Equivalent & Substitute Parts: 3FS-320

Part Overview

The 3FS-320 is a laminated core power transformer manufactured by Tamura, rated at 2.4VA with a 115V primary voltage and dual secondary windings configured for parallel (10V, 240mA) or series (20V, 120mA) operation. This through-hole mounted component is designed for PC pin termination and is currently in active production status with RoHS compliance certification.

Substitute parts are identified to address inventory availability, lead time constraints, or end-of-life considerations while maintaining electrical and mechanical compatibility within the specified parameter tolerances for this transformer category.

Key Parameters

Parameter	Value	Specification Type
Primary Voltage	115V	Electrical - Critical
Secondary Voltage (Parallel)	10V	Electrical - Critical
Secondary Voltage (Series)	20V	Electrical - Critical
Output Current - Parallel	240mA	Electrical - Critical
Output Current - Series	120mA	Electrical - Critical
Power Rating	2.4VA	Electrical - Critical
Core Type	Laminated	Mechanical - Critical
Mounting Type	Through Hole	Mechanical - Critical
Termination Style	PC Pin	Mechanical - Critical
Isolation Voltage	2500Vrms	Electrical - Safety
Primary Winding Configuration	Single	Electrical - Critical
Secondary Winding Configuration	Dual	Electrical - Critical
Center Tap	No	Electrical - Critical
RoHS Compliance	Compliant	Regulatory

Substitute Part Grouping Explanation

Substitution eligibility for the 3FS-320 is determined by strict equivalence across the following critical parameters:

Electrical Parameters (Must Match Exactly):

Primary voltage: 115V
Secondary voltage configuration: Parallel 10V and Series 20V
Output current capability: Parallel 240mA and Series 120mA
Power rating: Minimum 2.4VA
Isolation voltage: 2500Vrms
Winding configuration: Single primary, dual secondary, no center tap

Mechanical Parameters (Must Match Exactly):

Core type: Laminated
Mounting type: Through hole
Termination style: PC pin

Regulatory Parameters:

RoHS compliance status: Compliant or equivalent regulatory certification

The F20-120 manufactured by Triad Magnetics meets all critical electrical and mechanical parameters. The 2.5VA power rating of the F20-120 exceeds the 2.4VA requirement, providing operational margin. Dimensional variations (length, width, height) are within acceptable tolerances for through-hole PCB mounting applications. Both parts carry equivalent regulatory certifications (RoHS3 compliance for F20-120 versus RoHS compliance for 3FS-320).

Parameter Comparison

Parameter	3FS-320 (Tamura)	F20-120 (Triad Magnetics)	Match Status
Manufacturer	Tamura	Triad Magnetics	Different
Primary Voltage	115V	115V	Equivalent
Secondary Voltage - Parallel	10V	10V	Equivalent
Secondary Voltage - Series	20V	20V	Equivalent
Output Current - Parallel	240mA	240mA	Equivalent
Output Current - Series	120mA	120mA	Equivalent
Power Rating	2.4VA	2.5VA	Equivalent (F20-120 exceeds)
Core Type	Laminated	Laminated	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Termination Style	PC Pin	PC Pin	Equivalent
Isolation Voltage	2500Vrms	2500Vrms	Equivalent
Primary Winding(s)	Single	Single	Equivalent
Secondary Winding(s)	Dual	Dual	Equivalent
Center Tap	No	No	Equivalent
RoHS Status	RoHS Compliant	ROHS3 Compliant	Equivalent
Length	35.56mm	34.93mm	Within tolerance
Width	31.00mm	28.58mm	Within tolerance
Height - Seated (Max)	32.10mm	30.15mm	Within tolerance

Engineering Selection Recommendations

Primary Part Selection (3FS-320): The 3FS-320 is recommended as the primary selection when available. This part is in active production status with established supply chain presence (804 units in stock). RoHS compliance certification confirms regulatory alignment for current manufacturing standards.

Substitute Part Selection (F20-120): The F20-120 is qualified as a direct substitute when 3FS-320 availability is constrained. This part meets all critical electrical specifications with equivalent isolation voltage and winding configuration. The 2.5VA power rating provides operational margin above the 2.4VA requirement. ROHS3 compliance certification indicates current regulatory status. Inventory availability (756 units in stock) supports supply continuity. Dimensional variations are acceptable for through-hole PCB mounting applications without requiring circuit board redesign.

Both parts carry active production status, confirming long-term availability and supply chain stability for production applications.

Frequently Asked Questions (FAQ)

Q: Can the F20-120 be used as a direct replacement for the 3FS-320 in existing designs?

A: Yes. The F20-120 meets all critical electrical parameters (primary voltage, secondary voltages, output currents, isolation voltage, and winding configuration) and mechanical parameters (laminated core, through-hole mounting, PC pin termination). Dimensional variations are within acceptable tolerances for PCB mounting. No circuit redesign is required.

Q: What is the significance of the 2.5VA rating on the F20-120 compared to the 2.4VA rating on the 3FS-320?

A: The F20-120 power rating exceeds the 3FS-320 specification, providing operational margin. This higher rating does not create incompatibility; it indicates the F20-120 can deliver the required 2.4VA output with additional capacity headroom.

Q: Are there differences in packaging between these parts?

A: Yes. The 3FS-320 is supplied in tube packaging, while the F20-120 is supplied in box packaging. This difference affects receiving, storage, and handling procedures but does not impact electrical or mechanical performance in the application.

Q: Do both parts meet current regulatory requirements?

A: Yes. The 3FS-320 carries RoHS compliance certification, and the F20-120 carries ROHS3 compliance certification. Both certifications confirm compliance with current lead-free and hazardous substance restrictions for electronic components.

Q: What are the key parameters that determine substitution eligibility?

A: Substitution is determined by equivalence in primary voltage (115V), secondary voltage configuration (parallel 10V / series 20V), output current capability (parallel 240mA / series 120mA), isolation voltage (2500Vrms), core type (laminated), mounting type (through-hole), termination style (PC pin), and winding configuration (single primary, dual secondary, no center tap).

Q: Can these transformers be used interchangeably in parallel or series configurations?

A: Yes. Both the 3FS-320 and F20-120 support dual secondary winding configurations allowing parallel connection (10V, 240mA) or series connection (20V, 120mA) operation. The winding configuration is identical between parts.

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