existing designs?

A: Yes, provided your PCB footprint accommodates the 2-SMD package geometry. Verify that the physical dimensions and pad layout of the 2-SMD Cylinder Square End (Bourns) match your design specifications, which were originally developed for the 2-SMD Square End Block (Littelfuse).