FDS6299S N-Channel 30V 21A MOSFET Equivalent & Substitute Parts

Part Overview

The FDS6299S is an N-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 21A continuous drain current at 25°C. This device is packaged in an 8-SOIC surface mount configuration and belongs to the PowerTrench® series. The FDS6299S is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating available packaging and product status options.

Key Parameters

Parameter	FDS6299S Value	Unit
Drain-to-Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	21	A (Ta)
On-Resistance (Rds On Max) @ 21A, 10V	3.9	mOhm
Gate Threshold Voltage (Vgs(th)) @ 1mA	3	V
Gate Charge (Qg) @ 10V	81	nC
Input Capacitance (Ciss) @ 15V	3880	pF
Power Dissipation (Max)	3	W (Ta)
Operating Temperature Range	-55 to 150	°C (TJ)
Package Type	8-SOIC	Surface Mount
FET Type	N-Channel	MOSFET

Substitute Part Grouping Explanation

Substitution of the FDS6299S is determined by the following critical parameters:

Electrical Compatibility Requirements:

Drain-to-Source Voltage (Vdss) must equal or exceed 30V
Continuous Drain Current (Id) must equal or exceed 21A at 25°C
On-Resistance (Rds On) must not exceed the maximum specified value to maintain thermal performance
Gate Threshold Voltage (Vgs(th)) must be compatible with existing drive circuitry
Operating temperature range must encompass -55°C to 150°C

Mechanical Compatibility Requirements:

Package type must be 8-SOIC or equivalent surface mount configuration with identical pinout
Mounting type must be surface mount
Physical dimensions must be compatible with existing PCB layouts

Regulatory and Availability Considerations:

Product status (Active vs. Obsolete vs. Not For New Designs) affects long-term availability
RoHS and REACH compliance status must align with application requirements
Moisture Sensitivity Level (MSL) must be compatible with assembly processes

Substitute parts are grouped based on their ability to meet or exceed these parameters while maintaining form-factor compatibility and acceptable thermal characteristics.

Parameter Comparison

Parameter	FDS6299S	FDS8870	BSO040N03MSGXUMA1	IRF7832TRPBF	IRF7862TRPBF	IRF8734TRPBF	SI4842BDY-T1-E3
Manufacturer	onsemi	onsemi	Infineon	Infineon	Infineon	Infineon	Vishay Siliconix
Vdss (V)	30	30	30	30	30	30	30
Id @ 25°C (A)	21	18	16	20	21	21	28
Rds On Max @ 10V (mOhm)	3.9	4.2	4.0	4.0	3.7	3.5	4.2
Vgs(th) (V)	3.0	2.5	2.0	2.32	2.35	2.35	3.0
Qg @ 10V (nC)	81	112	73	51	45	30	100
Ciss @ 15V (pF)	3880	4615	5700	4310	4090	3175	3650
Power Dissipation (W)	3	2.5	1.56	2.5	2.5	2.5	3 / 6.25
Operating Temp (°C)	-55 to 150	-55 to 150	-55 to 150	-55 to 155	-55 to 150	-55 to 150	-55 to 150
Package	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Not For New Designs	Active	Active	Active	Active
RoHS Status	Not Specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
MSL Rating	1 (Unlimited)	1 (Unlimited)	3 (168 Hours)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

IRF8734TRPBF is the preferred substitute for the FDS6299S. This device matches the 21A continuous drain current specification exactly and provides superior on-resistance performance (3.5 mOhm vs. 3.9 mOhm). The IRF8734TRPBF is manufactured by Infineon, carries Active product status, and is ROHS3 compliant. The lower gate charge (30 nC vs. 81 nC) and reduced input capacitance (3175 pF vs. 3880 pF) provide improved switching performance. MSL rating of 1 (Unlimited) matches the original specification.

IRF7862TRPBF provides an alternative with identical 21A current rating and Active product status. On-resistance is 3.7 mOhm, slightly better than the original. Gate charge is significantly reduced to 45 nC, and input capacitance is 4090 pF. This device is ROHS3 compliant with MSL rating of 1 (Unlimited).

Secondary Substitutes (Acceptable with Design Verification):

SI4842BDY-T1-E3 from Vishay Siliconix exceeds the current specification at 28A continuous drain current, providing design margin. On-resistance is 4.2 mOhm. Power dissipation is rated at 3W (Ta) matching the original, with additional 6.25W (Tc) rating. This device is ROHS3 compliant with MSL rating of 1 (Unlimited). REACH status is listed as Affected, requiring compliance verification for specific applications.

IRF7832TRPBF provides 20A continuous drain current, slightly below the 21A specification. On-resistance is 4.0 mOhm. Gate charge is reduced to 51 nC. This device is ROHS3 compliant with Active product status and MSL rating of 1 (Unlimited).

FDS8870 is an onsemi alternative with 18A continuous drain current, below the original 21A specification. On-resistance is 4.2 mOhm. This device is ROHS3 compliant with Active product status and MSL rating of 1 (Unlimited). Use is limited to applications where 18A current capacity is sufficient.

Not Recommended:

BSO040N03MSGXUMA1 from Infineon provides only 16A continuous drain current, insufficient for applications requiring the full 21A specification. Product status is listed as Not For New Designs. MSL rating of 3 (168 Hours) requires controlled moisture handling during assembly. This device is not suitable for new designs or production requiring the original current rating.

Frequently Asked Questions (FAQ)

Q: Can the IRF8734TRPBF directly replace the FDS6299S without circuit modifications?

A: The IRF8734TRPBF is pin-compatible in the 8-SOIC package and meets all electrical specifications. However, the significantly lower gate charge (30 nC vs. 81 nC) and input capacitance (3175 pF vs. 3880 pF) may require gate drive circuit optimization to prevent overshoot or ringing. Verify gate drive voltage and current capability with the substitute device datasheet.

Q: What is the impact of using SI4842BDY-T1-E3 with its higher 28A current rating?

A: The higher current rating provides design margin and does not create compatibility issues. The on-resistance (4.2 mOhm) is slightly higher than the original (3.9 mOhm), resulting in marginally higher power dissipation under full load. The device is suitable for applications where the additional current capacity is beneficial or neutral. Verify thermal management remains adequate.

Q: Why is BSO040N03MSGXUMA1 not recommended as a substitute?

A: The BSO040N03MSGXUMA1 provides only 16A continuous drain current, which is insufficient for applications requiring the full 21A specification of the FDS6299S. Additionally, the product status is listed as Not For New Designs, limiting long-term availability and support. The MSL rating of 3 (168 Hours) requires controlled moisture handling during assembly, adding process complexity.

Q: Are all substitute parts ROHS3 compliant?

A: All substitute parts listed are ROHS3 compliant except the original FDS6299S, which does not specify RoHS status. The FDS8870, IRF7832TRPBF, IRF7862TRPBF, IRF8734TRPBF, and SI4842BDY-T1-E3 are all ROHS3 compliant. Verify REACH compliance status for your specific application, particularly for SI4842BDY-T1-E3, which is listed as REACH Affected.

Q: What is the significance of MSL rating differences?

A: Most substitute parts carry MSL rating of 1 (Unlimited), matching the original FDS6299S. The BSO040N03MSGXUMA1 carries MSL rating of 3 (168 Hours), requiring that the device be stored in a controlled moisture environment and reflowed within 168 hours of moisture exposure. This adds assembly process constraints and is not present in other substitutes.

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 FDS6299S requires 81 nC at 10V. Substitutes range from 30 nC (IRF8734TRPBF) to 112 nC (FDS8870). Lower gate charge reduces switching losses and allows faster switching speeds, but may require gate drive circuit adjustment to prevent instability. Higher gate charge increases switching losses but may provide better noise immunity in noisy environments.

Q: Can FDS8870 be used in applications requiring the full 21A specification?

A: The FDS8870 provides only 18A continuous drain current, which is 3A below the FDS6299S specification. Use is limited to applications where the actual operating current does not exceed 18A. For applications requiring the full 21A capability, use IRF8734TRPBF, IRF7862TRPBF, or SI4842BDY-T1-E3.

Q: What packaging considerations apply to these substitutes?

A: All substitute parts are packaged in 8-SOIC surface mount configuration with identical 0.154" (3.90mm) width, ensuring mechanical compatibility with existing PCB layouts. Pin assignments are standard for N-Channel MOSFETs in this package class. Verify pinout compatibility with your specific application before assembly.

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