DST3-28B21 Equivalent & Substitute Parts

Part Overview

The DST3-28B21 is a laminated core power transformer manufactured by Pulse Electronics, rated at 2.4VA with dual primary and secondary windings. This through-hole mounted component is designed for applications requiring 115V or 230V primary input with configurable secondary output of 14V (parallel) or 28V (series). The product is active and widely stocked, with 959 units available in inventory. Equivalent and substitute parts are identified when component availability changes, supply chain disruptions occur, or design flexibility is required while maintaining electrical and mechanical compatibility.

Key Parameters

Parameter	Value
Power Rating	2.4VA
Primary Voltage	115V, 230V
Secondary Voltage (Parallel)	14V
Secondary Voltage (Series)	28V
Output Current - Parallel	170mA
Output Current - Series	85mA
Primary Windings	Dual
Secondary Windings	Dual
Core Type	Laminated
Mounting Type	Through Hole
Termination Style	PC Pin
Isolation Voltage	2500Vrms
RoHS Status	RoHS Compliant

Substitute Part Grouping Explanation

Substitute parts for the DST3-28B21 are qualified based on strict electrical and mechanical parameter matching. The following criteria determine substitutability:

Electrical Parameters (Must Match):

Power rating: 2.4VA
Primary voltage options: 115V, 230V
Secondary voltage configuration: Parallel 14V / Series 28V
Output current capacity: Parallel 170mA / Series 85mA
Winding configuration: Dual primary, dual secondary
Isolation voltage: 2500Vrms
Core type: Laminated

Mechanical Parameters (Must Match):

Mounting type: Through Hole
Termination style: PC Pin
Physical dimensions: Within tolerance of original specification
Height seated (maximum): Approximately 30mm range

Compliance Parameters:

RoHS compliance status
ECCN and HTSUS classifications

The identified substitutes meet all electrical specifications and maintain mechanical compatibility with the original design. Dimensional variations are within acceptable tolerances for through-hole mounting applications.

Parameter Comparison

Parameter	DST3-28B21 (Pulse Electronics)	162E28 (Hammond Manufacturing)	3FD-328 (Tamura)
Power Rating	2.4VA	2.4VA	2.4VA
Primary Voltage	115V, 230V	115V, 230V	115V, 230V
Secondary Voltage (Parallel)	14V	14V	14V
Secondary Voltage (Series)	28V	28V	28V
Output Current - Parallel	170mA	170mA	170mA
Output Current - Series	85mA	85mA	85mA
Primary Windings	Dual	Dual	Dual
Secondary Windings	Dual	Dual	Dual
Core Type	Laminated	Laminated	Laminated
Mounting Type	Through Hole	Through Hole	Through Hole
Termination Style	PC Pin	PC Pin	PC Pin
Isolation Voltage	2500Vrms	2500Vrms	2500Vrms
Length	35.05mm	34.93mm	35.56mm
Width	28.70mm	28.58mm	31.00mm
Height (Seated Max)	30.23mm	30.15mm	32.10mm
RoHS Status	RoHS Compliant	ROHS3 Compliant	RoHS Compliant
Product Status	Active	Active	Active

Engineering Selection Recommendations

All three parts—DST3-28B21, 162E28, and 3FD-328—are active products with full electrical and mechanical compatibility. Selection between these transformers should be based on the following factors:

DST3-28B21 (Pulse Electronics): Primary choice with 959 units in stock. RoHS Compliant status confirmed. Dimensions: 35.05mm L × 28.70mm W × 30.23mm H. Suitable for standard through-hole PCB applications with standard spacing requirements.

162E28 (Hammond Manufacturing): Direct equivalent with 670 units available. ROHS3 Compliant certification. Dimensions: 34.93mm L × 28.58mm W × 30.15mm H. Minimal dimensional variation from primary part. Bulk packaging available.

3FD-328 (Tamura): Highest inventory availability with 2296 units in stock. RoHS Compliant status. Dimensions: 35.56mm L × 31.00mm W × 32.10mm H. Slightly larger footprint; verify PCB layout clearance before substitution. Supplied in tube packaging.

All parts carry identical electrical specifications and meet the same isolation voltage and compliance requirements. Dimensional differences are within acceptable tolerances for through-hole mounting applications.

Frequently Asked Questions (FAQ)

Q: Can the 162E28 be used as a direct replacement for the DST3-28B21?

A: Yes. The 162E28 meets all electrical specifications including power rating, voltage configuration, current capacity, and isolation voltage. Dimensional variation is minimal (within 0.12mm on length and 0.12mm on width), making it suitable for direct PCB substitution.

Q: What are the dimensional constraints when substituting the 3FD-328?

A: The 3FD-328 has a larger footprint: 35.56mm L × 31.00mm W × 32.10mm H compared to the DST3-28B21 at 35.05mm L × 28.70mm W × 30.23mm H. Verify that your PCB layout provides sufficient clearance, particularly in the width and height dimensions, before implementing this substitution.

Q: Are all three parts RoHS compliant?

A: Yes. The DST3-28B21 and 3FD-328 are RoHS Compliant. The 162E28 carries ROHS3 Compliant certification, which represents an updated compliance standard. All three parts meet RoHS requirements.

Q: What is the difference between the packaging options?

A: DST3-28B21 is supplied with standard packaging. The 162E28 is available in bulk packaging. The 3FD-328 is supplied in tube packaging. Packaging does not affect electrical or mechanical performance; selection depends on procurement and handling requirements.

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

A: Yes. All three parts feature dual primary and dual secondary windings, enabling both series (28V, 85mA) and parallel (14V, 170mA) output configurations. Electrical performance is identical across all three parts for both configurations.

Q: What isolation voltage do these transformers provide?

A: All three parts provide 2500Vrms isolation voltage, meeting the same safety and regulatory requirements.

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