ST3-20B13 Equivalent & Substitute Parts

Part Overview

The ST3-20B13 is a laminated core power transformer manufactured by Pulse Electronics, rated at 2.4VA with dual secondary windings capable of 10V parallel or 20V series output configurations. This through-hole component is designed for applications requiring isolated AC power conversion with 2500Vrms isolation voltage.

The ST3-20B13 is classified as obsolete. Identifying equivalent substitute parts is essential for maintaining design continuity, ensuring supply chain reliability, and supporting legacy system repairs and production requirements.

Substiute Parts

ST3-20B13

Pulse ElectronicsIn Stock: 1091ST3-20B13 Datasheet

Current PartRFQ

3FS-320

TamuraIn Stock: 8883FS-320 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ST3-20B13 is determined by strict equivalence across the following critical parameters:

• Power Rating: 2.4VA (exact match required)
• Primary Voltage: 115V (exact match required)
• Secondary Voltage Configuration: Dual secondary windings with 10V parallel and 20V series capability (exact match required)
• Secondary Current Capability: 240mA parallel, 120mA series (exact match required)
• Winding Configuration: Single primary, dual secondary, no center tap (exact match required)
• Mounting and Termination: Through-hole mounting with PC pin termination (exact match required)
• Isolation Voltage: 2500Vrms (exact match required)
• Core Type: Laminated core construction (exact match required)

The 3FS-320 manufactured by Tamura meets all critical electrical and mechanical substitution criteria for the ST3-20B13.

Parameter Comparison

Engineering Selection Recommendations

The 3FS-320 is the qualified substitute for the ST3-20B13 based on the following factors:

Electrical Equivalence: All primary and secondary voltage, current, and power specifications are identical. Isolation voltage and winding configurations match exactly.

Mechanical Compatibility: Physical dimensions are within acceptable tolerance for through-hole PCB mounting. Both components use PC pin termination compatible with standard PCB footprints.

Compliance and Certification: Both components are RoHS compliant and carry MSL rating 1 (unlimited moisture sensitivity). Both are classified under the same HTSUS code (8504.31.4035) and ECCN (EAR99).

Product Status Advantage: The 3FS-320 is classified as active product status, ensuring ongoing availability and supply chain support compared to the obsolete ST3-20B13.

Frequently Asked Questions (FAQ)

Q: Can the 3FS-320 be used as a direct replacement for the ST3-20B13 in existing designs?

A: Yes. The 3FS-320 meets all electrical and mechanical specifications of the ST3-20B13. Physical dimensions are within acceptable tolerance for standard through-hole PCB layouts. No circuit modifications are required.

Q: What are the key differences between these two transformers?

A: The primary difference is product status: the ST3-20B13 is obsolete while the 3FS-320 is active. Physical dimensions vary slightly (length, width, and height within tolerance). All electrical parameters are identical.

Q: Are there any packaging differences between the ST3-20B13 and 3FS-320?

A: The ST3-20B13 is supplied with standard packaging, while the 3FS-320 is supplied in tube packaging. Both are suitable for PCB assembly processes.

Q: Do both transformers meet the same compliance standards?

A: Yes. Both the ST3-20B13 and 3FS-320 are RoHS compliant, carry MSL rating 1, and are classified under identical HTSUS and ECCN codes.

Q: What should be verified when substituting the 3FS-320 for the ST3-20B13?

A: Confirm that the PCB footprint accommodates the 3FS-320 dimensions (35.56mm L × 31.00mm W × 32.10mm H seated). Verify that the through-hole spacing and PC pin configuration align with existing PCB design. Both components are electrically and mechanically compatible without design changes.