TOP253PNAU Equivalent & Substitute Parts Reference

Part Overview

The TOP253PNAU is an offline switch flyback converter IC from Power Integrations' TOPSwitch®-HX series, designed for isolated power supply applications. This component operates at 66 kHz switching frequency with 25 W power output capability and integrates internal current limiting, over-temperature, and over-voltage protection. The TOP253PNAU is classified as obsolete; however, direct and parametric equivalents remain available in active production status, ensuring design continuity and supply chain reliability for existing applications requiring replacement or redesign.

Key Parameters

Parameter	Value
Manufacturer	Power Integrations
Series	TOPSwitch®-HX
Topology	Flyback
Output Isolation	Isolated
Voltage - Breakdown	700V
Frequency - Switching	66 kHz
Duty Cycle	78%
Power (Watts)	25 W
Fault Protection	Current Limiting, Over Temperature, Over Voltage
Operating Temperature Range	-40°C to 150°C (TJ)
Package / Case	8-DIP (0.300", 7.62mm), 7 Leads
Supplier Device Package	8-PDIP-C
Mounting Type	Through Hole
Moisture Sensitivity Level (MSL)	1 (Unlimited)
REACH Status	REACH Unaffected
ECCN	EAR99
HTSUS Code	8542.39.0001

Substitute Part Grouping Explanation

Substitution of the TOP253PNAU is determined by strict adherence to the following critical parameters:

Direct Substitutes (Identical Electrical and Mechanical Specifications): Parts that maintain 700V breakdown voltage, 66 kHz switching frequency, 78% duty cycle, 25 W power output, isolated topology, and 8-DIP package are classified as direct substitutes. These parts differ only in product status (active vs. obsolete) or packaging format (tube vs. standard).

Parametric Equivalents (Same Core Architecture, Different Power Rating): Parts within the TOPSwitch®-HX series sharing identical voltage, frequency, duty cycle, topology, package, and protection features but with different power ratings (15 W, 28 W, 30 W, 34 W, 41 W) are classified as parametric equivalents. These maintain full electrical and mechanical compatibility while offering alternative power handling capabilities.

Key Substitution Criteria:

Voltage - Breakdown: 700V (mandatory)
Topology: Flyback (mandatory)
Output Isolation: Isolated (mandatory)
Frequency - Switching: 66 kHz (mandatory)
Duty Cycle: 78% (mandatory)
Package / Case: 8-DIP (0.300", 7.62mm), 7 Leads (mandatory)
Fault Protection: Current Limiting, Over Temperature, Over Voltage (mandatory)
Operating Temperature Range: -40°C to 150°C (mandatory)

Parameter Comparison

Part Number	Manufacturer	Product Status	Power (W)	Voltage Breakdown (V)	Frequency (kHz)	Duty Cycle (%)	Package	RoHS Status	Inventory (Pcs)
TOP253PNAU	Power Integrations	Obsolete	25	700	66	78	8-DIP	Not Specified	1,171
TOP253PN	Power Integrations	Active	25	700	66	78	8-DIP	RoHS Compliant	35,300
TOP253PG	Power Integrations	Active	25	700	66	78	8-DIP	RoHS Compliant	1,025
TOP252PN	Power Integrations	Active	15	700	66	78	8-DIP	RoHS Compliant	16,771
TOP252PG	Power Integrations	Active	15	700	66	78	8-DIP	RoHS Compliant	968
TOP254PN	Power Integrations	Active	28	700	66	78	8-DIP	RoHS Compliant	20,300
TOP254PG	Power Integrations	Active	28	700	66	78	8-DIP	RoHS Compliant	842
TOP255PN	Power Integrations	Active	30	700	66	78	8-DIP	RoHS Compliant	5,619
TOP256PN	Power Integrations	Active	34	700	66	78	8-DIP	RoHS Compliant	19,116
TOP257PN	Power Integrations	Active	41	700	66	78	8-DIP	RoHS Compliant	1,308
TOP257PG	Power Integrations	Active	41	700	66	78	8-DIP	RoHS Compliant	1,057

Engineering Selection Recommendations

Direct Replacement (Same Power Rating - 25 W):

TOP253PN is the primary direct replacement for TOP253PNAU. Both parts maintain identical electrical specifications (700V breakdown, 66 kHz switching, 78% duty cycle, 25 W output) and mechanical compatibility (8-DIP package). TOP253PN carries active product status and RoHS compliance certification, with significantly higher inventory availability (35,300 units). The suffix change from "AU" to "PN" indicates packaging format transition from standard to tube packaging, with no functional impact on circuit performance.

TOP253PG provides an alternative direct replacement with identical specifications and active status. Inventory levels are lower (1,025 units), making TOP253PN the preferred selection for new designs and high-volume applications.

Parametric Equivalents (Alternative Power Ratings):

For applications requiring higher power handling within the same architecture:

TOP254PN/PG: 28 W output (3 W increase)
TOP255PN: 30 W output (5 W increase)
TOP256PN: 34 W output (9 W increase)
TOP257PN/PG: 41 W output (16 W increase)

For applications with lower power requirements:

TOP252PN/PG: 15 W output (10 W reduction)

All parametric equivalents maintain 700V breakdown voltage, 66 kHz switching frequency, 78% duty cycle, isolated topology, 8-DIP package configuration, and identical protection features. Selection of parametric equivalents requires verification that the application's power budget aligns with the substitute part's rated output.

Compliance and Certification:

All active substitute parts carry RoHS compliance certification. The TOP253PNAU (obsolete) does not specify RoHS status. For applications subject to RoHS requirements, TOP253PN or TOP253PG are mandatory selections. All parts maintain REACH Unaffected status and EAR99 export classification.

Frequently Asked Questions (FAQ)

Q: Can TOP253PN directly replace TOP253PNAU without circuit modifications?

A: Yes. TOP253PN is a direct functional equivalent with identical electrical specifications (700V breakdown, 66 kHz switching, 78% duty cycle, 25 W power output) and mechanical compatibility (8-DIP package, 7 leads, through-hole mounting). The suffix change reflects packaging format only (tube vs. standard). No circuit redesign is required.

Q: What is the difference between TOP253PN and TOP253PG?

A: Both parts are electrically and mechanically identical with 25 W power output. The suffix difference (PN vs. PG) indicates packaging format variation. TOP253PN uses tube packaging; TOP253PG uses alternative packaging. Selection depends on assembly equipment compatibility and procurement preferences. Both are active products with RoHS compliance.

Q: Can I use TOP254PN (28 W) in place of TOP253PNAU (25 W)?

A: TOP254PN maintains all core electrical and mechanical parameters (700V breakdown, 66 kHz switching, 78% duty cycle, 8-DIP package, isolated topology, identical protection features). The 3 W power rating increase does not create incompatibility. However, this substitution is classified as parametric equivalent rather than direct replacement. Verify that the application's transformer and output stage design can accommodate the higher power capability without thermal or component stress.

Q: Is TOP252PN (15 W) suitable as a substitute for TOP253PNAU (25 W)?

A: TOP252PN maintains identical electrical architecture and mechanical compatibility but with 10 W lower power output. This substitution is only appropriate for applications where the 15 W rating meets the power budget requirement. Using a lower-rated part in a 25 W application will result in insufficient power delivery and potential circuit malfunction. Verify application power requirements before selection.

Q: Why is TOP253PNAU classified as obsolete?

A: TOP253PNAU is obsolete due to product lifecycle management by Power Integrations. Direct replacements (TOP253PN, TOP253PG) are available in active production with identical specifications and improved compliance certifications (RoHS). Existing inventory of TOP253PNAU remains available (1,171 units), but new designs should specify active alternatives.

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

A: Yes. All substitute parts use 8-DIP (0.300", 7.62mm) package with 7 leads and through-hole mounting. PCB footprints are identical across all listed substitutes. No layout modifications are required when switching between direct or parametric equivalents.

Q: What is the impact of switching from TOP253PNAU to an active RoHS-compliant part?

A: RoHS compliance certification ensures the substitute part meets restricted substance limits for lead, cadmium, mercury, hexavalent chromium, and flame retardants. This is mandatory for applications subject to RoHS regulations (EU, California, and other jurisdictions). TOP253PN and TOP253PG carry explicit RoHS Compliant certification, while TOP253PNAU does not specify compliance status. For regulated applications, active RoHS-compliant parts are required.

Q: Can parametric equivalents with higher power ratings be used in lower-power applications?

A: Yes. A higher-rated part (e.g., TOP256PN at 34 W) can operate in a 25 W application without functional degradation. The part will operate below its maximum rating, resulting in lower thermal stress and extended component life. However, circuit design must accommodate the part's electrical characteristics. Verify that transformer turns ratios, feedback networks, and output filtering are compatible with the substitute part's specifications.

Q: What inventory considerations should guide part selection?

A: TOP253PN offers the highest inventory availability (35,300 units) for direct replacement applications, ensuring supply chain reliability. TOP253PG (1,025 units) provides an alternative direct replacement with lower availability. Parametric equivalents show varying inventory levels: TOP254PN (20,300), TOP256PN (19,116), TOP252PN (16,771), TOP255PN (5,619), TOP257PN (1,308), and TOP257PG (1,057). For high-volume production, TOP253PN is the preferred selection. For lower-volume applications, alternative direct replacements or parametric equivalents may be selected based on availability and power requirements.

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