FDS6694 Equivalent & Substitute Parts

Part Overview

The FDS6694 is an N-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 12A continuous drain current at 25°C. This device is housed in an 8-SOIC surface mount package and is part of the PowerTrench® series. The FDS6694 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating the 8-SOIC package footprint.

Key Parameters

Parameter	FDS6694 Specification
Drain-to-Source Voltage (Vdss)	30 V
Continuous Drain Current (Id) @ 25°C	12 A
On-Resistance (Rds On Max) @ Id, Vgs	11 mOhm @ 12A, 10V
Gate Threshold Voltage (Vgs(th) Max) @ Id	3 V @ 250 µA
Gate Charge (Qg Max) @ Vgs	19 nC @ 5 V
Maximum Gate Voltage (Vgs Max)	±20 V
Input Capacitance (Ciss Max) @ Vds	1293 pF @ 15 V
Power Dissipation (Max)	2.5 W
Operating Temperature Range (TJ)	-55°C to 175°C
Package Type	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the FDS6694 is determined by strict equivalence across the following critical parameters:

Voltage Rating: All substitute parts must maintain the 30V Vdss specification to ensure safe operation within the same circuit voltage domain.

Current Capability: Substitute parts must support the 12A continuous drain current requirement at 25°C. Parts with higher current ratings (13.6A) provide margin and are acceptable; parts with lower ratings (9.5A) do not meet the minimum requirement.

Package Compatibility: All substitute parts must use the 8-SOIC surface mount package with 0.154" (3.90mm) width to ensure PCB footprint compatibility without redesign.

Gate Drive Voltage: Substitute parts must operate with the same gate drive voltage range (4.5V to 10V for Rds On specification) to maintain compatibility with existing gate driver circuits.

Thermal Operating Range: The FDS6694 operates from -55°C to 175°C. Substitute parts with lower maximum junction temperatures (150°C or 155°C) represent a thermal constraint but remain functionally acceptable if circuit design does not require the full -55°C to 175°C range.

On-Resistance: Substitute parts with lower Rds On values (7 mOhm to 9.1 mOhm) provide improved efficiency and reduced power dissipation compared to the 11 mOhm specification of the FDS6694.

Parameter Comparison

Parameter	FDS6694 (onsemi)	IRF7821TRPBF (Infineon)	SI4874BDY-T1-E3 (Vishay)	SI4420BDY-T1-E3 (Vishay)
Drain-to-Source Voltage (Vdss)	30 V	30 V	30 V	30 V
Continuous Drain Current (Id) @ 25°C	12 A	13.6 A	12 A	9.5 A
On-Resistance (Rds On Max) @ Id, Vgs	11 mOhm @ 12A, 10V	9.1 mOhm @ 13A, 10V	7 mOhm @ 16A, 10V	8.5 mOhm @ 13.5A, 10V
Gate Threshold Voltage (Vgs(th) Max) @ Id	3 V @ 250 µA	1 V @ 250 µA	3 V @ 250 µA	3 V @ 250 µA
Gate Charge (Qg Max) @ Vgs	19 nC @ 5 V	14 nC @ 4.5 V	25 nC @ 4.5 V	50 nC @ 10 V
Maximum Gate Voltage (Vgs Max)	±20 V	±20 V	±20 V	±20 V
Input Capacitance (Ciss Max) @ Vds	1293 pF @ 15 V	1010 pF @ 15 V	3230 pF @ 15 V	Not specified
Power Dissipation (Max)	2.5 W	2.5 W	1.6 W	1.4 W
Operating Temperature Range (TJ)	-55°C to 175°C	-55°C to 155°C	-55°C to 150°C	-55°C to 150°C
Package Type	8-SOIC	8-SO	8-SOIC	8-SOIC
Product Status	Obsolete	Active	Active	Active
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

IRF7821TRPBF (Infineon Technologies): This part is classified as active and ROHS3 compliant. It provides 13.6A continuous drain current, exceeding the 12A requirement, with improved on-resistance of 9.1 mOhm. The maximum junction temperature of 155°C is 20°C lower than the FDS6694. This part is suitable for applications where the reduced thermal operating range does not conflict with system requirements. The 8-SO package is mechanically compatible with 8-SOIC footprints.

SI4874BDY-T1-E3 (Vishay Siliconix): This part is classified as active and ROHS3 compliant. It matches the 12A continuous drain current specification and provides superior on-resistance of 7 mOhm, resulting in lower power dissipation (1.6W versus 2.5W). The maximum junction temperature of 150°C is 25°C lower than the FDS6694. This part is suitable for applications prioritizing efficiency and thermal performance within the reduced temperature range. The 8-SOIC package provides direct footprint compatibility.

SI4420BDY-T1-E3 (Vishay Siliconix): This part is classified as active and ROHS3 compliant. However, the continuous drain current rating of 9.5A falls below the 12A requirement of the FDS6694. This part does not meet the minimum current specification and is not recommended as a direct substitute for applications requiring the full 12A capability.

Frequently Asked Questions (FAQ)

Q: Can the IRF7821TRPBF replace the FDS6694 in all applications?

A: The IRF7821TRPBF meets the voltage and current requirements and provides improved on-resistance. However, the maximum junction temperature is 155°C compared to 175°C for the FDS6694. Substitution is valid only if the circuit design does not require operation above 155°C junction temperature.

Q: Why is the SI4420BDY-T1-E3 listed if it has only 9.5A current rating?

A: The SI4420BDY-T1-E3 is included in the reference for informational purposes. It does not meet the 12A continuous drain current specification and is not suitable as a direct substitute for the FDS6694 in applications requiring the full rated current.

Q: Are the 8-SO and 8-SOIC packages interchangeable?

A: The 8-SO and 8-SOIC packages share the same 0.154" (3.90mm) width and pin pitch, making them mechanically compatible on standard PCB footprints. Both packages are surface mount configurations suitable for automated assembly.

Q: What is the impact of lower on-resistance in substitute parts?

A: Lower on-resistance (Rds On) reduces power dissipation during conduction, improving efficiency and reducing thermal load. The SI4874BDY-T1-E3 with 7 mOhm on-resistance dissipates less heat than the FDS6694 with 11 mOhm on-resistance at the same current level.

Q: Do all substitute parts have the same gate charge characteristics?

A: No. Gate charge varies across the substitute parts. The IRF7821TRPBF has 14 nC, the SI4874BDY-T1-E3 has 25 nC, and the SI4420BDY-T1-E3 has 50 nC. Gate driver circuits must be verified for compatibility with the specific gate charge of the selected substitute part.

Q: Are all substitute parts RoHS compliant?

A: Yes. The IRF7821TRPBF, SI4874BDY-T1-E3, and SI4420BDY-T1-E3 are all ROHS3 compliant, meeting current environmental and regulatory requirements.

Q: What is the significance of the obsolete status of the FDS6694?

A: The obsolete status indicates that onsemi has discontinued production of the FDS6694. Active substitute parts from Infineon and Vishay ensure continued availability and supply chain continuity for new designs and production support.

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