FDA18N50 Equivalent & Substitute Parts

Part Overview

The FDA18N50 is an N-Channel MOSFET manufactured by onsemi, rated for 500V drain-to-source voltage with 19A continuous drain current at 25°C. This device is packaged in a TO-3PN through-hole configuration and is part of the UniFET™ series. The FDA18N50 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and component procurement.

Substiute Parts

FDA18N50

onsemiIn Stock: 22216FDA18N50 Datasheet

Current PartRFQ

NTHL185N60S5H

onsemiIn Stock: 799NTHL185N60S5H Datasheet

MFR RecommendedRFQ

IXTQ26N50P

IXYSIn Stock: 5376IXTQ26N50P Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FDA18N50 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

• Drain to Source Voltage (Vdss) must equal or exceed 500V
• Continuous drain current (Id) must meet or exceed 19A at 25°C
• On-state resistance (Rds On) must not significantly degrade circuit performance
• Gate charge (Qg) and input capacitance (Ciss) must be compatible with gate drive circuitry
• Gate threshold voltage (Vgs(th)) and maximum gate voltage (Vgs Max) must align with control electronics
• Operating temperature range must encompass -55°C to 150°C

Mechanical Compatibility Criteria:

• Mounting type must be through-hole
• Package footprint must be compatible with TO-3P or equivalent pinout configurations

Two substitute parts are identified based on these criteria:

1. NTHL185N60S5H (onsemi SuperFET® III) — Manufacturer-recommended substitute with higher voltage rating (600V) and improved on-state resistance characteristics
2. IXTQ26N50P (IXYS Polar) — Similar voltage rating (500V) with enhanced current capability (26A) and power dissipation (400W)

Parameter Comparison

Engineering Selection Recommendations

NTHL185N60S5H Selection Criteria:

The NTHL185N60S5H is the manufacturer-recommended substitute from onsemi. This part maintains N-Channel MOSFET topology with identical gate voltage specifications (±30V maximum). The 600V Vdss rating provides enhanced voltage margin over the 500V FDA18N50 requirement. However, the continuous drain current is reduced to 15A, which is below the FDA18N50 specification of 19A. The on-state resistance is improved at 185 mOhm, and gate charge is significantly reduced to 25 nC, indicating faster switching characteristics. The NTHL185N60S5H is classified as "Not For New Designs," indicating limited long-term availability. The package is TO-247-3, which differs from the FDA18N50 TO-3PN footprint and requires PCB layout modification. RoHS3 compliance and REACH unaffected status are maintained.

IXTQ26N50P Selection Criteria:

The IXTQ26N50P from IXYS provides direct voltage compatibility at 500V Vdss and exceeds the current requirement with 26A continuous drain current. The on-state resistance of 230 mOhm is comparable to the FDA18N50 at 265 mOhm. Power dissipation capability is significantly higher at 400W versus 239W. Gate charge is slightly elevated at 65 nC. The IXTQ26N50P maintains the TO-3P package footprint compatible with the FDA18N50 TO-3P-3 configuration, minimizing PCB redesign. Product status is Active, ensuring ongoing availability and long-term supply continuity. RoHS3 compliance and REACH unaffected status are maintained. Moisture sensitivity level is rated at 1 (Unlimited).

Recommendation Summary:

For applications requiring direct footprint compatibility and long-term component availability, the IXTQ26N50P is the preferred substitute. For applications where voltage margin and switching speed are prioritized over current capacity, the NTHL185N60S5H is suitable, provided PCB layout modifications for TO-247-3 packaging are acceptable.

Frequently Asked Questions (FAQ)

Q: Can the NTHL185N60S5H directly replace the FDA18N50 without PCB modifications?

A: No. The NTHL185N60S5H uses TO-247-3 packaging, while the FDA18N50 uses TO-3PN packaging. These packages have different pinout configurations and thermal characteristics. PCB layout modifications are required, including changes to pad geometry, spacing, and thermal management provisions.

Q: What is the primary limitation of the NTHL185N60S5H as a substitute?

A: The continuous drain current rating of 15A is below the FDA18N50 specification of 19A. Applications requiring the full 19A current capacity cannot use this substitute without circuit redesign to reduce current demand.

Q: Why is the IXTQ26N50P considered a suitable substitute despite being from a different manufacturer?

A: The IXTQ26N50P meets all critical electrical parameters: 500V Vdss matches the FDA18N50 requirement, 26A continuous drain current exceeds the 19A specification, and on-state resistance of 230 mOhm is comparable to 265 mOhm. The TO-3P package is mechanically compatible with the FDA18N50 TO-3P-3 footprint, and the part is in Active product status, ensuring supply continuity.

Q: What is the significance of the "Not For New Designs" status of the NTHL185N60S5H?

A: This status indicates that onsemi is not recommending this part for new circuit designs and may discontinue production. While the part is currently available, long-term supply cannot be guaranteed. The IXTQ26N50P, with Active status, is more suitable for designs requiring extended component availability.

Q: How do gate charge differences affect circuit performance?

A: Gate charge (Qg) determines the energy required to switch the MOSFET on and off. The FDA18N50 requires 60 nC, the NTHL185N60S5H requires 25 nC, and the IXTQ26N50P requires 65 nC. Lower gate charge reduces switching losses and allows faster switching speeds. Gate drive circuitry must supply sufficient current to deliver the required charge within the desired switching time. Substitutes with significantly different gate charge may require gate driver circuit adjustments.

Q: Are there thermal management differences between these parts?

A: Yes. The FDA18N50 has a maximum power dissipation of 239W, the NTHL185N60S5H has 116W, and the IXTQ26N50P has 400W. These ratings reflect the thermal capability of each package and die design. Applications operating near maximum power dissipation must ensure adequate heatsinking. The TO-247-3 package (NTHL185N60S5H) and TO-3P package (IXTQ26N50P) have different thermal resistance characteristics and may require different heatsink designs.

Q: Can both substitutes operate across the full -55°C to 150°C temperature range?

A: Yes. Both the NTHL185N60S5H and IXTQ26N50P specify operating temperature ranges of -55°C to 150°C (TJ), matching the FDA18N50 specification. All three parts are suitable for applications requiring this full temperature range.

Q: What compliance certifications are maintained across all three parts?

A: All three parts—FDA18N50, NTHL185N60S5H, and IXTQ26N50P—are RoHS3 compliant and REACH unaffected. ECCN classification is EAR99 for all parts, and HTSUS code is 8541.29.0095. These certifications ensure regulatory compliance for industrial and commercial applications.