FDC3512 Equivalent & Substitute Parts

Part Overview

The FDC3512 is an N-Channel 80V 3A MOSFET manufactured by onsemi in the PowerTrench® series. This device is packaged in SuperSOT™-6 (SOT-23-6 Thin) surface mount configuration and is currently in Active product status. The FDC3512 serves applications requiring moderate current switching at 80V drain-source voltage ratings with low on-resistance characteristics.

Substitute parts are identified based on matching or exceeding the electrical performance parameters while maintaining compatibility with the primary application requirements. Alternatives are necessary when the FDC3512 reaches end-of-life status, when inventory constraints occur, or when design requirements allow for enhanced performance specifications.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	80	V
Continuous Drain Current (Id) @ 25°C	3	A
Rds On (Max) @ 3A, 10V	77	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V
Gate Charge (Qg) @ 10V	18	nC
Input Capacitance (Ciss) @ 40V	634	pF
Power Dissipation (Max)	1.6	W
Operating Temperature Range	-55 to 150	°C
Package Type	SOT-23-6 Thin (TSOT-23-6)	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitute parts for the FDC3512 are qualified based on the following electrical and mechanical criteria:

Primary Substitution Criteria:

Drain to Source Voltage (Vdss): Equal to or greater than 80V
FET Type: N-Channel MOSFET technology
Gate Threshold Voltage (Vgs(th)): Compatible with 4V specification
Maximum Gate Voltage (Vgs): ±20V tolerance
RoHS3 Compliance and MSL Level 1 rating
Surface Mount configuration

Secondary Performance Considerations:

Continuous Drain Current (Id): Equal to or exceeding 3A
On-Resistance (Rds On): Equal to or lower than 77mOhm at rated conditions
Gate Charge (Qg): Lower or equivalent values preferred for switching efficiency
Operating Temperature Range: Minimum -55°C to 150°C

The FDC3512 has two identified substitutes: FDS3512 (onsemi, Obsolete status) and SI3476DV-T1-GE3 (Vishay Siliconix, Active status). Both meet the core electrical requirements while offering enhanced current ratings and thermal performance.

Parameter Comparison

Parameter	FDC3512	FDS3512	SI3476DV-T1-GE3	Unit
Manufacturer	onsemi	onsemi	Vishay Siliconix	—
Product Status	Active	Obsolete	Active	—
Drain to Source Voltage (Vdss)	80	80	80	V
Continuous Drain Current (Id) @ 25°C	3	4	4.6	A
Rds On (Max) @ 10V	77 @ 3A	70 @ 4A	93 @ 3.5A	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	4	3	V
Gate Charge (Qg) @ 10V	18	18	7.5	nC
Input Capacitance (Ciss) @ 40V	634	634	195	pF
Power Dissipation (Max)	1.6	2.5	2 (Ta) / 3.6 (Tc)	W
Operating Temperature Range	-55 to 150	-55 to 175	-55 to 150	°C
Package Type	SOT-23-6 Thin	8-SOIC	SOT-23-6 Thin	—
RoHS3 Compliance	Yes	Yes	Yes	—
MSL Rating	1	1	1	—

Engineering Selection Recommendations

FDC3512 (Primary Part - Active Status)

The FDC3512 remains the preferred selection for new designs and ongoing production. Active product status ensures long-term availability and supply chain stability. This part is recommended for applications where the 3A continuous drain current and 1.6W power dissipation specifications are sufficient.

SI3476DV-T1-GE3 (Recommended Substitute - Active Status)

The SI3476DV-T1-GE3 from Vishay Siliconix is the preferred substitute for the FDC3512. Both devices maintain identical package geometry (SOT-23-6 Thin), enabling direct PCB layout compatibility. The SI3476DV-T1-GE3 provides superior electrical performance with 4.6A continuous drain current, lower gate charge (7.5nC versus 18nC), and reduced input capacitance (195pF versus 634pF). These characteristics result in improved switching efficiency and reduced gate drive requirements. Active product status ensures continued availability. The device is suitable for applications requiring enhanced thermal performance or higher current capacity within the same voltage class.

FDS3512 (Alternative Substitute - Obsolete Status)

The FDS3512 is identified as a manufacturer-recommended substitute but carries Obsolete product status. This part offers 4A continuous drain current and improved on-resistance (70mOhm) compared to the FDC3512. However, the package configuration differs (8-SOIC versus SOT-23-6 Thin), requiring PCB redesign and layout modifications. The extended operating temperature range (-55°C to 175°C) provides thermal margin for high-temperature applications. Obsolete status restricts this option to legacy system maintenance or when existing inventory is available. New designs should avoid this part due to supply discontinuation risk.

Compliance and Certification

All three parts maintain ROHS3 compliance, REACH Unaffected status, and MSL Level 1 (Unlimited) moisture sensitivity rating. EAR99 export classification and identical HTSUS codes confirm regulatory equivalence across all substitutes.

Frequently Asked Questions (FAQ)

Q: Can the SI3476DV-T1-GE3 directly replace the FDC3512 without PCB modifications?

A: Yes. Both devices use identical SOT-23-6 Thin package geometry and pinout configuration, enabling direct PCB substitution without layout changes. Electrical parameter compatibility is confirmed across gate threshold voltage, maximum gate voltage, and drain-source voltage specifications.

Q: What are the key performance differences between FDC3512 and SI3476DV-T1-GE3?

A: The SI3476DV-T1-GE3 provides higher continuous drain current (4.6A versus 3A), significantly lower gate charge (7.5nC versus 18nC), and reduced input capacitance (195pF versus 634pF). These improvements reduce switching losses and gate drive power requirements. On-resistance comparison depends on current level: FDC3512 achieves 77mOhm at 3A while SI3476DV-T1-GE3 measures 93mOhm at 3.5A, indicating comparable performance at respective rated currents.

Q: Why is FDS3512 listed as Obsolete?

A: FDS3512 carries Obsolete product status, indicating onsemi has discontinued active production and support. This classification restricts its use to legacy system maintenance where existing inventory is available. New designs should prioritize Active status parts to ensure long-term supply chain reliability.

Q: Can FDS3512 replace FDC3512 on existing PCBs?

A: No. FDS3512 uses 8-SOIC package configuration while FDC3512 uses SOT-23-6 Thin. Package incompatibility requires PCB redesign, including footprint modification and potential routing changes. This substitution is not recommended for direct board-level replacement.

Q: What is the significance of lower gate charge in the SI3476DV-T1-GE3?

A: Gate charge (Qg) of 7.5nC versus 18nC in the FDC3512 reduces the charge required to switch the transistor on and off. Lower gate charge decreases gate drive power consumption, enables faster switching transitions, and reduces electromagnetic interference in high-frequency applications. This parameter is critical for efficiency-sensitive designs.

Q: Are all three parts suitable for -55°C to 150°C operating range applications?

A: Yes. FDC3512 and SI3476DV-T1-GE3 both specify -55°C to 150°C operating temperature range. FDS3512 extends to 175°C maximum junction temperature, providing additional thermal margin for high-temperature environments. All three parts meet the baseline temperature requirement.

Q: What compliance certifications apply to all substitute parts?

A: All three parts maintain ROHS3 compliance, REACH Unaffected status, MSL Level 1 (Unlimited) moisture sensitivity rating, and EAR99 export classification. These certifications confirm regulatory equivalence and suitability for commercial and industrial applications without additional compliance verification.

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