FSQ0365RLX Equivalent & Substitute Parts

Part Overview

The FSQ0365RLX is an offline switch flyback converter IC manufactured by onsemi, designed for isolated power management applications. This Surface Mount Device (SMD) operates in the 55kHz to 67kHz switching frequency range with a maximum power rating of 25W and a 650V breakdown voltage. The part is currently in Active product status with 1415 units in stock.

Substitute parts become necessary when the FSQ0365RLX reaches end-of-life status, when inventory constraints occur, or when design requirements shift toward different power levels or operating characteristics. The parts listed below provide functional equivalence or parametric compatibility based on flyback topology, isolation requirements, and fault protection capabilities.

Substiute Parts

FSQ0365RLX

onsemiIn Stock: 1433FSQ0365RLX Datasheet

Current PartRFQ

NCP11184A100PG

onsemiIn Stock: 7004NCP11184A100PG Datasheet

MFR RecommendedRFQ

FSQ0265RLX

onsemiIn Stock: 24889FSQ0265RLX Datasheet

Parametric EquivalentRFQ

FSQ321LX

onsemiIn Stock: 2145FSQ321LX Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FSQ0365RLX are classified based on the following substitution criteria:

Parametric Equivalents maintain identical or near-identical electrical and mechanical specifications:

• Flyback topology with isolated output
• 650V breakdown voltage
• 8V ~ 20V supply voltage range
• 55kHz ~ 67kHz switching frequency
• 8-LSOP Surface Mount package
• Equivalent fault protection features

Manufacturer Recommended Alternatives provide functional equivalence with allowable deviations in specific parameters:

• Different package type (Through Hole vs. Surface Mount)
• Higher breakdown voltage (800V)
• Different switching frequency (100kHz)
• Higher power rating (40W)
• Extended operating temperature range

The key parameters determining substitution eligibility are: topology (Flyback), isolation requirement (Isolated), package compatibility, mounting type, and fault protection capabilities.

Parameter Comparison

Engineering Selection Recommendations

FSQ0265RLX is a parametric equivalent suitable for designs where power requirements can be reduced to 20W. This part shares identical electrical characteristics with the FSQ0365RLX including topology, voltage ratings, and switching frequency. However, FSQ0265RLX is marked as Obsolete; selection should be limited to legacy design maintenance or when existing inventory is available. Both parts maintain ROHS3 compliance and identical operating temperature ranges.

FSQ321LX is a parametric equivalent for applications requiring 12W maximum power output. This part maintains the same 8-LSOP Surface Mount package, 650V breakdown voltage, and 55kHz ~ 67kHz switching frequency as the FSQ0365RLX. FSQ321LX is also marked as Obsolete and should be selected only for legacy applications or when inventory constraints require lower-power alternatives.

NCP11184A100PG is a manufacturer-recommended alternative from onsemi's mWSaver™ series. This part provides higher power capability (40W) and superior breakdown voltage (800V), making it suitable for designs requiring enhanced performance margins. The NCP11184A100PG operates at 100kHz switching frequency and includes additional fault protection features (Open Loop, Short Circuit). The primary trade-off is the Through Hole mounting type (8-DIP package) versus Surface Mount, requiring PCB layout redesign. This part is Active status with extended operating temperature range (-40°C ~ 150°C TJ). Selection is appropriate for new designs or upgrades where board space permits Through Hole mounting.

Frequently Asked Questions (FAQ)

Q: Can FSQ0265RLX or FSQ321LX be used as direct replacements for FSQ0365RLX?

A: FSQ0265RLX and FSQ321LX are parametric equivalents with identical electrical characteristics (topology, voltage ratings, switching frequency, package type). However, both are marked as Obsolete. Direct substitution is possible if power requirements can be met at 20W (FSQ0265RLX) or 12W (FSQ321LX) respectively. Verify that your application does not exceed these power limits before substitution.

Q: What are the key differences between FSQ0365RLX and NCP11184A100PG?

A: The primary differences are: (1) Package type—NCP11184A100PG uses Through Hole 8-DIP mounting versus Surface Mount 8-LSOP; (2) Switching frequency—100kHz versus 55kHz ~ 67kHz; (3) Power rating—40W versus 25W; (4) Breakdown voltage—800V versus 650V; (5) Fault protection—NCP11184A100PG includes additional Open Loop and Short Circuit protection. NCP11184A100PG is suitable for designs requiring higher power or enhanced protection, but requires PCB redesign for Through Hole mounting.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. FSQ0365RLX, FSQ0265RLX, FSQ321LX, and NCP11184A100PG are all ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

Q: Which substitute part should be selected for new designs?

A: For new designs, NCP11184A100PG is the recommended choice as it is Active status with higher performance specifications (40W power, 800V breakdown voltage, extended temperature range). FSQ0265RLX and FSQ321LX are Obsolete and should be avoided in new designs unless legacy compatibility is required.

Q: Can FSQ0365RLX be used in applications designed for NCP11184A100PG?

A: No. FSQ0365RLX has lower power rating (25W versus 40W), lower breakdown voltage (650V versus 800V), and requires Surface Mount mounting versus Through Hole. Additionally, the switching frequency differs (55kHz ~ 67kHz versus 100kHz). Substitution in the reverse direction requires circuit redesign and validation.

Q: What is the impact of switching frequency differences on substitution?

A: Switching frequency affects transformer design, output filtering, and EMI characteristics. FSQ0365RLX, FSQ0265RLX, and FSQ321LX operate at 55kHz ~ 67kHz, while NCP11184A100PG operates at 100kHz. Higher switching frequency typically allows smaller transformer and filter components but may increase switching losses. Substitution between different frequency ranges requires transformer and filter redesign.