FDD6688 N-Channel 30V 84A MOSFET Equivalent & Substitute Parts

Part Overview

The FDD6688 is an N-Channel 30V 84A MOSFET manufactured by onsemi in the PowerTrench® series, housed in a TO-252AA (DPAK) surface mount package. This device is classified as obsolete, necessitating identification of equivalent and substitute components for ongoing design requirements and production continuity. The FDD6688 serves applications requiring high current switching capability at 30V drain-source voltage with low on-resistance characteristics.

Key Parameters

Parameter	FDD6688 Specification
Drain-Source Voltage (Vdss)	30 V
Continuous Drain Current (Id) @ 25°C	84 A (Ta)
On-Resistance (Rds On Max) @ Id, Vgs	5 mOhm @ 18A, 10V
Gate Threshold Voltage (Vgs(th) Max) @ Id	3 V @ 250 µA
Gate Charge (Qg Max) @ Vgs	56 nC @ 10 V
Input Capacitance (Ciss Max) @ Vds	3845 pF @ 15 V
Power Dissipation (Max)	83 W (Ta)
Operating Temperature Range	-55°C to 175°C (TJ)
Package Type	TO-252-3, DPAK (2 Leads + Tab), SC-63
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the FDD6688 is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

Drain-Source Voltage (Vdss): 30 V
Package Type: TO-252-3, DPAK (2 Leads + Tab), SC-63
Mounting Type: Surface Mount
Operating Temperature Range: -55°C to 175°C (TJ)
FET Type: N-Channel
Technology: MOSFET (Metal Oxide)

Performance Parameters for Functional Equivalence:

Continuous Drain Current (Id): Substitute must support minimum 84 A (Ta) or equivalent thermal rating
On-Resistance (Rds On): Substitute must not exceed 5 mOhm @ specified Id and Vgs conditions
Gate Charge (Qg): Substitute specifications must be compatible with existing gate drive circuitry
Input Capacitance (Ciss): Substitute must maintain similar capacitive loading characteristics

Substitute parts are grouped based on their ability to meet or exceed the FDD6688 electrical specifications while maintaining identical package and mounting compatibility. Parts with lower current ratings, higher on-resistance, or different thermal characteristics are included where they provide functional alternatives for reduced-stress applications.

Parameter Comparison

Parameter	FDD6688	NTD4965NT4G	NVD4C05NT4G	AOD514	IPD040N03LGATMA1	IRLR7833TRPBF	STD17NF03LT4	STD86N3LH5	STD96N3LLH6
Vdss (V)	30	30	30	30	30	30	30	30	30
Id @ 25°C (A) Ta/Tc	84 (Ta)	13 (Ta) / 68 (Tc)	22 (Ta) / 90 (Tc)	17 (Ta) / 46 (Tc)	90 (Tc)	140 (Tc)	17 (Tc)	80 (Tc)	80 (Tc)
Rds On Max (mOhm) @ Id, Vgs	5 @ 18A, 10V	4.7 @ 30A, 10V	4.1 @ 45A, 10V	6.5 @ 20A, 10V	4 @ 30A, 10V	4.5 @ 15A, 10V	50 @ 8.5A, 10V	5 @ 40A, 10V	4.2 @ 40A, 10V
Vgs(th) Max (V) @ Id	3 @ 250µA	2.5 @ 250µA	2.2 @ 250µA	2.6 @ 250µA	2.2 @ 250µA	2.3 @ 250µA	2.2 @ 250µA	2.5 @ 250µA	2.5 @ 250µA
Qg Max (nC) @ Vgs	56 @ 10V	17.2 @ 4.5V	14 @ 4.5V	22.5 @ 10V	38 @ 10V	50 @ 4.5V	6.5 @ 5V	14 @ 5V	20 @ 4.5V
Ciss Max (pF) @ Vds	3845 @ 15V	1710 @ 15V	1950 @ 25V	951 @ 15V	3900 @ 15V	4010 @ 15V	320 @ 25V	1850 @ 25V	2200 @ 25V
Power Dissipation Max (W) Ta/Tc	83 (Ta)	1.39 (Ta)	3.5 (Ta) / 57 (Tc)	2.5 (Ta) / 50 (Tc)	79 (Tc)	140 (Tc)	30 (Tc)	70 (Tc)	70 (Tc)
Operating Temp Range (°C)	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175	-55 to 175
Package	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK	TO-252-3 DPAK
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Not For New Designs	Active	Not For New Designs	Active	Active	Active

Engineering Selection Recommendations

Primary Substitutes (Active Product Status):

NVD4C05NT4G (onsemi) represents the most direct functional equivalent. This part maintains 30V Vdss, achieves 90A continuous drain current at Tc (exceeding the FDD6688 84A Ta rating), and provides superior on-resistance of 4.1 mOhm. The NVD4C05NT4G carries AEC-Q101 automotive qualification and active product status, ensuring long-term availability and supply chain stability. Input capacitance of 1950 pF is lower than the FDD6688, reducing gate drive requirements.

STD86N3LH5 (STMicroelectronics) and STD96N3LLH6 (STMicroelectronics) both deliver 80A continuous drain current at Tc with 70W power dissipation. STD86N3LH5 provides 5 mOhm on-resistance matching the FDD6688 specification, while STD96N3LLH6 offers improved 4.2 mOhm on-resistance. Both devices carry AEC-Q101 automotive qualification and active product status. These parts are suitable for applications where the 84A Ta rating of the FDD6688 can be mapped to the 80A Tc thermal rating of the substitute.

IPD040N03LGATMA1 (Infineon Technologies) provides 90A continuous drain current at Tc with 79W power dissipation and 4 mOhm on-resistance. This OptiMOS™ series device maintains active product status and full compliance with RoHS3 and REACH requirements.

Secondary Substitutes (Reduced Current Rating):

STD17NF03LT4 (STMicroelectronics) is suitable for applications where continuous drain current requirements are reduced to 17A. This part carries active product status but exhibits significantly higher on-resistance of 50 mOhm, limiting its use to lower-power switching applications.

Obsolete or Not For New Designs Status:

AOD514 (Alpha & Omega Semiconductor Inc.) and IRLR7833TRPBF (Infineon Technologies) carry "Not For New Designs" status. While AOD514 provides 46A Tc rating and IRLR7833TRPBF delivers 140A Tc rating, both are restricted from new design implementation. These parts are listed for reference in legacy system maintenance only.

NTD4965NT4G (onsemi) exhibits significantly reduced continuous drain current of 13A Ta / 68A Tc and power dissipation of 1.39W Ta, making it unsuitable as a direct substitute for the FDD6688 in high-current applications.

Frequently Asked Questions (FAQ)

Q: Can the NVD4C05NT4G directly replace the FDD6688 in existing designs?

A: The NVD4C05NT4G maintains identical 30V Vdss rating, TO-252-3 DPAK package, and operating temperature range. The part exceeds the FDD6688 current rating (90A Tc versus 84A Ta) and provides superior on-resistance (4.1 mOhm versus 5 mOhm). Pin-to-pin compatibility is confirmed. However, the lower input capacitance (1950 pF versus 3845 pF) may require gate drive circuit evaluation to ensure adequate switching speed.

Q: What is the difference between Ta and Tc current ratings?

A: Ta represents continuous drain current at ambient temperature (25°C), while Tc represents continuous drain current at case temperature (25°C). The FDD6688 specifies 84A Ta, indicating this current is sustainable with the device at 25°C ambient. Substitute parts using Tc ratings require thermal management to maintain case temperature at 25°C. For equivalent thermal performance, compare power dissipation specifications and thermal resistance characteristics.

Q: Are all substitute parts RoHS3 compliant?

A: All substitute parts listed in this reference carry ROHS3 Compliant status. The FDD6688 is also ROHS3 compliant. All parts maintain Moisture Sensitivity Level 1 (Unlimited), indicating no moisture sensitivity restrictions.

Q: Which substitute offers the best on-resistance performance?

A: The IPD040N03LGATMA1 provides the lowest on-resistance at 4 mOhm @ 30A, 10V, followed by NVD4C05NT4G at 4.1 mOhm @ 45A, 10V, and STD96N3LLH6 at 4.2 mOhm @ 40A, 10V. Lower on-resistance reduces power dissipation and heat generation in switching applications.

Q: Can I use STD17NF03LT4 as a substitute for the FDD6688?

A: STD17NF03LT4 is suitable only for applications where continuous drain current requirements are 17A or lower. The 50 mOhm on-resistance is significantly higher than the FDD6688 (5 mOhm), resulting in substantially increased power dissipation. This part is not recommended as a direct substitute for 84A applications.

Q: What is the significance of gate charge (Qg) differences between parts?

A: Gate charge determines the energy required to switch the MOSFET on and off. The FDD6688 requires 56 nC @ 10V, while substitutes range from 6.5 nC (STD17NF03LT4) to 50 nC (IRLR7833TRPBF). Lower gate charge reduces switching losses and allows faster switching speeds with lower gate drive current. Gate drive circuits must be evaluated to confirm compatibility with substitute gate charge specifications.

Q: Why is product status important for component selection?

A: Active product status ensures long-term availability, ongoing manufacturing support, and supply chain continuity. The FDD6688 is obsolete, necessitating substitution. NVD4C05NT4G, STD86N3LH5, STD96N3LLH6, IPD040N03LGATMA1, and STD17NF03LT4 all carry active product status, guaranteeing future availability. Parts marked "Not For New Designs" should be used only for legacy system maintenance.

Q: Are there automotive-qualified alternatives?

A: NVD4C05NT4G and STD86N3LH5 both carry AEC-Q101 automotive qualification, making them suitable for automotive applications requiring qualified components. These parts are recommended for designs with automotive qualification requirements.

Q: How do input capacitance differences affect circuit design?

A: Input capacitance (Ciss) affects gate drive circuit design and switching speed. The FDD6688 has 3845 pF @ 15V, while substitutes range from 320 pF (STD17NF03LT4) to 4010 pF (IRLR7833TRPBF). Higher capacitance requires greater gate drive current to achieve the same switching speed. Gate drive circuits must be verified to deliver sufficient current for the substitute part's capacitance.

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