DST5-120B39 Equivalent & Substitute Parts

Part Overview

The DST5-120B39 is a 12VA laminated core power transformer manufactured by Pulse Electronics, designed for through-hole mounting applications. It features dual primary and secondary windings with selectable voltage configurations (115V or 230V primary input; 60V parallel or 120V series secondary output). The part is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and component procurement.

Key Parameters

Parameter	Value
Power Rating	12VA
Primary Voltage	115V, 230V
Secondary Voltage (Full Load)	Parallel 60V, Series 120V
Secondary Current (Max)	Parallel 200mA, Series 100mA
Primary Winding Configuration	Dual
Secondary Winding Configuration	Dual
Core Type	Laminated
Mounting Type	Through Hole
Termination Style	PC Pin
Isolation Voltage	2500Vrms
Physical Dimensions	47.24mm L × 39.62mm W × 36.58mm H (max seated)

Substitute Part Grouping Explanation

Substitute parts for the DST5-120B39 are qualified based on electrical and mechanical parameter equivalence within the following criteria:

Identical power rating (12VA)
Matching primary voltage options (115V, 230V)
Matching secondary voltage configuration (Parallel 60V, Series 120V)
Matching secondary current capacity (Parallel 200mA, Series 100mA)
Identical winding configuration (Dual primary, Dual secondary)
Identical core type (Laminated)
Compatible mounting (Through Hole) and termination (PC Pin)
Equivalent isolation voltage (2500Vrms)
Physical dimensions within acceptable tolerance for through-hole PCB mounting

Two active substitute parts meet these criteria: DST-5-120 (Signal Transformer) and FS120-100 (Triad Magnetics).

Parameter Comparison

Parameter	DST5-120B39 (Pulse Electronics)	DST-5-120 (Signal Transformer)	FS120-100 (Triad Magnetics)
Power Rating	12VA	12VA	12VA
Primary Voltage	115V, 230V	115V, 230V	115V, 230V
Secondary Voltage (Full Load)	Parallel 60V, Series 120V	Parallel 60V, Series 120V	Parallel 60V, Series 120V
Secondary Current (Max)	Parallel 200mA, Series 100mA	Parallel 200mA, Series 100mA	Parallel 200mA, Series 100mA
Primary Winding(s)	Dual	Dual	Dual
Secondary Winding(s)	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	47.24mm	47.80mm	47.63mm
Width	39.62mm	39.60mm	39.67mm
Height (Max Seated)	36.58mm	36.90mm	36.50mm
Weight	0.7 lb (317.51 g)	0.7 lb (317.51 g)	0.7 lb (317.51 g)
RoHS Status	RoHS Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

Both DST-5-120 and FS120-100 are functionally equivalent to the obsolete DST5-120B39 based on electrical specifications and mechanical compatibility. Selection between these two active alternatives should be based on the following factors:

DST-5-120 (Signal Transformer): Active product status with ROHS3 compliance. Dimensions are within 0.56mm length tolerance and 0.30mm width tolerance of the original part. Suitable for direct replacement in existing through-hole PCB designs.

FS120-100 (Triad Magnetics): Active product status with ROHS3 compliance. Dimensions are within 0.39mm length tolerance and 0.05mm width tolerance of the original part, offering the closest physical match. Suitable for direct replacement in existing through-hole PCB designs.

Both parts maintain identical electrical performance, isolation voltage, and compliance certifications. Physical dimension variations are negligible for standard through-hole mounting applications.

Frequently Asked Questions (FAQ)

Q: Can DST-5-120 or FS120-100 be used as direct replacements for DST5-120B39?

A: Yes. Both parts are electrically and mechanically equivalent. All critical parameters—power rating, voltage configurations, current capacity, winding configuration, core type, mounting type, termination style, and isolation voltage—are identical. Physical dimensions are within acceptable tolerance for through-hole PCB mounting.

Q: What is the primary reason for finding substitutes for DST5-120B39?

A: The DST5-120B39 is classified as obsolete. DST-5-120 and FS120-100 are active products from alternative manufacturers, ensuring ongoing availability and supply chain continuity.

Q: Are there compliance differences between the original and substitute parts?

A: The original DST5-120B39 is RoHS Compliant. Both substitute parts are ROHS3 Compliant, which represents a more recent and stringent standard. Both maintain REACH Unaffected status. These differences represent improved compliance posture.

Q: Do the physical dimension variations affect PCB compatibility?

A: No. All three parts are designed for through-hole mounting with PC pin termination. Dimension variations (maximum 0.56mm in length, 0.30mm in width, 0.40mm in height) are within standard PCB tolerance for component placement and do not affect electrical performance or mechanical fit.

Q: Which substitute part offers the closest physical match to the original?

A: FS120-100 provides the closest dimensional match, with maximum tolerance variations of 0.39mm in length and 0.05mm in width. DST-5-120 is also within acceptable tolerance with maximum variations of 0.56mm in length and 0.30mm in width.

Q: Are packaging differences significant for component procurement?

A: DST-5-120 is supplied in Bulk packaging, while FS120-100 is supplied in Box packaging. Packaging format does not affect electrical or mechanical performance and is a procurement consideration only.

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