IRF7842TR N-Channel MOSFET 40V 18A Equivalent & Substitute Parts

Part Overview

The IRF7842TR is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 40V drain-to-source voltage with 18A continuous drain current at 25°C. This device is housed in an 8-SOIC surface mount package and is part of the HEXFET® series. The IRF7842TR is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and component procurement. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating the same or compatible package footprints.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	40	V
Continuous Drain Current (Id) @ 25°C	18	A (Ta)
Rds On (Max) @ 17A, 10V	5	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	2.25	V (Max)
Power Dissipation (Max)	2.5	W (Ta)
Operating Temperature Range	-55 to 150	°C (TJ)
Package / Case	8-SOIC (0.154", 3.90mm Width)	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitute parts for the IRF7842TR are identified based on strict electrical and mechanical parameter matching within the N-Channel MOSFET category. The substitution criteria are:

Primary Matching Parameters:

Drain-to-Source Voltage (Vdss): 40V minimum
N-Channel topology
Surface mount 8-SOIC package footprint compatibility
Operating temperature range: -55°C to 150°C (TJ)
Gate voltage rating: ±20V

Secondary Compatibility Parameters:

Continuous drain current rating at or above 18A
On-resistance (Rds On) at specified gate voltage
Gate threshold voltage within acceptable switching range
Package dimensions: 8-SOIC (0.154", 3.90mm Width)

Two substitute parts are identified:

IRF7842TRPBF (Infineon Technologies): Parametric equivalent with identical electrical specifications. This part maintains all core parameters of the original IRF7842TR while offering active product status and improved compliance certification (ROHS3 Compliant vs. RoHS non-compliant).

SI4456DY-T1-E3 (Vishay Siliconix): Manufacturer-recommended substitute with enhanced current rating (33A vs. 18A) and improved on-resistance (3.8mOhm vs. 5mOhm). This part provides superior thermal performance and higher current capacity within the same voltage class and package footprint.

Parameter Comparison

Parameter	IRF7842TR (Main)	IRF7842TRPBF (Parametric Equivalent)	SI4456DY-T1-E3 (MFR Recommended)
Manufacturer	Infineon Technologies	Infineon Technologies	Vishay Siliconix
FET Type	N-Channel	N-Channel	N-Channel
Vdss	40 V	40 V	40 V
Continuous Drain Current (Id) @ 25°C	18 A (Ta)	18 A (Ta)	33 A (Tc)
Rds On (Max) @ 10V	5 mOhm @ 17A	5 mOhm @ 17A	3.8 mOhm @ 20A
Vgs(th) (Max) @ 250µA	2.25 V	2.25 V	2.8 V
Gate Charge (Qg) @ Vgs	50 nC @ 4.5 V	50 nC @ 4.5 V	122 nC @ 10 V
Vgs (Max)	±20 V	±20 V	±20 V
Input Capacitance (Ciss) @ 20V	4500 pF	4500 pF	5670 pF
Power Dissipation (Max)	2.5 W (Ta)	2.5 W (Ta)	3.5 W (Ta), 7.8 W (Tc)
Operating Temperature	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)
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	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

IRF7842TRPBF Selection Criteria:

The IRF7842TRPBF is the direct parametric equivalent of the IRF7842TR, maintaining identical electrical specifications including 40V Vdss, 18A continuous drain current, and 5mOhm on-resistance. This part is classified as active product status, ensuring long-term availability and supply chain stability. The IRF7842TRPBF carries ROHS3 compliance certification, addressing regulatory requirements that the original IRF7842TR does not meet. This substitute is appropriate for applications requiring exact electrical performance matching and where component availability from the original manufacturer is no longer feasible.

SI4456DY-T1-E3 Selection Criteria:

The SI4456DY-T1-E3 is designated as the manufacturer-recommended substitute and provides enhanced electrical performance within the same voltage class and package footprint. This part delivers 33A continuous drain current (versus 18A) and superior on-resistance of 3.8mOhm (versus 5mOhm), resulting in reduced power dissipation and improved thermal efficiency. The SI4456DY-T1-E3 is active product status with ROHS3 compliance. This substitute is appropriate for applications where improved thermal performance, higher current capacity, or enhanced efficiency is beneficial, provided that the increased gate charge (122nC versus 50nC) and input capacitance (5670pF versus 4500pF) are compatible with the circuit's gate drive architecture.

Both substitutes maintain the same 8-SOIC package footprint and operating temperature range, enabling direct PCB layout compatibility without redesign.

Frequently Asked Questions (FAQ)

Q: Can IRF7842TRPBF be used as a direct replacement for IRF7842TR?

A: Yes. The IRF7842TRPBF is a parametric equivalent with identical electrical specifications. Both parts share the same Vdss (40V), continuous drain current (18A), on-resistance (5mOhm @ 17A, 10V), and package footprint (8-SOIC). The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 versus non-compliant). No circuit modifications are required.

Q: What are the advantages of using SI4456DY-T1-E3 over IRF7842TRPBF?

A: The SI4456DY-T1-E3 offers higher continuous drain current (33A versus 18A) and lower on-resistance (3.8mOhm versus 5mOhm), resulting in reduced power dissipation and improved thermal performance. However, the SI4456DY-T1-E3 has higher gate charge (122nC versus 50nC) and input capacitance (5670pF versus 4500pF), which may require gate drive circuit evaluation to ensure adequate switching speed and efficiency.

Q: Are all three parts pin-compatible?

A: Yes. All three parts (IRF7842TR, IRF7842TRPBF, and SI4456DY-T1-E3) use the 8-SOIC package with identical pin assignments and footprint dimensions (0.154", 3.90mm Width). Direct PCB substitution is possible without layout modifications.

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

A: Ta refers to ambient temperature, while Tc refers to case temperature. The IRF7842TR and IRF7842TRPBF specify power dissipation at Ta (2.5W), whereas the SI4456DY-T1-E3 provides ratings at both Ta (3.5W) and Tc (7.8W). For thermal design, use the appropriate rating based on your measurement point and thermal management approach.

Q: Is the SI4456DY-T1-E3 suitable for applications originally designed for 18A operation?

A: Yes. The SI4456DY-T1-E3 is rated for 33A continuous drain current, which exceeds the 18A requirement of the original design. The part operates within the same 40V voltage class and maintains compatibility with the 8-SOIC package. The higher current rating provides design margin and improved thermal performance. Gate drive circuit compatibility should be verified due to increased gate charge.

Q: What compliance certifications apply to each part?

A: The IRF7842TR is RoHS non-compliant. Both IRF7842TRPBF and SI4456DY-T1-E3 are ROHS3 compliant. All three parts are REACH unaffected and classified under ECCN EAR99. For applications requiring RoHS compliance, use IRF7842TRPBF or SI4456DY-T1-E3.

Q: Can I use these parts interchangeably in high-frequency switching applications?

A: Electrical interchangeability depends on gate drive circuit design. The IRF7842TRPBF is a direct replacement with identical gate charge (50nC). The SI4456DY-T1-E3 has significantly higher gate charge (122nC), which may affect switching frequency and efficiency. Verify that your gate drive circuit can supply the required charge within the desired switching period before selecting the SI4456DY-T1-E3 for high-frequency applications.

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