FDS8670 N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The FDS8670 is an N-Channel 30V MOSFET manufactured by onsemi in the PowerTrench® series, rated for 21A continuous drain current at 25°C with 2.5W power dissipation. The device is packaged in 8-SOIC surface mount configuration and operates across the temperature range of -55°C to 150°C (TJ).

The FDS8670 carries an Obsolete product status. Equivalent and substitute parts are necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this MOSFET topology.

Key Parameters

Parameter	FDS8670 Specification
Manufacturer	onsemi
FET Type	N-Channel
Drain to Source Voltage (Vdss)	30 V
Current - Continuous Drain (Id) @ 25°C	21A (Ta)
Rds On (Max) @ Id, Vgs	3.7mOhm @ 21A, 10V
Gate Charge (Qg) (Max) @ Vgs	82 nC @ 10 V
Input Capacitance (Ciss) (Max) @ Vds	4040 pF @ 15 V
Power Dissipation (Max)	2.5W (Ta)
Operating Temperature Range	-55°C ~ 150°C (TJ)
Mounting Type	Surface Mount
Package / Case	8-SOIC (0.154", 3.90mm Width)
Vgs (Max)	±20V
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the FDS8670 is determined by strict alignment of the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Drain to Source Voltage (Vdss): 30V minimum
Continuous Drain Current (Id) @ 25°C: 21A minimum
On-State Resistance (Rds On): 3.7mOhm or lower @ 10V gate drive
Power Dissipation (Max): 2.5W or greater
Gate Charge (Qg): 82nC or lower @ 10V
Input Capacitance (Ciss): 4040pF or lower @ 15V
Operating Temperature Range: -55°C to 150°C minimum
Package: 8-SOIC surface mount configuration
Gate Voltage (Vgs): ±20V maximum rating

Secondary Compatibility Factors:

Technology: MOSFET (Metal Oxide)
Mounting Type: Surface Mount
Supplier Device Package: 8-SOIC or equivalent 8-pin surface mount

Substitute parts are grouped into two categories based on electrical performance alignment:

Category A - Direct Electrical Equivalents (21A Rating): Parts meeting or exceeding the 21A continuous drain current specification with matching or superior on-state resistance characteristics.

Category B - Reduced Current Alternatives (16-17A Rating): Parts with lower continuous drain current ratings (16-17A) but compatible voltage and package specifications. These parts are suitable for applications where the full 21A capability is not required.

Parameter Comparison

Parameter	FDS8670	IRF8734TRPBF	IRF7862TRPBF	BSO033N03MSGXUMA1	BSO040N03MSGXUMA1
Manufacturer	onsemi	Infineon	Infineon	Infineon	Infineon
Series	PowerTrench®	HEXFET®	HEXFET®	OptiMOS™	OptiMOS™
Vdss (V)	30	30	30	30	30
Id @ 25°C (A)	21	21	21	17	16
Rds On (Max) @ 10V (mOhm)	3.7 @ 21A	3.5 @ 21A	3.7 @ 20A	3.3 @ 22A	4.0 @ 20A
Gate Charge Qg @ 10V (nC)	82	30	45	124	73
Input Capacitance Ciss @ 15V (pF)	4040	3175	4090	9600	5700
Power Dissipation (Max) (W)	2.5	2.5	2.5	1.56	1.56
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150
Package	8-SOIC	8-SOIC	8-SOIC	PG-DSO-8	PG-DSO-8
Vgs (Max) (V)	±20	±20	±20	±20	±20
Product Status	Obsolete	Active	Active	Not For New Designs	Not For New Designs
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	3 (168 Hours)	3 (168 Hours)

Engineering Selection Recommendations

Primary Substitutes (Direct Electrical Equivalents):

The IRF8734TRPBF and IRF7862TRPBF are the preferred substitutes for the FDS8670. Both devices are manufactured by Infineon Technologies and maintain electrical equivalence across all critical parameters:

Both devices provide 21A continuous drain current at 25°C
On-state resistance specifications (3.5-3.7mOhm @ 10V) match or exceed the FDS8670 performance
Power dissipation rating of 2.5W accommodates identical thermal requirements
Operating temperature range (-55°C to 150°C) is fully compatible
8-SOIC package configuration ensures mechanical compatibility
Both devices carry Active product status, ensuring long-term supply availability
Both devices are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating

The IRF8734TRPBF offers superior gate charge characteristics (30nC @ 4.5V) and lower input capacitance (3175pF @ 15V), resulting in improved switching performance and reduced drive circuit requirements.

The IRF7862TRPBF provides balanced performance with gate charge of 45nC @ 4.5V and input capacitance of 4090pF @ 15V, maintaining close alignment with the original FDS8670 specifications.

Secondary Substitutes (Reduced Current Alternatives):

The BSO033N03MSGXUMA1 and BSO040N03MSGXUMA1 are Infineon OptiMOS™ devices suitable for applications where continuous drain current requirements do not exceed 17A and 16A respectively:

BSO033N03MSGXUMA1: 17A continuous drain current, 3.3mOhm Rds On @ 22A, 10V
BSO040N03MSGXUMA1: 16A continuous drain current, 4.0mOhm Rds On @ 20A, 10V

These devices are not recommended for direct replacement in applications requiring the full 21A capability. Both carry "Not For New Designs" product status and MSL 3 (168 Hours) moisture sensitivity rating, indicating restricted availability for new production designs.

Compliance and Certification:

All substitute parts maintain REACH Unaffected status and EAR99 export classification, consistent with the original FDS8670. All Infineon substitutes are ROHS3 compliant, supporting environmental and regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the IRF8734TRPBF directly replace the FDS8670 in existing designs?

A: Yes. The IRF8734TRPBF meets or exceeds all critical electrical parameters of the FDS8670, including 30V Vdss rating, 21A continuous drain current, 3.5mOhm on-state resistance, and 2.5W power dissipation. The 8-SOIC package configuration is mechanically identical. Pin-to-pin compatibility requires verification against the specific application schematic.

Q: What is the difference between the IRF8734TRPBF and IRF7862TRPBF?

A: Both devices provide identical voltage, current, and power dissipation ratings. The IRF8734TRPBF features lower gate charge (30nC @ 4.5V versus 45nC @ 4.5V) and lower input capacitance (3175pF versus 4090pF), resulting in faster switching transitions and reduced gate drive power requirements. The IRF7862TRPBF maintains closer alignment with the original FDS8670 gate charge specification (82nC @ 10V).

Q: Are the BSO033N03MSGXUMA1 and BSO040N03MSGXUMA1 suitable replacements?

A: These devices are suitable only for applications where the continuous drain current requirement does not exceed 17A (BSO033N03MSGXUMA1) or 16A (BSO040N03MSGXUMA1). Both devices carry "Not For New Designs" status, indicating restricted availability. The reduced power dissipation rating (1.56W versus 2.5W) requires thermal design verification for applications with high duty cycle operation.

Q: What is the significance of the MSL (Moisture Sensitivity Level) rating difference?

A: The FDS8670 and Infineon HEXFET® substitutes (IRF8734TRPBF, IRF7862TRPBF) carry MSL 1 (Unlimited), indicating no moisture-related storage restrictions. The Infineon OptiMOS™ devices (BSO033N03MSGXUMA1, BSO040N03MSGXUMA1) carry MSL 3 (168 Hours), requiring controlled storage conditions and bake-out procedures before reflow soldering. This affects supply chain handling and production scheduling.

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 FDS8670 specifies 82nC @ 10V. The IRF8734TRPBF (30nC @ 4.5V) requires significantly less gate charge, reducing gate drive circuit power dissipation and enabling faster switching. The IRF7862TRPBF (45nC @ 4.5V) provides intermediate performance. Lower gate charge is advantageous in high-frequency switching applications and reduces electromagnetic interference.

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

A: The IRF8734TRPBF is available in Cut Tape (CT) and Digi-Reel® packaging. The IRF7862TRPBF is available in Tape & Reel (TR) packaging. The BSO033N03MSGXUMA1 and BSO040N03MSGXUMA1 are available in Tape & Reel (TR) packaging. Packaging format selection depends on production volume and assembly equipment compatibility.

Q: What is the product status significance for long-term supply planning?

A: The FDS8670 carries Obsolete status, indicating discontinued production. The IRF8734TRPBF and IRF7862TRPBF carry Active status, ensuring continued manufacturing and long-term availability. The BSO033N03MSGXUMA1 and BSO040N03MSGXUMA1 carry "Not For New Designs" status, indicating restricted availability and potential discontinuation. For new production designs, the Active-status Infineon HEXFET® devices are recommended.

Q: Can input capacitance differences affect circuit design?

A: Input capacitance (Ciss) affects gate drive circuit impedance and switching speed. The FDS8670 specifies 4040pF @ 15V. The IRF8734TRPBF (3175pF) provides lower capacitance, enabling faster switching and reduced gate drive power. The IRF7862TRPBF (4090pF) maintains near-identical capacitance. The BSO033N03MSGXUMA1 (9600pF) exhibits significantly higher capacitance, requiring higher gate drive current and potentially affecting switching frequency performance.

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