FS8K Equivalent & Substitute Parts

Part Overview

The FS8K is a general-purpose rectifier diode manufactured by onsemi, rated for 800V DC reverse voltage and 8A average rectified current in a surface mount TO-277-3 package. This component is classified as not for new designs, indicating it has been superseded in onsemi's product portfolio. Equivalent and substitute parts are necessary for applications requiring continued sourcing, design flexibility, or alternative supplier options while maintaining electrical and mechanical compatibility.

Key Parameters

Parameter	Value	Unit
Voltage - DC Reverse (Vr) (Max)	800	V
Current - Average Rectified (Io)	8	A
Voltage - Forward (Vf) (Max) @ If	1.1 @ 8 A	V
Speed	Standard Recovery >500ns, > 200mA (Io)	—
Reverse Recovery Time (trr)	3.37	µs
Current - Reverse Leakage @ Vr	5	µA @ 800 V
Operating Temperature - Junction	-55 to 150	°C
Mounting Type	Surface Mount	—
Package / Case	TO-277, 3-PowerDFN	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—
Grade	Automotive	—
Qualification	AEC-Q101	—

Substitute Part Grouping Explanation

Substitution of rectifier diodes is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Voltage - DC Reverse (Vr) (Max): Must equal or exceed 800V
Current - Average Rectified (Io): Must equal or exceed 8A
Voltage - Forward (Vf) (Max) @ If: Must not exceed 1.1V @ 8A
Current - Reverse Leakage @ Vr: Must not exceed 5µA @ 800V
Operating Temperature - Junction: Must span -55°C to 150°C minimum

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount required
Package / Case: TO-277 family variants (TO-277, TO-277-3, TO-277A, TO-277B) with 3-PowerDFN footprint compatibility
Packaging: Tape & Reel (TR) format

Compliance Criteria:

RoHS3 Compliance required
REACH Unaffected status required

Substitute parts are classified into two categories: parametric equivalents (matching all electrical specifications) and functional substitutes (meeting minimum electrical requirements with package variations).

Parameter Comparison

Parameter	FS8K (onsemi)	GV808B_R2_00001 (Panjit)	GV808_R1_00001 (Panjit)	S8PK-M3/H (Vishay)
Voltage - DC Reverse (Vr) (Max)	800 V	800 V	800 V	800 V
Current - Average Rectified (Io)	8 A	8 A	8 A	2 A
Voltage - Forward (Vf) (Max) @ If	1.1 V @ 8 A	1.1 V @ 8 A	1.1 V @ 8 A	1.1 V @ 8 A
Speed	Standard Recovery >500ns, > 200mA (Io)	Standard Recovery >500ns, > 200mA (Io)	Standard Recovery >500ns, > 200mA (Io)	Standard Recovery >500ns, > 200mA (Io)
Reverse Recovery Time (trr)	3.37 µs	Not specified	Not specified	5 µs
Current - Reverse Leakage @ Vr	5 µA @ 800 V	5 µA @ 800 V	5 µA @ 800 V	5 µA @ 800 V
Capacitance @ Vr, F	118 pF @ 0V, 1MHz	55 pF @ 4V, 1MHz	55 pF @ 4V, 1MHz	60 pF @ 4V, 1MHz
Operating Temperature - Junction	-55°C to 150°C	-55°C to 150°C	-55°C to 150°C	-55°C to 150°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-277, 3-PowerDFN	TO-277, 3-PowerDFN	TO-277, 3-PowerDFN	TO-277, 3-PowerDFN
Supplier Device Package	TO-277-3	TO-277B	TO-277	TO-277A (SMPC)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected
Product Status	Not For New Designs	Active	Active	Active

Engineering Selection Recommendations

Parametric Equivalents (Full Substitution):

GV808B_R2_00001 and GV808_R1_00001 from Panjit International Inc. are parametric equivalents to the FS8K. Both parts match the 8A current rating, 800V reverse voltage, and 1.1V forward voltage specifications. Both manufacturers' parts carry active product status, ROHS3 compliance, and REACH unaffected designation. The Panjit parts are available in TO-277B and TO-277 package variants respectively, which are mechanically compatible within the TO-277 family footprint. These parts are suitable for direct replacement in applications where the FS8K is currently specified.

Functional Substitute (Current Rating Limitation):

S8PK-M3/H from Vishay General Semiconductor - Diodes Division meets the voltage and forward voltage specifications but is rated for 2A average rectified current, compared to the FS8K's 8A rating. This part is suitable only for applications where the actual circuit current requirement does not exceed 2A. The Vishay part carries active product status, ROHS3 compliance, and REACH unaffected designation. The TO-277A (SMPC) package variant is mechanically compatible with the TO-277 family footprint.

Compliance Considerations:

All substitute parts maintain ROHS3 compliance and REACH unaffected status, consistent with the FS8K. The FS8K carries automotive grade qualification (AEC-Q101); substitute parts should be evaluated for automotive qualification requirements if the application demands such certification.

Frequently Asked Questions (FAQ)

Q: Can GV808B_R2_00001 or GV808_R1_00001 be used as direct replacements for FS8K?

A: Yes. Both Panjit parts are parametric equivalents, matching the 8A current rating, 800V reverse voltage, 1.1V forward voltage, and operating temperature range. Both are surface mount components in TO-277 family packages with ROHS3 compliance and active product status.

Q: What is the difference between GV808B_R2_00001 and GV808_R1_00001?

A: Both parts are electrically identical with matching current, voltage, and temperature specifications. The difference is in the supplier device package designation: GV808B_R2_00001 uses TO-277B, while GV808_R1_00001 uses TO-277. Both are mechanically compatible within the TO-277 family footprint.

Q: Can S8PK-M3/H replace FS8K in all applications?

A: No. S8PK-M3/H is rated for 2A average rectified current, while FS8K is rated for 8A. S8PK-M3/H is suitable only for applications where circuit current does not exceed 2A. Voltage and temperature specifications are compatible.

Q: Are there package compatibility concerns when substituting these parts?

A: All substitute parts use TO-277 family packages (TO-277, TO-277-3, TO-277A, TO-277B) with 3-PowerDFN footprint designation. These variants are mechanically compatible for surface mount assembly. Verify PCB footprint design accommodates the specific package variant selected.

Q: Why is FS8K marked as "Not For New Designs"?

A: This designation indicates onsemi has superseded the FS8K in their product portfolio. Parametric equivalents from Panjit (GV808B_R2_00001, GV808_R1_00001) carry active product status and are recommended for new design applications requiring 8A, 800V rectifier diodes.

Q: Do all substitute parts meet automotive qualification requirements?

A: FS8K carries AEC-Q101 automotive qualification. Substitute parts should be individually verified for automotive qualification if the application requires such certification. Panjit and Vishay parts listed carry ROHS3 compliance and REACH unaffected status consistent with FS8K.

Q: What is the significance of the reverse recovery time (trr) difference?

A: FS8K specifies 3.37µs reverse recovery time. S8PK-M3/H specifies 5µs. Both fall within standard recovery classification (>500ns, >200mA). Panjit parts do not specify trr but meet standard recovery speed classification. For applications sensitive to switching transients, verify trr specifications against circuit requirements.

Q: Are moisture sensitivity levels equivalent across all parts?

A: FS8K and both Panjit parts specify MSL 1 (Unlimited). S8PK-M3/H does not specify MSL in the provided data. Verify moisture sensitivity requirements for storage and handling procedures if MSL classification is critical to manufacturing processes.

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