ST-3-20 Equivalent & Substitute Parts

Part Overview

The ST-3-20 is a laminated core power transformer manufactured by Signal Transformer, rated at 2.4VA with a 115V primary voltage and dual secondary windings capable of 10V parallel or 20V series output. This through-hole mounted component is designed for applications requiring isolated AC power conversion in compact form factors. The part is currently active in production with full RoHS3 compliance and 2500Vrms isolation rating. Substitute parts are identified when equivalent electrical performance, mechanical compatibility, and regulatory compliance can be maintained across alternative manufacturers.

Substiute Parts

ST-3-20

Signal TransformerIn Stock: 1136ST-3-20 Datasheet

Current PartRFQ

3FS-320

TamuraIn Stock: 8883FS-320 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the ST-3-20 is determined by strict equivalence across the following critical parameters:

• Electrical Performance: Primary voltage (115V), secondary voltage configuration (Parallel 10V / Series 20V), maximum output current (Parallel 240mA / Series 120mA), and power rating (2.4VA)
• Isolation Specification: Voltage isolation rating of 2500Vrms
• Winding Configuration: Single primary winding and dual secondary windings
• Mechanical Compatibility: Through-hole mounting with PC pin termination
• Regulatory Compliance: RoHS compliance status and ECCN classification (EAR99)

The 3FS-320 manufactured by Tamura meets all substitution criteria, maintaining identical electrical specifications, isolation voltage, winding configuration, and mounting characteristics while preserving regulatory compliance.

Parameter Comparison

Engineering Selection Recommendations

Both the ST-3-20 and 3FS-320 are active production components with full regulatory compliance. The ST-3-20 carries RoHS3 certification, while the 3FS-320 maintains RoHS compliance. Both parts share identical electrical specifications, isolation ratings, and mechanical mounting characteristics, making them functionally interchangeable in applications requiring 2.4VA laminated core power transformation with dual secondary windings.

Selection between these parts may be influenced by packaging format (ST-3-20 supplied in box; 3FS-320 supplied in tube), physical dimensions (ST-3-20: 34.90mm L × 28.60mm W × 30.80mm H; 3FS-320: 35.56mm L × 31.00mm W × 32.10mm H), and inventory availability. Both parts are classified under HTSUS code 8504.31.4035 and carry EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can the 3FS-320 be used as a direct replacement for the ST-3-20?

A: Yes. The 3FS-320 meets all electrical and mechanical substitution criteria, including identical power rating, voltage specifications, winding configuration, isolation voltage, and mounting type. Both parts are active production components with appropriate regulatory compliance.

Q: Are there dimensional differences between these parts?

A: Minor dimensional variations exist. The ST-3-20 measures 34.90mm L × 28.60mm W × 30.80mm H, while the 3FS-320 measures 35.56mm L × 31.00mm W × 32.10mm H. These differences should be evaluated against available PCB space and mechanical constraints in the target application.

Q: What is the difference in packaging between these parts?

A: The ST-3-20 is supplied in box packaging, while the 3FS-320 is supplied in tube packaging. This distinction affects handling, storage, and integration into automated assembly processes.

Q: Do both parts meet the same regulatory requirements?

A: Both parts are RoHS compliant and carry EAR99 export classification under HTSUS code 8504.31.4035. The ST-3-20 specifically carries RoHS3 certification, while the 3FS-320 maintains RoHS compliance. Both meet the isolation voltage requirement of 2500Vrms.

Q: What determines whether a part can substitute for the ST-3-20?

A: Substitution is determined by equivalence in power rating (2.4VA), primary voltage (115V), secondary voltage configuration (Parallel 10V / Series 20V), maximum output current (Parallel 240mA / Series 120mA), winding configuration (single primary, dual secondary), isolation voltage (2500Vrms), mounting type (through-hole), and termination style (PC pin).