STF40N20 N-Channel MOSFET 200V 40A Equivalent & Substitute Parts

Part Overview

The STF40N20 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 200V drain-to-source voltage and 40A continuous drain current in a Through Hole TO-220FP package. This device is part of the STripFET™ series and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	200	V
Current - Continuous Drain (Id) @ 25°C	40	A (Tc)
Rds On (Max) @ Id, Vgs	45	mOhm @ 20A, 10V
Gate Charge (Qg) (Max) @ Vgs	75	nC @ 10V
Vgs (Max)	±20	V
Input Capacitance (Ciss) (Max) @ Vds	2500	pF @ 25V
Power Dissipation (Max)	40	W (Tc)
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-220-3 Full Pack	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the STF40N20 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Drain to Source Voltage (Vdss): Must equal or exceed 200V
FET Type: Must be N-Channel
Technology: Must be MOSFET (Metal Oxide)
Operating Temperature Range: Must support -55°C to 150°C (TJ)
Gate Voltage (Vgs Max): Must support ±20V or greater

Mechanical Compatibility Criteria:

Mounting Type: Must be Through Hole
Package / Case: Must be TO-220-3 Full Pack or compatible TO-220 variant

Regulatory Compliance:

RoHS Status: Must be ROHS3 Compliant
REACH Status: Must be REACH Unaffected

Substitute parts are classified into two categories: Direct Equivalents (identical electrical specifications) and Similar Parts (enhanced or alternative specifications within acceptable operating parameters).

Parameter Comparison

Parameter	STF40N20	STF40NF20	RCX700N20
Manufacturer	STMicroelectronics	STMicroelectronics	Rohm Semiconductor
Product Status	Obsolete	Active	Active
FET Type	N-Channel	N-Channel	N-Channel
Drain to Source Voltage (Vdss)	200V	200V	200V
Current - Continuous Drain (Id) @ 25°C	40A (Tc)	40A (Tc)	70A (Tc)
Rds On (Max) @ Id, Vgs	45 mOhm @ 20A, 10V	45 mOhm @ 20A, 10V	42.7 mOhm @ 35A, 10V
Gate Charge (Qg) (Max) @ Vgs	75 nC @ 10V	75 nC @ 10V	125 nC @ 10V
Vgs (Max)	±20V	±20V	±30V
Input Capacitance (Ciss) (Max) @ Vds	2500 pF @ 25V	2500 pF @ 25V	6900 pF @ 25V
Power Dissipation (Max)	40W (Tc)	40W (Tc)	40W (Tc)
Operating Temperature	-55 to 150°C (TJ)	-55 to 150°C (TJ)	150°C (TJ)
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	TO-220-3 Full Pack	TO-220-3 Full Pack	TO-220-3 Full Pack
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Inventory Status	1040 Pcs New Original In Stock	1330 Pcs New Original In Stock	966 Pcs New Original In Stock

Engineering Selection Recommendations

STF40NF20 (Direct Equivalent)

The STF40NF20 is the primary substitute for the obsolete STF40N20. Both devices share identical electrical specifications: 200V Vdss, 40A continuous drain current, 45 mOhm Rds(on), 75 nC gate charge, and ±20V gate voltage rating. The STF40NF20 maintains the same operating temperature range (-55°C to 150°C TJ) and package configuration (TO-220-3 Full Pack). The critical distinction is product status: STF40NF20 is Active, ensuring long-term availability and supply chain continuity. Both devices are ROHS3 Compliant and REACH Unaffected. The STF40NF20 is packaged in Tube format, whereas the STF40N20 was supplied in standard packaging. This direct equivalent is suitable for one-to-one replacement in all applications where the STF40N20 was originally specified.

RCX700N20 (Similar Part - Enhanced Current Rating)

The RCX700N20 manufactured by Rohm Semiconductor is a similar part that shares the same 200V Vdss rating and Through Hole TO-220-3 Full Pack configuration. This device offers enhanced continuous drain current of 70A (Tc) compared to the 40A rating of the STF40N20, with a slightly lower Rds(on) of 42.7 mOhm @ 35A, 10V. The RCX700N20 features an extended gate voltage rating of ±30V and higher input capacitance of 6900 pF @ 25V. Gate charge is higher at 125 nC @ 10V. The RCX700N20 is Active and ROHS3 Compliant. The higher current rating and lower on-resistance make this part suitable for applications requiring improved thermal performance or higher current handling. However, the increased gate charge and input capacitance may affect switching characteristics in gate-drive-limited circuits. Selection of RCX700N20 requires confirmation that the application can accommodate these parameter differences.

Frequently Asked Questions (FAQ)

Q: Can STF40NF20 be used as a direct replacement for STF40N20?

A: Yes. The STF40NF20 is a direct electrical and mechanical equivalent. Both devices have identical Vdss (200V), Id (40A), Rds(on) (45 mOhm), gate charge (75 nC), and operating temperature range (-55°C to 150°C TJ). Both are packaged in TO-220-3 Full Pack and are ROHS3 Compliant. The primary advantage of STF40NF20 is its Active product status, ensuring continued availability.

Q: What are the key differences between STF40N20 and RCX700N20?

A: Both devices share 200V Vdss and TO-220-3 Full Pack configuration. The RCX700N20 offers higher continuous drain current (70A vs. 40A), lower Rds(on) (42.7 mOhm vs. 45 mOhm), higher gate voltage rating (±30V vs. ±20V), and higher input capacitance (6900 pF vs. 2500 pF). Gate charge is higher in RCX700N20 (125 nC vs. 75 nC). These differences affect thermal performance and switching behavior.

Q: Is the RCX700N20 suitable for all applications using STF40N20?

A: The RCX700N20 is electrically compatible for applications where the 200V Vdss and Through Hole TO-220 mounting are required. However, the higher gate charge and input capacitance may require gate-drive circuit adjustments. The enhanced current rating makes it suitable for applications requiring improved thermal margin or higher current handling. Application-specific validation is necessary.

Q: Are all substitute parts ROHS3 Compliant?

A: Yes. Both STF40NF20 and RCX700N20 are ROHS3 Compliant and REACH Unaffected, matching the regulatory status of the original STF40N20.

Q: What is the difference between TO-220FP and TO-220FM packages?

A: Both are Through Hole TO-220-3 Full Pack variants. TO-220FP (STF40N20 and STF40NF20) and TO-220FM (RCX700N20) are mechanically compatible in standard TO-220 footprints. The designations reflect manufacturer-specific package nomenclature but do not affect PCB layout or mounting compatibility.

Q: Why is STF40N20 listed as Obsolete?

A: The STF40N20 has reached end-of-life status. STMicroelectronics has transitioned to the STF40NF20 as the active replacement. The STF40NF20 provides identical electrical performance with the benefit of ongoing manufacturing and supply chain support.

Q: Can gate-drive circuits designed for STF40N20 be used with RCX700N20 without modification?

A: Gate-drive circuits may require adjustment. The RCX700N20 has higher gate charge (125 nC vs. 75 nC) and input capacitance (6900 pF vs. 2500 pF). These parameters affect gate-drive current requirements and switching speed. Circuits with limited gate-drive capability may experience slower switching transitions. Circuit analysis is required to confirm compatibility.

Q: What inventory levels are available for each part?

A: STF40N20 has 1040 Pcs in stock, STF40NF20 has 1330 Pcs in stock, and RCX700N20 has 966 Pcs in stock. All are listed as New Original In Stock.

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