TOP261LG Equivalent & Substitute Parts

Part Overview

The TOP261LG is an offline switch flyback converter IC manufactured by Power Integrations, part of the TOPSwitch®-HX series. This component operates at 66kHz or 132kHz switching frequency with a 700V breakdown voltage rating and delivers 244W output power. The device integrates internal switching functionality with comprehensive fault protection including current limiting, over-temperature, and over-voltage protection.

The TOP261LG is classified as obsolete. Equivalent and substitute parts from the active TOPSwitch®-HX product line provide direct functional alternatives while maintaining design compatibility within the specified electrical and mechanical parameters.

Key Parameters

Parameter	Value
Manufacturer	Power Integrations
Series	TOPSwitch®-HX
Topology	Flyback
Voltage - Breakdown	700V
Frequency - Switching	66kHz, 132kHz
Duty Cycle	78%
Output Isolation	Isolated
Internal Switch(s)	Yes
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
Mounting Type	Through Hole
RoHS Status	RoHS Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

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

Fixed Parameters (Must Match):

Topology: Flyback
Voltage - Breakdown: 700V
Frequency - Switching: 66kHz, 132kHz
Duty Cycle: 78%
Output Isolation: Isolated
Internal Switch(s): Yes
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
Mounting Type: Through Hole
RoHS Status: RoHS Compliant
Moisture Sensitivity Level (MSL): 1 (Unlimited)

Variable Parameter (Determines Power Rating):

Power (Watts): Ranges from 21W to 244W across the TOPSwitch®-HX family

All substitute parts listed maintain identical electrical characteristics, protection features, and mechanical compatibility. Selection is based on power rating requirements for the specific application circuit.

Parameter Comparison

Part Number	Manufacturer	Power (W)	Voltage Breakdown (V)	Switching Frequency (kHz)	Duty Cycle (%)	Operating Temp (°C)	Product Status	Inventory (Pcs)
TOP261LG	Power Integrations	244	700	66, 132	78	-40 ~ 150	Obsolete	933
TOP252EG	Power Integrations	21	700	66, 132	78	-40 ~ 150	Active	696
TOP252EN	Power Integrations	21	700	66, 132	78	-40 ~ 150	Active	5100
TOP253EG	Power Integrations	43	700	66, 132	78	-40 ~ 150	Active	677
TOP253EN	Power Integrations	25	700	66, 132	78	-40 ~ 150	Active	1177
TOP254EG	Power Integrations	62	700	66, 132	78	-40 ~ 150	Active	16400
TOP254EN	Power Integrations	62	700	66, 132	78	-40 ~ 150	Active	3834
TOP255EG	Power Integrations	81	700	66, 132	78	-40 ~ 150	Active	8000
TOP255EN	Power Integrations	81	700	66, 132	78	-40 ~ 150	Active	10037
TOP256EG	Power Integrations	119	700	66, 132	78	-40 ~ 150	Active	1266
TOP256EN	Power Integrations	119	700	66, 132	78	-40 ~ 150	Active	27159

Engineering Selection Recommendations

Product Status Consideration: The TOP261LG is classified as obsolete. All listed substitute parts are active products with ongoing manufacturing and support from Power Integrations. Selection of active alternatives ensures long-term supply chain stability and access to technical documentation.

Compliance and Certifications: All substitute parts maintain identical compliance status:

RoHS Compliant
REACH Unaffected
ECCN: EAR99
HTSUS: 8542.39.0001
Moisture Sensitivity Level (MSL): 1 (Unlimited)

Power Rating Selection: The TOP261LG delivers 244W. No direct 244W equivalent exists in the active product line. For applications requiring the highest available power rating within the TOPSwitch®-HX family, TOP256EG or TOP256EN (119W) represent the maximum active offering. Applications with lower power requirements should select the appropriate substitute based on actual circuit power demands.

Packaging and Mounting: All substitute parts use identical 7-SSIP through-hole packaging with exposed pad and formed leads, ensuring direct mechanical compatibility with existing PCB layouts designed for TOP261LG.

Frequently Asked Questions (FAQ)

Q: Can TOP256EN directly replace TOP261LG in my circuit?

A: TOP256EN shares all electrical characteristics, protection features, and mechanical compatibility with TOP261LG. However, TOP256EN is rated for 119W output power while TOP261LG is rated for 244W. Direct substitution is valid only if your circuit operates at or below 119W power levels. Exceeding this rating violates the component's electrical specifications.

Q: What is the difference between TOP256EG and TOP256EN?

A: Both parts are identical in electrical specifications and power rating (119W). The difference is in packaging format: EG uses tube packaging while EN uses tube packaging. Both are active products with equivalent availability and compliance status.

Q: Why are there no active products rated at 244W in the TOPSwitch®-HX family?

A: The provided data includes only the substitute parts listed in the input parameters. The TOP261LG 244W rating represents a higher power tier within the TOPSwitch®-HX series. Substitution must be based on available active alternatives.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed maintain RoHS Compliant status, identical to the TOP261LG. REACH status is also identical (REACH Unaffected) across all parts.

Q: Can I use TOP254EN instead of TOP254EG?

A: Yes. Both TOP254EN and TOP254EG deliver 62W output power with identical electrical specifications and mechanical compatibility. Selection between them depends on packaging preference and inventory availability. TOP254EN has higher inventory (3834 pcs vs 16400 pcs for TOP254EG).

Q: What is the operating temperature range for all substitute parts?

A: All substitute parts operate across -40°C to 150°C junction temperature (TJ), matching the TOP261LG specification.

Q: Are the switching frequency options the same across all parts?

A: Yes. All parts in the TOPSwitch®-HX family listed here support dual switching frequency operation at 66kHz or 132kHz, with 78% duty cycle maintained across all models.

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