FDS6699S N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The FDS6699S is an N-Channel 30V 21A surface mount MOSFET manufactured by onsemi, utilizing PowerTrench® and SyncFET™ technology in an 8-SOIC package. This device is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design support and procurement. The part delivers 2.5W maximum power dissipation and operates across a temperature range of -55°C to 150°C (TJ). Substitute parts must maintain electrical compatibility across drain-source voltage, continuous drain current, on-resistance characteristics, and physical packaging to ensure functional equivalence in circuit applications.

Key Parameters

Parameter	FDS6699S	Unit
Drain to Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	21	A
Rds On (Max) @ 21A, 10V	3.6	mOhm
Gate Charge (Qg) @ 10V	91	nC
Input Capacitance (Ciss) @ 15V	3610	pF
Power Dissipation (Max)	2.5	W
Operating Temperature Range	-55 to 150	°C (TJ)
Package Type	8-SOIC	Surface Mount
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution eligibility for the FDS6699S is determined by the following critical parameters: Drain to Source Voltage (Vdss) of 30V, continuous drain current capability, on-resistance (Rds On) characteristics, surface mount 8-SOIC package compatibility, and operating temperature range. Parts are classified into two categories based on electrical performance alignment:

Direct Equivalent Category: Parts maintaining 21A continuous drain current at 30V with comparable on-resistance and 8-SOIC packaging.

Similar Performance Category: Parts with 30V Vdss rating but differing drain current ratings or on-resistance specifications, suitable for applications where current or power dissipation requirements permit deviation from the original specification.

All substitute parts must comply with RoHS3 and maintain surface mount 8-SOIC package geometry (0.154", 3.90mm width) for mechanical interchangeability.

Parameter Comparison

Parameter	FDS6699S (onsemi)	IRF8734TRPBF (Infineon)	SI4368DY-T1-E3 (Vishay)	TSM042N03CS RLG (Taiwan Semi)
Manufacturer	onsemi	Infineon Technologies	Vishay Siliconix	Taiwan Semiconductor
Vdss (V)	30	30	30	30
Id @ 25°C (A)	21	21	17	30
Rds On (Max) @ 10V (mOhm)	3.6 @ 21A	3.5 @ 21A	3.2 @ 25A	4.2 @ 12A
Gate Charge @ 4.5V or 10V (nC)	91 @ 10V	30 @ 4.5V	80 @ 4.5V	24 @ 4.5V
Input Capacitance @ 15V (pF)	3610	3175	8340	2200
Power Dissipation (Max) (W)	2.5	2.5	1.6	7
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 150	to 175
Package	8-SOIC	8-SOIC	8-SOIC	8-SOP
Product Status	Obsolete	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

IRF8734TRPBF (Infineon Technologies) is the primary direct equivalent for FDS6699S replacement. This part maintains identical 30V Vdss and 21A continuous drain current specifications with marginally lower on-resistance (3.5mOhm versus 3.6mOhm at 10V). The IRF8734TRPBF is classified as active product status, ensuring long-term availability and supply chain continuity. Both devices share 8-SOIC packaging, identical operating temperature range (-55°C to 150°C), and ROHS3 compliance. Gate charge is significantly lower (30nC versus 91nC), resulting in faster switching characteristics and reduced drive circuit power consumption.

SI4368DY-T1-E3 (Vishay Siliconix) serves as a similar performance substitute where continuous drain current requirements can be reduced to 17A. This part maintains 30V Vdss and 8-SOIC packaging with active product status. On-resistance is superior (3.2mOhm at 25A, 10V), and power dissipation is lower (1.6W). Gate charge and input capacitance differ significantly, requiring drive circuit evaluation. This substitute is suitable for applications where the 21A current rating exceeds actual circuit requirements.

TSM042N03CS RLG (Taiwan Semiconductor Corporation) provides higher current capability (30A continuous) at 30V with superior power dissipation (7W). This part is classified as active with extended maximum operating temperature (175°C). On-resistance specification differs (4.2mOhm at 12A, 10V), and gate charge is substantially lower (24nC). Package designation is 8-SOP rather than 8-SOIC, requiring mechanical compatibility verification. This substitute accommodates applications requiring higher current handling or thermal performance beyond the original FDS6699S specification.

All substitute parts maintain ROHS3 compliance and RoHS/REACH regulatory alignment with the original component.

Frequently Asked Questions (FAQ)

Q: Can IRF8734TRPBF directly replace FDS6699S without circuit modification?

A: IRF8734TRPBF is a direct electrical equivalent with matching 30V Vdss, 21A continuous drain current, and 8-SOIC package. The lower gate charge (30nC versus 91nC) may reduce drive circuit power consumption but does not prevent direct substitution. Verify gate drive voltage compatibility at 4.5V and 10V operating points.

Q: What is the primary difference between SI4368DY-T1-E3 and FDS6699S?

A: SI4368DY-T1-E3 has reduced continuous drain current (17A versus 21A) and lower power dissipation (1.6W versus 2.5W). Both maintain 30V Vdss and 8-SOIC packaging. This substitute is appropriate only when circuit current requirements do not exceed 17A continuous operation.

Q: Is TSM042N03CS RLG mechanically compatible with FDS6699S?

A: Both parts use 8-SOIC package designation with 0.154" (3.90mm) width. However, TSM042N03CS RLG is specified as 8-SOP package type. Physical footprint verification is required before PCB layout confirmation, as SOP and SOIC package variants may have dimensional differences in lead pitch or body height.

Q: Why does IRF8734TRPBF have lower gate charge than FDS6699S?

A: Gate charge is a manufacturing characteristic determined by die design and process technology. IRF8734TRPBF's lower gate charge (30nC at 4.5V versus 91nC at 10V) reflects Infineon's HEXFET® technology optimization. Lower gate charge reduces switching losses and drive circuit power requirements but does not affect on-resistance or current-carrying capability.

Q: Can TSM042N03CS RLG be used in applications requiring exactly 21A continuous current?

A: TSM042N03CS RLG is rated for 30A continuous drain current, exceeding the 21A requirement. This part is suitable for such applications. However, verify that the higher power dissipation capability (7W versus 2.5W) does not introduce thermal management changes or that the different on-resistance specification (4.2mOhm at 12A, 10V) aligns with circuit performance expectations.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. IRF8734TRPBF, SI4368DY-T1-E3, and TSM042N03CS RLG are all ROHS3 compliant, matching the regulatory status of FDS6699S. All parts are also REACH unaffected or REACH compliant.

Q: What is the impact of different input capacitance values on circuit performance?

A: Input capacitance (Ciss) affects gate drive circuit design and switching speed. FDS6699S has 3610pF at 15V, while IRF8734TRPBF has 3175pF, SI4368DY-T1-E3 has 8340pF, and TSM042N03CS RLG has 2200pF. Higher capacitance requires stronger gate drive current; lower capacitance permits faster switching. Evaluate gate driver output impedance and switching frequency requirements when selecting substitutes with significantly different Ciss values.

Q: Is the FDS6699S obsolete status a concern for new designs?

A: Yes. FDS6699S is classified as obsolete, indicating onsemi has discontinued production. IRF8734TRPBF, SI4368DY-T1-E3, and TSM042N03CS RLG are all active products with confirmed ongoing availability. New designs should incorporate active substitute parts to ensure long-term supply chain viability.

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