TOP257EG Equivalent & Substitute Parts Reference

Part Overview

The TOP257EG is an offline switch flyback converter IC manufactured by Power Integrations, part of the TOPSwitch®-HX series. This isolated power management IC operates at 66kHz or 132kHz switching frequency with a maximum power rating of 157W and 700V breakdown voltage. The device integrates an internal switch with comprehensive fault protection including current limiting, over-temperature, and over-voltage protection. The TOP257EG is Active product status with full RoHS compliance and unlimited moisture sensitivity rating (MSL 1).

Substitute parts are necessary when the original TOP257EG is unavailable, when inventory constraints require alternative sourcing, or when application requirements permit operation at different power levels within the TOPSwitch®-HX family specifications.

Key Parameters

Parameter	Value
Manufacturer	Power Integrations
Series	TOPSwitch®-HX
Topology	Flyback
Output Isolation	Isolated
Voltage - Breakdown	700V
Frequency - Switching	66kHz, 132kHz
Power (Watts)	157W
Duty Cycle	78%
Fault Protection	Current Limiting, Over Temperature, Over Voltage
Operating Temperature	-40°C ~ 150°C (TJ)
Package / Case	7-SSIP, 6 Leads, Exposed Pad, Formed Leads
Supplier Device Package	eSIP-7C
Mounting Type	Through Hole
RoHS Status	RoHS Compliant
MSL Rating	1 (Unlimited)
Product Status	Active

Substitute Part Grouping Explanation

Substitution within the TOPSwitch®-HX family is determined by the following critical parameters:

Fixed Parameters (Must Match for Direct Substitution):

Topology: Flyback
Output Isolation: Isolated
Voltage - Breakdown: 700V
Frequency - Switching: 66kHz, 132kHz
Duty Cycle: 78%
Fault Protection: Current Limiting, Over Temperature, Over Voltage
Operating Temperature Range: -40°C ~ 150°C (TJ)
Package / Case: 7-SSIP, 6 Leads, Exposed Pad, Formed Leads
Supplier Device Package: eSIP-7C
Mounting Type: Through Hole
RoHS Status: RoHS Compliant
MSL Rating: 1 (Unlimited)

Variable Parameter (Determines Power Rating Class):

Power (Watts): Varies by part number within the series

All substitute parts listed maintain identical electrical characteristics, thermal specifications, protection features, and physical packaging. The primary distinction is the maximum power handling capability, which scales across the TOPSwitch®-HX product line.

Parameter Comparison

Part Number	Manufacturer	Series	Power (W)	Topology	Voltage Breakdown	Switching Frequency	Package	Operating Temp	RoHS	Inventory (Pcs)
TOP257EG	Power Integrations	TOPSwitch®-HX	157	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	5200
TOP253EN	Power Integrations	TOPSwitch®-HX	25	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	1177
TOP254EG	Power Integrations	TOPSwitch®-HX	62	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	16400
TOP254EN	Power Integrations	TOPSwitch®-HX	62	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	3834
TOP255EN	Power Integrations	TOPSwitch®-HX	81	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	10037
TOP256EG	Power Integrations	TOPSwitch®-HX	119	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	1266
TOP256EN	Power Integrations	TOPSwitch®-HX	119	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	27159
TOP257EN	Power Integrations	TOPSwitch®-HX	157	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	1436
TOP258EN	Power Integrations	TOPSwitch®-HX	195	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	16620
TOP259EG	Power Integrations	TOPSwitch®-HX	238	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	9200
TOP259EN	Power Integrations	TOPSwitch®-HX	238	Flyback	700V	66kHz, 132kHz	eSIP-7C	-40°C ~ 150°C	Compliant	10100

Engineering Selection Recommendations

Direct Equivalent (Same Power Rating):

TOP257EN is the direct parametric equivalent to TOP257EG. Both devices deliver 157W maximum power with identical electrical specifications, thermal operating range, and package configuration. The distinction between EG and EN suffixes reflects manufacturing date code or internal revision levels. TOP257EN inventory (1436 pcs) is available for applications requiring the same power class as TOP257EG.

Higher Power Capability:

TOP258EN (195W) and TOP259EG/TOP259EN (238W) provide increased power handling within the same package and electrical framework. These parts are suitable for applications where TOP257EG power rating is insufficient, provided circuit design accommodates the higher power delivery capability.

Lower Power Capability:

TOP253EN (25W), TOP254EG/TOP254EN (62W), TOP255EN (81W), and TOP256EG/TOP256EN (119W) operate within the same topology and protection architecture but with reduced maximum power ratings. These parts are suitable for applications with lower power requirements or where thermal constraints necessitate lower power dissipation.

Compliance and Certification:

All substitute parts maintain Active product status, RoHS compliance, REACH unaffected status, and MSL 1 rating. All parts are classified under ECCN EAR99 and HTSUS 8542.39.0001. No additional compliance verification is required when substituting within this family.

Packaging and Mounting:

All listed parts use identical eSIP-7C package configuration with 7-SSIP, 6 leads, exposed pad, and formed leads. Through-hole mounting compatibility is maintained across all substitutes, enabling direct PCB footprint compatibility.

Frequently Asked Questions (FAQ)

Q: Can TOP257EN be used as a direct replacement for TOP257EG?

A: Yes. TOP257EN and TOP257EG are parametric equivalents with identical power rating (157W), electrical specifications, thermal range (-40°C to 150°C), switching frequency (66kHz/132kHz), and eSIP-7C package configuration. Both maintain RoHS compliance and MSL 1 rating.

Q: What is the difference between EG and EN suffix designations?

A: The EG and EN suffixes indicate manufacturing date code or internal revision levels within the same base product number. Both designations represent the same electrical and mechanical specifications for the given power rating.

Q: Can I substitute TOP259EG (238W) for TOP257EG (157W)?

A: TOP259EG operates at higher maximum power output but maintains identical topology, isolation, voltage rating, switching frequency, duty cycle, fault protection, operating temperature range, and package configuration. Substitution is electrically compatible; however, circuit design must accommodate the higher power capability and thermal characteristics of the higher-rated device.

Q: Can I substitute TOP256EN (119W) for TOP257EG (157W)?

A: TOP256EN operates at lower maximum power output. Substitution is not appropriate if the application requires the full 157W power capability of TOP257EG. However, if application power requirements are 119W or lower, TOP256EN provides compatible electrical and mechanical characteristics within the same TOPSwitch®-HX family.

Q: Are all substitute parts compatible with the same PCB footprint?

A: Yes. All listed substitute parts use the eSIP-7C package with 7-SSIP, 6 leads, exposed pad, and formed leads. PCB footprint compatibility is maintained across all substitutes without modification.

Q: What fault protection features are included in all substitute parts?

A: All substitute parts within the TOPSwitch®-HX family include current limiting, over-temperature protection, and over-voltage protection. These protection features are identical across all listed parts regardless of power rating.

Q: Are there any temperature or environmental restrictions for these parts?

A: All substitute parts operate within the same temperature range: -40°C to 150°C junction temperature (TJ). All parts maintain MSL 1 (unlimited moisture sensitivity) rating and are RoHS compliant. No additional environmental restrictions apply beyond standard handling for electronic components.

Q: What switching frequencies are supported by substitute parts?

A: All substitute parts support dual switching frequency operation at 66kHz or 132kHz. Frequency selection is determined by circuit design and transformer configuration, not by part selection within this family.

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