FDB8445 N-Channel MOSFET 40V 70A Equivalent & Substitute Parts

Part Overview

The FDB8445 is an N-Channel MOSFET manufactured by onsemi, rated for 40V drain-to-source voltage with 70A continuous drain current at 25°C. The device is housed in a TO-263 (D2PAK) surface mount package and is designed for high-current switching applications with a maximum power dissipation of 92W at the case temperature.

The FDB8445 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this component.

Substiute Parts

FDB8445

onsemiIn Stock: 2917FDB8445 Datasheet

Current PartRFQ

AOB4184

Alpha & Omega Semiconductor Inc.In Stock: 22678AOB4184 Datasheet

SimilarRFQ

BUK764R0-55B,118

Nexperia USA Inc.In Stock: 7480BUK764R0-55B,118 Datasheet

SimilarRFQ

BUK768R1-40E,118

Nexperia USA Inc.In Stock: 5689BUK768R1-40E,118 Datasheet

SimilarRFQ

PHB191NQ06LT,118

Nexperia USA Inc.In Stock: 3710PHB191NQ06LT,118 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the FDB8445 is determined by the following critical parameters:

Voltage Rating (Vdss): The substitute must support a minimum of 40V drain-to-source voltage. Parts rated at higher voltages (55V) are acceptable as they provide backward compatibility.

Current Rating (Id): The substitute must support a minimum continuous drain current of 70A at 25°C case temperature. Parts rated at 75A or higher satisfy this requirement.

Package Type: All substitutes must use the TO-263 (D2PAK) surface mount package to ensure mechanical and thermal compatibility with existing PCB layouts.

On-Resistance (Rds On): The substitute should maintain comparable on-resistance characteristics at the specified gate voltage (10V) to preserve circuit performance and thermal behavior.

Operating Temperature Range: All substitutes must support the full operating temperature range of -55°C to 175°C (TJ).

Compliance: All substitutes must maintain ROHS3 compliance and equivalent regulatory status (REACH Unaffected, EAR99 classification).

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: BUK768R1-40E,118

The BUK768R1-40E,118 manufactured by Nexperia USA Inc. is the most direct substitute for the FDB8445. This part maintains the identical 40V voltage rating and supports 75A continuous drain current, exceeding the FDB8445 requirement of 70A. The on-resistance of 7.2 mOhm at 10V is comparable to the FDB8445 specification of 9 mOhm, ensuring similar thermal performance. The device is housed in the D2PAK package, providing mechanical compatibility with existing designs. The BUK768R1-40E,118 carries active product status, ensuring long-term availability and supply chain support. It is AEC-Q101 qualified for automotive applications and maintains full ROHS3 compliance.

Secondary Substitute: BUK764R0-55B,118

The BUK764R0-55B,118 is an alternative substitute offering a higher 55V voltage rating with 75A continuous drain current capability. This part provides enhanced voltage margin for applications requiring additional headroom. The on-resistance of 4 mOhm at 10V is superior to the FDB8445, resulting in lower power dissipation and improved thermal characteristics. The maximum power dissipation of 300W (Tc) significantly exceeds the FDB8445 specification of 92W, providing thermal design flexibility. This device is AEC-Q101 qualified and maintains active product status with full ROHS3 compliance.

Tertiary Substitute: PHB191NQ06LT,118

The PHB191NQ06LT,118 is a high-performance alternative with a 55V voltage rating and 75A continuous drain current. This part features the lowest on-resistance of 3.7 mOhm at 10V among all substitutes, delivering superior efficiency and thermal performance. The maximum power dissipation of 300W (Tc) provides significant thermal margin. This device maintains active product status and full ROHS3 compliance. Note that the maximum gate voltage specification is ±15V compared to the FDB8445 specification of ±20V.

Not Recommended: AOB4184

The AOB4184 manufactured by Alpha & Omega Semiconductor Inc. does not meet the continuous drain current requirement. While rated at 50A (Tc), this falls below the FDB8445 specification of 70A. Although the device maintains the 40V voltage rating and D2PAK package compatibility, the reduced current rating makes it unsuitable for direct substitution in applications requiring the full 70A capability.

Frequently Asked Questions (FAQ)

Q: Can the BUK768R1-40E,118 be used as a direct replacement for the FDB8445?

A: Yes. The BUK768R1-40E,118 maintains the same 40V voltage rating and supports 75A continuous drain current, exceeding the FDB8445 requirement of 70A. Both devices use the D2PAK package and operate across the same temperature range (-55°C to 175°C). The on-resistance characteristics are comparable, ensuring similar circuit performance.

Q: What is the advantage of using BUK764R0-55B,118 or PHB191NQ06LT,118 over BUK768R1-40E,118?

A: Both BUK764R0-55B,118 and PHB191NQ06LT,118 offer higher voltage ratings (55V) and superior on-resistance characteristics. The higher voltage rating provides additional design margin for transient overvoltage conditions. The lower on-resistance reduces power dissipation and heat generation, which may be beneficial in thermally constrained applications. However, these advantages come with increased gate charge and input capacitance, which may affect switching speed and driver requirements.

Q: Are all substitute parts available in the same packaging format?

A: Yes. All substitute parts are housed in the TO-263 (D2PAK) surface mount package, ensuring mechanical and thermal compatibility with existing PCB layouts. No modifications to board design or thermal management are required.

Q: What is the significance of the AEC-Q101 qualification on the Nexperia parts?

A: AEC-Q101 qualification indicates that the parts meet automotive-grade reliability and quality standards established by the Automotive Electronics Council. This qualification is relevant for applications requiring automotive-grade components. The FDB8445 does not carry this designation.

Q: Why is the AOB4184 not recommended as a substitute?

A: The AOB4184 is rated for a maximum continuous drain current of 50A at 25°C case temperature, which is below the FDB8445 specification of 70A. Using this part in applications requiring the full 70A capability would result in thermal stress and potential device failure. The part is suitable only for applications with reduced current requirements.

Q: How do gate charge differences affect circuit design?

A: Gate charge (Qg) determines the amount of charge required to switch the MOSFET on and off. The FDB8445 specifies 62 nC at 10V. Substitute parts vary from 24 nC (BUK768R1-40E,118) to 95.6 nC (PHB191NQ06LT,118). Lower gate charge enables faster switching and reduces driver power dissipation. Higher gate charge may require driver optimization but does not prevent substitution in most applications.

Q: Are there thermal performance differences between substitutes?

A: Yes. The on-resistance (Rds On) directly affects power dissipation and thermal performance. The FDB8445 specifies 9 mOhm at 70A and 10V. BUK768R1-40E,118 offers 7.2 mOhm, while BUK764R0-55B,118 and PHB191NQ06LT,118 offer 4 mOhm and 3.7 mOhm respectively. Lower on-resistance results in reduced power dissipation and lower junction temperatures, improving reliability and allowing for higher ambient operating conditions.

Q: What compliance certifications apply to all substitute parts?

A: All substitute parts maintain ROHS3 compliance, REACH Unaffected status, and EAR99 export classification, matching the regulatory profile of the FDB8445. These certifications ensure compatibility with environmental and export regulations applicable to the original part.