FQB4N50TM Equivalent & Substitute Parts

Part Overview

The FQB4N50TM is an N-Channel MOSFET manufactured by onsemi, rated for 500V drain-to-source voltage with a continuous drain current of 3.4A at 25°C. The device is housed in a TO-263 (D2PAK) surface mount package and is part of the QFET® series. This part is currently classified as obsolete, making identification of equivalent and substitute components essential for ongoing design support, maintenance, and production continuity.

Substiute Parts

FQB4N50TM

onsemiIn Stock: 1246FQB4N50TM Datasheet

Current PartRFQ

IRF820STRRPBF

Vishay SiliconixIn Stock: 2577IRF820STRRPBF Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FQB4N50TM is determined by strict alignment of the following critical electrical and mechanical parameters:

Voltage Rating: The substitute must maintain the 500V Vdss specification to ensure safe operation in the same circuit topology without risk of breakdown.

Package Type: The TO-263 (D2PAK) surface mount package is mandatory for mechanical and thermal compatibility with existing PCB layouts and assembly processes.

FET Type and Technology: N-Channel MOSFET (Metal Oxide) technology ensures functional equivalence in switching and amplification applications.

Operating Temperature Range: The -55°C to 150°C junction temperature range must be maintained to support the same environmental and thermal operating conditions.

Current Rating: While the substitute may have a lower continuous drain current rating, it must be capable of supporting the application's actual current requirements without exceeding its thermal limits.

On-State Resistance and Gate Characteristics: These parameters determine switching performance and drive requirements. Substitutes with comparable or superior specifications maintain circuit performance.

The IRF820STRRPBF from Vishay Siliconix qualifies as a substitute based on matching voltage rating, package type, FET technology, and operating temperature range, despite differences in current rating and secondary electrical characteristics.

Parameter Comparison

Engineering Selection Recommendations

Product Status Consideration: The FQB4N50TM is classified as obsolete. The IRF820STRRPBF is classified as active, ensuring ongoing availability and manufacturing support from Vishay Siliconix.

Compliance and Certifications: The IRF820STRRPBF carries RoHS3 compliance certification, meeting current environmental and regulatory standards. Both devices are classified as EAR99 for export control purposes and carry identical HTSUS codes, indicating equivalent trade classification.

Substitution Validity: The IRF820STRRPBF is a valid substitute for the FQB4N50TM in applications where the continuous drain current requirement does not exceed 2.5A. The matching 500V voltage rating, identical package type, and overlapping operating temperature range ensure mechanical and electrical compatibility.

Current Rating Limitation: Applications requiring continuous drain currents above 2.5A at 25°C cannot use the IRF820STRRPBF as a direct substitute. In such cases, alternative 500V N-Channel MOSFETs with higher current ratings in TO-263 packaging must be evaluated.

Secondary Parameter Differences: The IRF820STRRPBF exhibits higher gate charge (24 nC vs. 13 nC) and lower maximum gate voltage (±20V vs. ±30V). These differences may affect gate drive circuit design and switching speed characteristics. Thermal performance is also reduced (50W Tc vs. 70W Tc), requiring thermal management verification in high-power applications.

Frequently Asked Questions (FAQ)

Q: Can the IRF820STRRPBF replace the FQB4N50TM in all applications?

A: The IRF820STRRPBF is a valid substitute only in applications where the continuous drain current requirement does not exceed 2.5A at 25°C. If your application requires higher current handling, alternative substitutes must be evaluated.

Q: Why is the continuous drain current different between these two parts?

A: The IRF820STRRPBF has a lower continuous drain current rating (2.5A vs. 3.4A) due to differences in die design and thermal characteristics between manufacturers. This is a fundamental specification difference and not a performance variation.

Q: Are the packages identical?

A: Yes. Both the FQB4N50TM and IRF820STRRPBF use the TO-263 (D2PAK) surface mount package with 2 leads plus tab. They are mechanically and thermally compatible for PCB mounting and assembly.

Q: What is the significance of the gate charge difference?

A: The IRF820STRRPBF has higher gate charge (24 nC vs. 13 nC at 10V). This affects the gate drive circuit design and switching speed. Higher gate charge requires more drive current or longer switching times, which may impact circuit performance in high-frequency applications.

Q: Does the lower maximum gate voltage of the IRF820STRRPBF affect compatibility?

A: The IRF820STRRPBF has a maximum gate voltage rating of ±20V compared to ±30V for the FQB4N50TM. If your gate drive circuit applies voltages exceeding ±20V, the IRF820STRRPBF cannot be used. Standard gate drive circuits typically operate within ±15V, making this difference non-critical for most applications.

Q: What is the thermal performance difference?

A: The FQB4N50TM supports 70W power dissipation at case temperature (Tc), while the IRF820STRRPBF supports 50W. In high-power applications, the IRF820STRRPBF may require additional thermal management or derating to maintain safe junction temperatures.

Q: Is the IRF820STRRPBF RoHS compliant?

A: Yes. The IRF820STRRPBF is RoHS3 compliant, meeting current environmental regulations. The FQB4N50TM's RoHS status is not specified in the provided data.

Q: Can I use the IRF820STRRPBF in a design originally specified for the FQB4N50TM?

A: Yes, provided that the application's continuous drain current requirement does not exceed 2.5A and the gate drive circuit operates within ±20V. Verify thermal performance requirements and gate charge compatibility with your specific circuit design.