FDB8447L N-Channel MOSFET 40V 15A/50A TO-263 Equivalent & Substitute Parts

Part Overview

The FDB8447L is an N-Channel MOSFET manufactured by onsemi, rated for 40V drain-to-source voltage with continuous drain current of 15A at Ta (ambient temperature) and 50A at Tc (case temperature). The device is housed in a TO-263 (D2PAK) surface mount package and is part of the PowerTrench® series. The FDB8447L is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. Substitute parts must maintain compatibility with the TO-263 package footprint and deliver equivalent electrical performance within the specified voltage and current ratings.

Key Parameters

Parameter	FDB8447L Value	Unit
Drain-to-Source Voltage (Vdss)	40	V
Continuous Drain Current @ 25°C (Ta)	15	A
Continuous Drain Current @ 25°C (Tc)	50	A
RDS(on) Max @ Id, Vgs	8.5 mOhm @ 14A, 10V	mOhm
Gate Threshold Voltage (Vgs(th)) Max @ Id	3	V @ 250µA
Gate Charge (Qg) Max @ Vgs	52	nC @ 10V
Input Capacitance (Ciss) Max @ Vds	2620	pF @ 20V
Power Dissipation Max (Ta)	3.1	W
Power Dissipation Max (Tc)	60	W
Operating Temperature Range	-55 to 150	°C (TJ)
Package Type	TO-263 (D2PAK)	Surface Mount
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitute parts for the FDB8447L are evaluated based on the following critical parameters that determine functional equivalence:

Primary Matching Criteria:

Drain-to-Source Voltage (Vdss): Must equal or exceed 40V
Package Type: Must be TO-263 (D2PAK) or compatible surface mount package
Continuous Drain Current (Tc): Must support 50A at case temperature
RDS(on) Performance: Must deliver comparable on-resistance characteristics
Gate Threshold Voltage: Must fall within acceptable switching range
Operating Temperature Range: Must support -55°C to 150°C minimum

Substitution Logic: Parts are grouped into two categories based on voltage rating alignment:

Direct Voltage Equivalents (40V Rating): AOB4184 and STB170NF04 maintain the 40V Vdss specification, ensuring direct compatibility with circuits designed for the FDB8447L voltage class.
Higher Voltage Alternatives (55V Rating): BUK764R0-55B,118 and PHB191NQ06LT,118 provide 55V Vdss ratings, offering enhanced voltage margin for applications requiring additional headroom while maintaining TO-263 package compatibility.
Lower Voltage Alternative (30V Rating): TSM085N03PQ33 RGG operates at 30V Vdss with a different package format (8-PDFN), suitable only for applications with reduced voltage requirements and where package footprint changes are acceptable.

Parameter Comparison

Parameter	FDB8447L	AOB4184	STB170NF04	BUK764R0-55B,118	PHB191NQ06LT,118	TSM085N03PQ33 RGG
Manufacturer	onsemi	Alpha & Omega Semiconductor Inc.	STMicroelectronics	Nexperia USA Inc.	Nexperia USA Inc.	Taiwan Semiconductor Corporation
Vdss (V)	40	40	40	55	55	30
Id @ 25°C Ta (A)	15	12	-	-	-	-
Id @ 25°C Tc (A)	50	50	80	75	75	52
RDS(on) Max (mOhm)	8.5 @ 14A, 10V	10 @ 20A, 10V	5 @ 40A, 10V	4 @ 25A, 10V	3.7 @ 25A, 10V	8.5 @ 13A, 10V
Vgs(th) Max (V)	3 @ 250µA	3 @ 250µA	4 @ 250µA	4 @ 1mA	2 @ 1mA	2.5 @ 250µA
Qg Max (nC)	52 @ 10V	35 @ 10V	170 @ 10V	86 @ 10V	95.6 @ 5V	14.3 @ 10V
Ciss Max (pF)	2620 @ 20V	1800 @ 20V	9000 @ 25V	6776 @ 25V	7665 @ 25V	817 @ 15V
Power Dissipation Max Tc (W)	60	50	300	300	300	37
Operating Temperature (°C)	-55 to 150	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 150
Package Type	TO-263 (D2PAK)	TO-263 (D2PAK)	TO-263 (D2PAK)	D2PAK	D2PAK	8-PDFN (3.1x3.1)
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (40V Voltage Class, TO-263 Package):

AOB4184 (Alpha & Omega Semiconductor Inc.) is the primary direct substitute for the FDB8447L. This part maintains the 40V Vdss rating and TO-263 package footprint, ensuring PCB-level compatibility without layout modifications. The AOB4184 delivers 50A continuous drain current at case temperature, matching the FDB8447L specification. Although the continuous drain current at ambient temperature is rated at 12A (versus 15A for the FDB8447L), the case temperature rating of 50A is equivalent. The AOB4184 is in active product status with ROHS3 compliance and unlimited moisture sensitivity level (MSL 1), supporting long-term supply chain availability. Gate charge is lower at 35 nC, reducing driver power requirements.

STB170NF04 (STMicroelectronics) provides an alternative 40V direct replacement with enhanced current handling. This part delivers 80A continuous drain current at case temperature, exceeding the FDB8447L specification by 30A. The STB170NF04 is part of the STripFET™ II series and is in active product status. The lower RDS(on) of 5 mOhm (versus 8.5 mOhm for the FDB8447L) reduces conduction losses. Operating temperature extends to 175°C, providing additional thermal margin. Gate charge is significantly higher at 170 nC, requiring consideration in gate driver design. The TO-263 package maintains footprint compatibility.

For Higher Voltage Applications (55V Voltage Class, D2PAK Package):

BUK764R0-55B,118 (Nexperia USA Inc.) and PHB191NQ06LT,118 (Nexperia USA Inc.) are suitable for applications requiring voltage ratings above 40V. Both parts are rated for 55V Vdss and deliver 75A continuous drain current at case temperature. These parts are in active product status with ROHS3 compliance. The BUK764R0-55B,118 features 4 mOhm RDS(on) and is qualified to AEC-Q101 automotive standards. The PHB191NQ06LT,118 offers superior RDS(on) at 3.7 mOhm with lower gate threshold voltage of 2V. Both parts support operating temperatures to 175°C. D2PAK package footprint is compatible with TO-263 layouts. These substitutes are appropriate only when circuit design permits operation at 55V.

For Reduced Voltage Applications (30V Voltage Class, 8-PDFN Package):

TSM085N03PQ33 RGG (Taiwan Semiconductor Corporation) is suitable only for applications with 30V or lower voltage requirements. This part operates at 30V Vdss with 52A continuous drain current at case temperature. The 8-PDFN package differs from the TO-263 footprint, requiring PCB layout redesign. Gate charge is minimal at 14.3 nC, reducing driver power. This substitute is not recommended for direct replacement of the FDB8447L in existing designs due to voltage class mismatch and package incompatibility.

Compliance and Supply Considerations:

All substitute parts listed are ROHS3 compliant and REACH unaffected, meeting environmental regulatory requirements. All parts carry MSL 1 (unlimited moisture sensitivity), eliminating moisture-related handling constraints. Active product status for AOB4184, STB170NF04, BUK764R0-55B,118, PHB191NQ06LT,118, and TSM085N03PQ33 RGG ensures long-term availability and supply chain support, addressing the obsolescence of the FDB8447L.

Frequently Asked Questions (FAQ)

Q: Can AOB4184 be used as a direct replacement for FDB8447L without PCB modifications?

A: Yes. The AOB4184 maintains the 40V Vdss rating, 50A continuous drain current at case temperature, and TO-263 (D2PAK) package footprint. No PCB layout changes are required. The part is pin-compatible and electrically equivalent for applications designed for the FDB8447L voltage and current class.

Q: What is the primary difference between AOB4184 and STB170NF04?

A: Both parts are 40V rated and TO-263 packaged. The STB170NF04 delivers higher continuous drain current (80A versus 50A at case temperature) and lower RDS(on) (5 mOhm versus 10 mOhm), reducing conduction losses. The STB170NF04 has higher gate charge (170 nC versus 35 nC), requiring a more capable gate driver. Selection depends on current requirements and driver capability.

Q: Why are BUK764R0-55B,118 and PHB191NQ06LT,118 listed as substitutes if they have 55V ratings?

A: These parts are listed as substitutes for applications where higher voltage margin is beneficial. The 55V rating provides additional headroom above the 40V design specification. However, they are not direct replacements for circuits strictly designed for 40V operation. Use these parts only when circuit topology and design allow operation at 55V.

Q: Is TSM085N03PQ33 RGG suitable for replacing FDB8447L in existing designs?

A: No. The TSM085N03PQ33 RGG operates at 30V Vdss, which is below the FDB8447L 40V specification. Additionally, the 8-PDFN package differs from the TO-263 footprint, requiring PCB redesign. This part is suitable only for new designs with 30V or lower voltage requirements.

Q: What does "Product Status: Obsolete" mean for the FDB8447L?

A: Obsolete status indicates that onsemi has discontinued manufacturing and support for the FDB8447L. Existing inventory may be available, but long-term supply is not guaranteed. Substitute parts in active product status (AOB4184, STB170NF04, BUK764R0-55B,118, PHB191NQ06LT,118, TSM085N03PQ33 RGG) provide ongoing availability and manufacturer support.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed (AOB4184, STB170NF04, BUK764R0-55B,118, PHB191NQ06LT,118, TSM085N03PQ33 RGG) are ROHS3 compliant, meeting environmental and regulatory requirements equivalent to the FDB8447L.

Q: What is the significance of gate charge (Qg) differences between substitute parts?

A: Gate charge affects gate driver power consumption and switching speed. Lower gate charge (AOB4184 at 35 nC) reduces driver power requirements. Higher gate charge (STB170NF04 at 170 nC) requires a more capable driver but may improve switching characteristics. Selection depends on gate driver specifications and application switching frequency.

Q: Can I use a 55V-rated MOSFET in a 40V circuit?

A: Yes, provided the circuit design permits. A 55V-rated device (BUK764R0-55B,118 or PHB191NQ06LT,118) operates safely in a 40V circuit, offering additional voltage margin. However, the higher voltage rating does not provide performance benefits in a 40V application and may increase cost. Use 55V-rated parts only when design requirements justify the higher voltage specification.

Q: What package compatibility considerations apply to these substitutes?

A: AOB4184 and STB170NF04 use TO-263 (D2PAK) packages, directly compatible with FDB8447L PCB layouts. BUK764R0-55B,118 and PHB191NQ06LT,118 use D2PAK packages, also compatible with TO-263 footprints. TSM085N03PQ33 RGG uses 8-PDFN (3.1x3.1) package, requiring PCB redesign and is not footprint-compatible.

Q: How do RDS(on) values affect device selection?

A: RDS(on) determines conduction losses and heat dissipation. Lower RDS(on) reduces power loss and operating temperature. The FDB8447L has 8.5 mOhm RDS(on). STB170NF04 (5 mOhm) and PHB191NQ06LT,118 (3.7 mOhm) offer lower losses, beneficial for high-current applications. AOB4184 (10 mOhm) has slightly higher losses. Selection depends on thermal budget and efficiency requirements.

Q: What is the operating temperature range significance?

A: The FDB8447L operates from -55°C to 150°C. AOB4184, STB170NF04, BUK764R0-55B,118, and PHB191NQ06LT,118 extend to 175°C, providing additional thermal margin. TSM085N03PQ33 RGG matches the FDB8447L at -55°C to 150°C. Extended temperature range is beneficial for applications in harsh environments or with high ambient temperatures.

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