IRF7420 P-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IRF7420 is a P-Channel MOSFET manufactured by Infineon Technologies, rated for 12V drain-to-source voltage with 11.5A continuous drain current. This device is part of the HEXFET® series and is designed for surface mount applications in 8-SO packaging. The IRF7420 is classified as obsolete, making identification of functionally equivalent substitute components essential for ongoing design support, production continuity, and system maintenance.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	12	V
Continuous Drain Current (Id) @ 25°C	11.5	A
On-Resistance (Rds On Max) @ 11.5A, 4.5V	14	mOhm
Gate Threshold Voltage (Vgs(th) Max) @ 250µA	900	mV
Gate Charge (Qg Max) @ 4.5V	38	nC
Power Dissipation (Max)	2.5	W
Operating Temperature Range	-55 to 150	°C
Package Type	8-SOIC	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution of the IRF7420 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Must be ≥12V to maintain voltage rating compatibility
Continuous Drain Current (Id): Must be ≥11.5A to support the same current-handling capacity
On-Resistance (Rds On): Lower or equivalent values ensure thermal performance and efficiency
Gate Threshold Voltage (Vgs(th)): Must be compatible with existing gate drive circuits
Package and Mounting: 8-SOIC surface mount package with 0.154" (3.90mm) width for PCB compatibility
Channel Type: P-Channel configuration is mandatory

Substitution Logic: Parts are grouped into two categories based on voltage rating:

12V Rated Substitutes: Direct voltage-class replacements maintaining the original 12V Vdss specification
20V Rated Substitutes: Higher voltage-rated alternatives that operate within the 12V application envelope while providing enhanced voltage margin and improved thermal characteristics

All substitute parts maintain P-Channel MOSFET technology, 8-SOIC packaging, and surface mount configuration. Electrical parameters are compared within each voltage class to ensure functional equivalence.

Parameter Comparison

Parameter	IRF7420 (Main)	AO4437L	FDS6375	FDS6575	FDS6576	Unit
Manufacturer	Infineon	Alpha & Omega	onsemi	onsemi	onsemi	—
Vdss	12	12	20	20	20	V
Id @ 25°C	11.5	11	8	10	11	A
Rds On (Max) @ rated Id, 4.5V	14	16	24	13	14	mOhm
Vgs(th) Max @ 250µA	900	1000	1500	1500	1500	mV
Qg Max @ 4.5V	38	47	36	74	60	nC
Ciss Max @ specified Vds	3529 @ 10V	4750 @ 6V	2694 @ 10V	4951 @ 10V	4044 @ 10V	pF
Power Dissipation (Max)	2.5	3	2.5	2.5	2.5	W
Operating Temperature	-55 to 150	-55 to 150	-55 to 175	-55 to 175	-55 to 150	°C
Package	8-SOIC	8-SOIC	8-SOIC	8-SOIC	8-SOIC	—
Product Status	Obsolete	Active	Active	Active	Active	—
RoHS Compliance	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

12V Voltage Class Substitute:

AO4437L (Alpha & Omega Semiconductor Inc.) is the direct voltage-class equivalent to the IRF7420. This part maintains the 12V Vdss rating and delivers 11A continuous drain current, closely matching the original 11.5A specification. The AO4437L is currently in active production status, ensuring long-term availability and supply chain stability. This device is ROHS3 compliant, addressing regulatory requirements that the obsolete IRF7420 does not meet. The 16mOhm on-resistance is slightly higher than the IRF7420's 14mOhm, resulting in marginally increased power dissipation under identical operating conditions. Gate threshold voltage is 1V, requiring minimal adjustment to existing gate drive circuits designed for the 900mV IRF7420 threshold. The AO4437L is recommended for applications requiring direct form-factor and voltage-rating compatibility with minimal circuit redesign.

20V Voltage Class Substitutes:

The onsemi PowerTrench® series devices (FDS6375, FDS6575, FDS6576) operate at 20V Vdss, providing enhanced voltage margin while remaining fully functional in 12V applications. These parts are active production items with ROHS3 compliance.

FDS6575 delivers 10A continuous drain current with 13mOhm on-resistance, offering superior thermal performance compared to the IRF7420. The lower on-resistance reduces power dissipation and heat generation. Operating temperature extends to 175°C, exceeding the IRF7420's 150°C maximum. Gate charge of 74nC is elevated, requiring consideration in high-frequency switching applications.

FDS6576 provides 11A continuous drain current with 14mOhm on-resistance, matching the IRF7420's on-resistance specification exactly. This device delivers equivalent electrical performance with the added benefit of 20V voltage rating and active production status. Gate charge of 60nC is moderate. Operating temperature range matches the IRF7420 at -55°C to 150°C.

FDS6375 is rated for 8A continuous drain current, below the IRF7420's 11.5A specification. This part is suitable only for applications where drain current requirements do not exceed 8A. The 24mOhm on-resistance is significantly higher, resulting in increased power dissipation. This device is not recommended as a direct substitute for full-current applications.

Compliance and Availability:

All substitute parts are ROHS3 compliant and currently in active production. Inventory availability is confirmed for all recommended alternatives. The IRF7420's obsolete status and non-compliance with modern regulatory standards make transition to an active substitute essential for new designs and long-term production support.

Frequently Asked Questions (FAQ)

Q: Can the AO4437L directly replace the IRF7420 without circuit modifications?

A: The AO4437L is mechanically and electrically compatible with the IRF7420 in most applications. Both devices use 8-SOIC packaging and maintain 12V Vdss rating. The gate threshold voltage difference (1V vs. 900mV) is within typical gate drive circuit tolerance. However, circuit validation is required to confirm performance in specific applications, particularly in high-frequency switching or marginal gate drive voltage conditions.

Q: Why are 20V-rated devices (FDS6575, FDS6576) listed as substitutes for a 12V application?

A: P-Channel MOSFETs rated for higher drain-to-source voltages operate safely at lower voltages. A 20V-rated device in a 12V application experiences reduced electrical stress and improved reliability margins. The 20V devices provide identical or superior on-resistance, lower power dissipation, and extended temperature operating ranges. These characteristics make them suitable substitutes while offering design advantages.

Q: What is the impact of higher gate threshold voltage in substitute parts?

A: The AO4437L and 20V onsemi devices have gate threshold voltages of 1V to 1.5V, compared to the IRF7420's 900mV. This requires slightly higher gate drive voltage to achieve full on-state conduction. Existing gate drive circuits designed for the IRF7420 typically operate at 4.5V to 5V, which is sufficient to drive the substitute parts into full conduction. Applications with marginal gate drive voltage (below 3V) may require circuit adjustment.

Q: How does on-resistance affect thermal performance?

A: On-resistance (Rds On) directly determines power dissipation in the conducting state: P = I²R. Lower on-resistance reduces heat generation. The FDS6575 (13mOhm) dissipates less heat than the IRF7420 (14mOhm) at identical current levels. The AO4437L (16mOhm) dissipates slightly more heat. In thermally constrained applications, lower on-resistance devices improve reliability and reduce cooling requirements.

Q: Are all substitute parts available in the same packaging?

A: Yes. All substitute parts are supplied in 8-SOIC (0.154", 3.90mm width) surface mount packaging, identical to the IRF7420. PCB footprints are directly compatible without layout modifications.

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

A: Gate charge affects switching speed and gate drive power requirements. Higher gate charge (FDS6575 at 74nC) requires more charge transfer from the gate driver, potentially increasing switching losses in high-frequency applications. Lower gate charge (FDS6375 at 36nC) reduces gate drive power. The IRF7420 at 38nC is comparable to FDS6375. For applications switching below 100kHz, gate charge differences are typically negligible.

Q: Why is the IRF7420 classified as obsolete?

A: The IRF7420 is no longer manufactured by Infineon Technologies. Obsolete status indicates end-of-life designation and unavailability from primary sources. Remaining inventory is limited and sourcing becomes increasingly difficult. Transition to active production alternatives ensures long-term design support and supply chain reliability.

Q: Does RoHS compliance affect electrical performance?

A: RoHS compliance (ROHS3) indicates the device meets environmental and regulatory standards for hazardous substance restrictions. Compliance does not alter electrical performance but is mandatory for applications in regulated markets and industries. The IRF7420's non-compliance status may restrict its use in new designs subject to RoHS requirements.

Q: Can FDS6375 be used in applications requiring 11.5A continuous current?

A: No. The FDS6375 is rated for 8A maximum continuous drain current, which is below the IRF7420's 11.5A specification. Operating this device above its rated current causes excessive heat generation, reduced reliability, and potential device failure. FDS6375 is suitable only for applications with drain current requirements not exceeding 8A.

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