Equivalent & Substitute Parts: 3FD-556 Laminated Power Transformer

Part Overview

The 3FD-556 is a 12VA laminated core power transformer manufactured by Tamura, designed for through-hole mounting applications. This transformer features dual primary and secondary windings with selectable output configurations (parallel 28V or series 56V) and operates at primary voltages of 115V or 230V. The component is currently in active production status with 706 units in stock. Substitute parts are identified when inventory constraints, lead time requirements, or specific packaging preferences necessitate alternative sourcing while maintaining full electrical and mechanical compatibility.

Key Parameters

Parameter	Value	Specification Type
Power Rating	12VA	Electrical
Primary Voltage	115V, 230V	Electrical
Secondary Voltage (Parallel)	28V	Electrical
Secondary Voltage (Series)	56V	Electrical
Output Current - Parallel	440mA	Electrical
Output Current - Series	220mA	Electrical
Core Type	Laminated	Mechanical
Primary Windings	Dual	Electrical
Secondary Windings	Dual	Electrical
Isolation Voltage	2500Vrms	Electrical
Mounting Type	Through Hole	Mechanical
Termination Style	PC Pin	Mechanical
Dimensions (L x W)	48.50mm x 41.52mm	Mechanical
Height - Seated (Max)	38.00mm	Mechanical
RoHS Compliance	Compliant	Regulatory
Moisture Sensitivity Level	1 (Unlimited)	Environmental

Substitute Part Grouping Explanation

Substitution eligibility for the 3FD-556 is determined by strict equivalence across the following critical parameters:

Electrical Equivalence Requirements:

Identical power rating: 12VA
Matching primary voltage options: 115V and 230V
Matching secondary voltage configurations: parallel 28V and series 56V
Matching output current specifications: parallel 440mA and series 220mA
Identical isolation voltage: 2500Vrms
Identical winding configuration: dual primary and dual secondary

Mechanical Equivalence Requirements:

Identical core type: laminated
Identical mounting type: through hole
Identical termination style: PC pin
Compatible physical dimensions and height envelope

Regulatory Equivalence Requirements:

RoHS compliance status (RoHS Compliant or ROHS3 Compliant acceptable)

The substitute part FS56-220 (Triad Magnetics) meets all electrical and mechanical equivalence criteria. Dimensional variations (47.63mm L x 39.67mm W x 36.50mm H) remain within acceptable tolerance for through-hole mounting applications. Both parts share identical electrical specifications and regulatory compliance status.

Parameter Comparison

Parameter	3FD-556 (Tamura)	FS56-220 (Triad Magnetics)	Match Status
Manufacturer Part Number	3FD-556	FS56-220	Different
Power Rating	12VA	12VA	Equivalent
Primary Voltage	115V, 230V	115V, 230V	Equivalent
Secondary Voltage - Parallel	28V	28V	Equivalent
Secondary Voltage - Series	56V	56V	Equivalent
Output Current - Parallel	440mA	440mA	Equivalent
Output Current - Series	220mA	220mA	Equivalent
Core Type	Laminated	Laminated	Equivalent
Primary Windings	Dual	Dual	Equivalent
Secondary Windings	Dual	Dual	Equivalent
Isolation Voltage	2500Vrms	2500Vrms	Equivalent
Mounting Type	Through Hole	Through Hole	Equivalent
Termination Style	PC Pin	PC Pin	Equivalent
Length	48.50mm	47.63mm	Compatible
Width	41.52mm	39.67mm	Compatible
Height - Seated (Max)	38.00mm	36.50mm	Compatible
RoHS Status	RoHS Compliant	ROHS3 Compliant	Equivalent
Product Status	Active	Active	Equivalent
Packaging	Tube	Box	Different

Engineering Selection Recommendations

Primary Part Selection (3FD-556): The 3FD-556 is the preferred selection when Tamura sourcing is established and tube packaging is required for automated assembly processes. This part maintains active production status with 706 units in current inventory, ensuring supply continuity for ongoing production requirements.

Substitute Part Selection (FS56-220): The FS56-220 serves as a direct electrical and mechanical substitute when Triad Magnetics sourcing is preferred or when Tamura lead times exceed project requirements. This part is also in active production with 718 units available. The FS56-220 is packaged in box format, which may require manual handling in assembly operations compared to tube packaging. Both parts carry equivalent RoHS compliance certifications (RoHS Compliant vs. ROHS3 Compliant), confirming regulatory equivalence for applications subject to RoHS directives.

Dimensional Compatibility: The FS56-220 exhibits slightly smaller physical dimensions (1.17% reduction in length, 4.45% reduction in width, 3.95% reduction in height). These dimensional variations do not compromise through-hole mounting compatibility or circuit board layout requirements, as the substitute remains within acceptable mechanical envelope tolerances for this transformer category.

Compliance Verification: Both parts are RoHS compliant and carry identical ECCN (EAR99) and HTSUS (8504.31.4035) classifications, confirming regulatory and export control equivalence.

Frequently Asked Questions (FAQ)

Q: Can the FS56-220 be used as a direct replacement for the 3FD-556 in existing designs?

A: Yes. The FS56-220 provides full electrical equivalence across all specified parameters: 12VA power rating, dual 115V/230V primary windings, dual secondary windings with 28V parallel and 56V series configurations, 440mA parallel and 220mA series output currents, and 2500Vrms isolation voltage. Mechanical compatibility is confirmed through identical through-hole mounting and PC pin termination. Dimensional variations are within acceptable tolerances for PCB layout applications.

Q: What is the primary difference between these two parts?

A: The primary differences are manufacturer (Tamura vs. Triad Magnetics), packaging format (tube vs. box), and minor dimensional variations. All electrical specifications, winding configurations, and regulatory compliance certifications are identical.

Q: Does packaging format affect electrical performance?

A: No. Packaging format (tube vs. box) affects only material handling and assembly logistics, not electrical performance or component specifications. Both packaging formats protect the transformer during storage and transport.

Q: Are there any compliance or certification differences between these parts?

A: Both parts are RoHS compliant. The 3FD-556 carries RoHS Compliant status, while the FS56-220 carries ROHS3 Compliant status. Both certifications confirm lead-free construction and compliance with RoHS directives. Both parts share identical ECCN and HTSUS classifications.

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

A: Yes. Both the 3FD-556 and FS56-220 feature dual secondary windings that support both series (56V at 220mA) and parallel (28V at 440mA) output configurations. Configuration selection is determined by circuit design requirements, not component selection.

Q: What is the significance of the 2500Vrms isolation voltage specification?

A: The 2500Vrms isolation voltage specifies the maximum voltage that can be safely applied between primary and secondary windings without electrical breakdown. This specification is identical for both parts, confirming equivalent isolation performance in applications requiring galvanic isolation between input and output circuits.

Q: Are there any environmental or storage considerations for these transformers?

A: Both parts carry Moisture Sensitivity Level (MSL) 1 classification (3FD-556) or Not Applicable (FS56-220), indicating minimal moisture sensitivity. Standard component storage conditions are appropriate for both parts.

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