FDR4420A Equivalent & Substitute Parts

Part Overview

The FDR4420A is an N-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 11A continuous drain current at 25°C. The device is housed in a SuperSOT™-8 surface mount package and is designed for general-purpose switching and amplification applications requiring moderate voltage and current handling.

The FDR4420A is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications currently utilizing this component.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Technology	MOSFET (Metal Oxide)	—
Drain to Source Voltage (Vdss)	30	V
Current - Continuous Drain (Id) @ 25°C	11	A
Rds On (Max) @ Id, Vgs	9 mOhm @ 11A, 10V	—
Vgs(th) (Max) @ Id	3	V @ 250µA
Gate Charge (Qg) (Max) @ Vgs	33	nC @ 5V
Power Dissipation (Max)	1.8	W
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	8-LSOP (0.130", 3.30mm Width)	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the FDR4420A is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

FET Type: Must be N-Channel MOSFET
Drain to Source Voltage (Vdss): Substitute must equal or exceed 30V
Continuous Drain Current (Id): Substitute must equal or exceed 11A at 25°C
On-State Resistance (Rds On): Substitute must not exceed 9 mOhm at rated current and gate voltage
Gate Threshold Voltage (Vgs(th)): Must be compatible with existing gate drive circuitry
Power Dissipation: Substitute must handle thermal requirements of the application
Operating Temperature Range: Substitute must cover or exceed -55°C to 150°C

Mechanical Compatibility Criteria:

Mounting Type: Surface Mount required
Package Compatibility: Pin configuration and footprint must support direct or adapter-based substitution

The FDS4470 qualifies as a substitute based on these parameters. It exceeds the electrical specifications of the FDR4420A while maintaining surface mount compatibility.

Parameter Comparison

Parameter	FDR4420A (Main Part)	FDS4470 (Substitute)	Compatibility Notes
Manufacturer	onsemi	Fairchild Semiconductor	Different manufacturers
FET Type	N-Channel	N-Channel	Match
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	Match
Drain to Source Voltage (Vdss)	30 V	40 V	Substitute exceeds requirement
Current - Continuous Drain (Id) @ 25°C	11 A	12.5 A	Substitute exceeds requirement
Rds On (Max) @ Id, Vgs	9 mOhm @ 11A, 10V	9 mOhm @ 12.5A, 10V	Match at rated conditions
Vgs(th) (Max) @ Id	3 V @ 250µA	5 V @ 250µA	Substitute threshold higher; verify gate drive compatibility
Gate Charge (Qg) (Max) @ Vgs	33 nC @ 5V	63 nC @ 10V	Substitute gate charge higher; verify gate drive capability
Vgs (Max)	±20 V	+30 V, -20 V	Substitute positive rating higher
Input Capacitance (Ciss) (Max) @ Vds	2560 pF @ 15V	2659 pF @ 20V	Similar capacitance; substitute slightly higher
Power Dissipation (Max)	1.8 W	2.5 W	Substitute exceeds requirement
Operating Temperature Range	-55 to 150 °C (TJ)	-55 to 175 °C (TJ)	Substitute exceeds requirement
Mounting Type	Surface Mount	Surface Mount	Match
Package / Case	8-LSOP (0.130", 3.30mm Width)	8-SOIC (0.154", 3.90mm Width)	Different packages; footprint verification required
Product Status	Obsolete	Active	Substitute is in active production

Engineering Selection Recommendations

Substitution Feasibility:

The FDS4470 is electrically qualified as a substitute for the FDR4420A based on superior or equivalent electrical performance across all critical parameters. The substitute device exceeds the voltage, current, and power dissipation ratings of the main part, providing design margin for the application.

Product Status Advantage:

The FDS4470 is classified as Active, ensuring ongoing availability and supply chain support. The FDR4420A is Obsolete, making the FDS4470 the preferred choice for new designs and production continuity.

Compliance and Certification:

Both parts carry identical ECCN (EAR99) and HTSUS (8541.29.0095) classifications, confirming regulatory equivalence for export and trade purposes.

Package Consideration:

The FDR4420A uses an 8-LSOP package (0.130", 3.30mm width), while the FDS4470 uses an 8-SOIC package (0.154", 3.90mm width). These packages have different footprints. Direct PCB substitution without layout modification is not possible. A package adapter or PCB redesign is required for physical integration.

Gate Drive Verification:

The FDS4470 has a higher gate threshold voltage (5V vs. 3V) and higher gate charge (63 nC vs. 33 nC). Existing gate drive circuits must be evaluated to confirm adequate drive voltage and current capability for the substitute device.

Frequently Asked Questions (FAQ)

Q: Can the FDS4470 be used as a direct drop-in replacement for the FDR4420A?

A: The FDS4470 is electrically compatible and exceeds the electrical specifications of the FDR4420A. However, the devices use different surface mount packages (8-LSOP vs. 8-SOIC), so direct PCB substitution without layout modification is not possible. A package adapter or PCB redesign is required.

Q: What are the key electrical differences between these parts?

A: The FDS4470 exceeds the FDR4420A in drain-to-source voltage (40V vs. 30V), continuous drain current (12.5A vs. 11A), and power dissipation (2.5W vs. 1.8W). On-state resistance is equivalent at rated conditions (9 mOhm). The FDS4470 has a higher gate threshold voltage (5V vs. 3V) and higher gate charge (63 nC vs. 33 nC), which may affect gate drive circuit performance.

Q: Will my existing gate drive circuit work with the FDS4470?

A: The FDS4470 requires a higher gate threshold voltage (5V) compared to the FDR4420A (3V). Additionally, the gate charge is nearly double (63 nC vs. 33 nC). Verify that your gate drive circuit can supply sufficient voltage and current to meet the FDS4470 specifications. Inadequate gate drive may result in slower switching and increased power dissipation.

Q: Are there any thermal considerations when substituting to the FDS4470?

A: The FDS4470 has a higher maximum power dissipation rating (2.5W vs. 1.8W) and a higher maximum operating temperature (175°C vs. 150°C). These characteristics provide additional thermal margin. However, actual thermal performance depends on PCB layout, thermal management, and application duty cycle. Thermal analysis of the specific application is recommended.

Q: What is the difference between the 8-LSOP and 8-SOIC packages?

A: The 8-LSOP package (used by FDR4420A) has a width of 0.130" (3.30mm), while the 8-SOIC package (used by FDS4470) has a width of 0.154" (3.90mm). Both are 8-pin surface mount packages, but the different dimensions result in incompatible PCB footprints. Physical substitution requires either a package adapter or PCB layout modification.

Q: Is the FDS4470 available in the same package as the FDR4420A?

A: No. The FDS4470 is manufactured only in the 8-SOIC package. The FDR4420A SuperSOT™-8 package is specific to onsemi. If the original package is required, alternative N-Channel MOSFETs with equivalent electrical specifications in the SuperSOT™-8 package must be evaluated separately.

Q: What is the product status of each part?

A: The FDR4420A is Obsolete, indicating it is no longer in production. The FDS4470 is Active, meaning it is currently manufactured and supported by Fairchild Semiconductor. For new designs and ongoing production, the FDS4470 is the recommended choice.

Q: Are there any compliance or regulatory differences between these parts?

A: Both parts share identical ECCN (EAR99) and HTSUS (8541.29.0095) classifications. No regulatory or compliance differences exist between the two devices.

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