IRF7809 N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IRF7809 is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 30V drain-to-source voltage with 17.6A continuous drain current at 25°C. This device is packaged in an 8-SO surface mount configuration and belongs to the HEXFET® series. The IRF7809 is classified as obsolete, making identification of functionally equivalent substitute components necessary for ongoing design support, production continuity, and system maintenance. Substitute parts must maintain electrical compatibility across critical parameters including voltage rating, current capacity, on-resistance characteristics, and gate charge specifications.

Key Parameters

Parameter	Value	Specification Basis
Drain-to-Source Voltage (Vdss)	30 V	Maximum voltage rating
Continuous Drain Current (Id) @ 25°C	17.6 A	Thermal ambient rating
On-Resistance (Rds On Max)	7.5 mOhm @ 15A, 4.5V	Conduction loss specification
Gate Threshold Voltage (Vgs(th) Max)	1 V @ 250 µA	Gate drive requirement
Gate Charge (Qg Max)	86 nC @ 5 V	Switching speed and drive circuit design
Maximum Gate Voltage (Vgs Max)	±12 V	Gate drive voltage limit
Input Capacitance (Ciss Max)	7300 pF @ 16 V	Input impedance and switching characteristics
Power Dissipation (Max)	3.5 W	Thermal management requirement
Package Type	8-SOIC (0.154", 3.90mm Width)	PCB layout and thermal interface
Mounting Type	Surface Mount	Assembly process compatibility

Substitute Part Grouping Explanation

Substitute parts for the IRF7809 are qualified based on the following electrical and mechanical criteria:

Voltage Rating Compatibility: All substitute parts must maintain a Vdss rating of 30V or higher to ensure safe operation across the full voltage range of the original design.

Current Capacity: Substitute parts must support continuous drain current ratings of 14A or greater at 25°C ambient temperature. The IRF7809 specification of 17.6A establishes the baseline; substitutes with 14A to 16A ratings remain functionally compatible for applications where the full 17.6A capacity is not simultaneously required at maximum ambient temperature.

On-Resistance Characteristics: Rds On specifications must not exceed 7.5 mOhm at the rated gate voltage and current conditions. This parameter directly affects conduction losses and thermal performance.

Gate Drive Voltage: Substitute parts must accept gate drive voltages compatible with existing circuit designs. The IRF7809 maximum Vgs of ±12V establishes the upper limit; substitutes with ±20V ratings provide additional margin.

Switching Characteristics: Gate charge (Qg) and input capacitance (Ciss) values determine switching speed and drive circuit requirements. Substitutes with lower Qg and Ciss values indicate improved switching performance.

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

Compliance Status: RoHS3 compliance and REACH unaffected status are required for current production and regulatory adherence.

Parameter Comparison

Parameter	IRF7809 (Infineon)	FDS6682 (onsemi)	RJK0354DSP-00#J0 (Renesas)
Manufacturer	Infineon Technologies	onsemi	Renesas Electronics Corporation
FET Type	N-Channel	N-Channel	N-Channel
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)
Vdss (Drain-to-Source Voltage)	30 V	30 V	30 V
Id @ 25°C (Continuous Drain Current)	17.6 A	14 A	16 A
Rds On (Max)	7.5 mOhm @ 15A, 4.5V	7.5 mOhm @ 14A, 10V	7 mOhm @ 8A, 10V
Vgs(th) (Max) @ Id	1 V @ 250 µA	3 V @ 250 µA	Not specified
Qg (Max) @ Vgs	86 nC @ 5 V	31 nC @ 5 V	12 nC @ 4.5 V
Vgs (Max)	±12 V	±20 V	±20 V
Ciss (Max) @ Vds	7300 pF @ 16 V	2310 pF @ 15 V	1740 pF @ 10 V
Power Dissipation (Max)	3.5 W	1 W	2 W
Package / Case	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)	8-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Product Status	Obsolete	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

FDS6682 (onsemi): This substitute is electrically compatible with the IRF7809 across voltage and current parameters. The FDS6682 maintains the 30V Vdss rating and 7.5 mOhm on-resistance specification. The continuous drain current rating of 14A is lower than the IRF7809 specification of 17.6A; however, this device remains suitable for applications where peak current demand does not consistently reach 17.6A at 25°C ambient conditions. The FDS6682 demonstrates improved switching characteristics with gate charge reduced to 31 nC and input capacitance of 2310 pF, indicating faster switching performance. The device is ROHS3 compliant and carries obsolete product status, consistent with the IRF7809 lifecycle. Inventory availability is substantial at 33,860 pieces.

RJK0354DSP-00#J0 (Renesas): This substitute provides the highest level of electrical performance and regulatory compliance. The RJK0354DSP-00#J0 maintains 30V Vdss rating with 16A continuous drain current, closely matching the IRF7809 current specification. On-resistance is specified at 7 mOhm at 8A and 10V gate voltage, meeting the conduction loss requirement. Superior switching characteristics are evident with gate charge of 12 nC and input capacitance of 1740 pF, the lowest among all candidates. The device accepts ±20V gate voltage, providing additional design margin. Critically, the RJK0354DSP-00#J0 maintains active product status, ensuring long-term availability and continued manufacturer support. ROHS3 compliance and REACH unaffected status satisfy current regulatory requirements. Inventory availability is 4,150 pieces. This device is recommended for new designs and applications requiring extended product lifecycle support.

Selection Basis: Both substitute parts satisfy the core electrical requirements of 30V voltage rating and on-resistance specification. The choice between FDS6682 and RJK0354DSP-00#J0 depends on application current requirements and product lifecycle considerations. For applications where 14A to 16A continuous current is sufficient, both devices are functionally equivalent. For applications requiring the full 17.6A specification or extended product support, the RJK0354DSP-00#J0 is the preferred selection due to active product status and superior switching characteristics.

Frequently Asked Questions (FAQ)

Q: Can the FDS6682 be used as a direct replacement for the IRF7809 in all applications?

A: The FDS6682 is electrically compatible with the IRF7809 for applications where continuous drain current does not exceed 14A at 25°C ambient temperature. The 30V voltage rating and 7.5 mOhm on-resistance are maintained. Applications requiring the full 17.6A specification of the IRF7809 must evaluate whether peak current demand can be accommodated by the 14A rating of the FDS6682, considering thermal derating at elevated ambient temperatures.

Q: What are the switching performance differences between these substitute parts?

A: The RJK0354DSP-00#J0 demonstrates the fastest switching characteristics with gate charge of 12 nC and input capacitance of 1740 pF. The FDS6682 provides intermediate performance with 31 nC gate charge and 2310 pF input capacitance. The IRF7809 exhibits the slowest switching with 86 nC gate charge and 7300 pF input capacitance. Lower gate charge and input capacitance values reduce drive circuit power consumption and enable higher switching frequencies.

Q: Are all substitute parts compatible with the existing PCB layout?

A: Yes. All substitute parts use identical 8-SOIC surface mount packaging with 0.154" (3.90mm) width. PCB footprints, solder pad layouts, and thermal interface designs require no modification for substitution.

Q: What is the significance of the gate threshold voltage difference between IRF7809 and FDS6682?

A: The IRF7809 specifies Vgs(th) of 1V at 250µA, while the FDS6682 specifies 3V at the same current. This indicates the FDS6682 requires a higher gate voltage to initiate conduction. Existing gate drive circuits must be verified to ensure adequate voltage margin above the 3V threshold. The RJK0354DSP-00#J0 does not specify this parameter in the provided data.

Q: Which substitute part is recommended for new product designs?

A: The RJK0354DSP-00#J0 is recommended for new designs. This device maintains active product status, ensuring availability and manufacturer support throughout the design lifecycle. ROHS3 compliance and REACH unaffected status satisfy current regulatory requirements. Superior switching characteristics reduce drive circuit complexity and power consumption.

Q: How do power dissipation ratings affect thermal design?

A: The IRF7809 specifies 3.5W maximum power dissipation, while the FDS6682 specifies 1W and the RJK0354DSP-00#J0 specifies 2W. Lower power dissipation ratings indicate reduced thermal load on the PCB and heat sink. Applications with tight thermal constraints may benefit from the lower dissipation characteristics of the substitute parts, particularly the FDS6682.

Q: Are there any gate voltage compatibility concerns?

A: The IRF7809 accepts maximum gate voltage of ±12V. Both substitute parts accept ±20V, providing additional design margin. Existing gate drive circuits designed for ±12V operation are compatible with both substitutes, as the lower voltage is within the ±20V specification of the replacement devices.

Q: What inventory considerations should influence the selection?

A: The FDS6682 has substantial inventory availability at 33,860 pieces, supporting high-volume production requirements. The RJK0354DSP-00#J0 has 4,150 pieces available. For applications requiring immediate large-quantity procurement, the FDS6682 may offer supply chain advantages. For long-term production, the active product status of the RJK0354DSP-00#J0 ensures continued availability beyond current inventory levels.

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