STW20NB50 Equivalent & Substitute Parts

Part Overview

The STW20NB50 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 500V drain-to-source voltage with 20A continuous drain current at 25°C. This device is packaged in TO-247-3 through-hole configuration and is part of the PowerMESH™ series. The STW20NB50 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and component procurement.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	20	A
On-State Resistance (Rds On) @ 10A, 10V	250	mOhm
Gate Threshold Voltage (Vgs(th)) @ 250µA	5	V
Gate Charge (Qg) @ 10V	110	nC
Power Dissipation (Max)	250	W
Operating Temperature (TJ)	150	°C
Package Type	TO-247-3	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitution of the STW20NB50 is determined by the following critical parameters:

Primary Matching Criteria:

Drain-to-Source Voltage (Vdss): 500V minimum
Continuous Drain Current (Id): 20A or greater at 25°C
Package Type: TO-247-3 through-hole configuration
FET Type: N-Channel MOSFET technology

Secondary Compatibility Factors:

On-State Resistance (Rds On): Lower or equivalent values ensure thermal performance
Gate Charge (Qg): Lower values reduce switching losses
Power Dissipation capability: Minimum 250W at case temperature
Operating Temperature range: Support for 150°C junction temperature

The substitute parts listed below meet the primary matching criteria. Variations in secondary parameters reflect different design approaches and manufacturing technologies while maintaining functional equivalence within the specified voltage and current ratings.

Parameter Comparison

Parameter	STW20NB50	APT20F50B	IPW50R250CPFKSA1	SPW20N60C3FKSA1	Unit
Manufacturer	STMicroelectronics	Microsemi Corporation	Infineon Technologies	Infineon Technologies	—
Drain to Source Voltage (Vdss)	500	500	500	650	V
Continuous Drain Current (Id) @ 25°C	20	20	13	20.7	A
On-State Resistance (Rds On)	250 @ 10A, 10V	300 @ 10A, 10V	250 @ 7.8A, 10V	190 @ 13.1A, 10V	mOhm
Gate Threshold Voltage (Vgs(th))	5 @ 250µA	5 @ 500µA	3.5 @ 520µA	3.9 @ 1mA	V
Gate Charge (Qg) @ 10V	110	75	36	114	nC
Power Dissipation (Max)	250	290	114	208	W
Operating Temperature (TJ)	150	-55 to 150	-55 to 150	-55 to 150	°C
Package Type	TO-247-3	TO-247-3	TO-247-3	TO-247-3	—
Product Status	Obsolete	Active	Active	Active	—
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

APT20F50B (Microsemi Corporation)

The APT20F50B provides direct functional equivalence to the STW20NB50 with matching 500V/20A ratings. This device is in active production status and carries ROHS3 compliance certification. The APT20F50B exhibits slightly higher on-state resistance (300 mOhm versus 250 mOhm) and lower gate charge (75 nC versus 110 nC), resulting in reduced switching losses. The extended operating temperature range (-55°C to 150°C) provides additional thermal margin. This substitute is suitable for applications requiring direct pin-compatible replacement with modern compliance certifications.

IPW50R250CPFKSA1 (Infineon Technologies)

The IPW50R250CPFKSA1 is a CoolMOS™ technology device rated for 500V operation with 13A continuous drain current. This part does not meet the 20A current requirement of the STW20NB50 and is suitable only for applications where the actual current demand is 13A or lower. The device offers superior on-state resistance (250 mOhm at 7.8A) and significantly lower gate charge (36 nC), making it advantageous for high-frequency switching applications. ROHS3 compliance and active product status support long-term availability. This substitute requires thermal and current capacity verification before implementation.

SPW20N60C3FKSA1 (Infineon Technologies)

The SPW20N60C3FKSA1 is a CoolMOS™ technology device with 650V drain-to-source voltage rating and 20.7A continuous drain current, exceeding the STW20NB50 specifications. This part is suitable for applications where higher voltage margin is required or where the STW20NB50 is used below its maximum voltage rating. The device demonstrates superior on-state resistance (190 mOhm at 13.1A) and active product status with ROHS3 compliance. The higher voltage rating introduces no functional incompatibility in 500V applications. This substitute is appropriate for designs requiring enhanced voltage headroom or where component standardization across multiple voltage classes is beneficial.

Frequently Asked Questions (FAQ)

Q: Can the APT20F50B directly replace the STW20NB50 in existing designs?

A: Yes. The APT20F50B matches the STW20NB50 in voltage rating (500V), current rating (20A), and package configuration (TO-247-3). Pin compatibility is maintained. The slightly higher on-state resistance (300 mOhm versus 250 mOhm) results in marginally higher conduction losses, which must be evaluated within the thermal design of the specific application.

Q: Why does the IPW50R250CPFKSA1 have a lower current rating than the STW20NB50?

A: The IPW50R250CPFKSA1 is rated for 13A continuous drain current at 25°C, compared to 20A for the STW20NB50. This reflects different die design and thermal management characteristics. The IPW50R250CPFKSA1 is suitable only for applications where the actual operating current does not exceed 13A.

Q: Is the SPW20N60C3FKSA1 suitable for 500V applications?

A: Yes. The SPW20N60C3FKSA1 is rated for 650V drain-to-source voltage, which exceeds the 500V requirement of the STW20NB50. Operating this device at 500V provides additional voltage margin and does not introduce functional incompatibility. The higher voltage rating does not degrade performance in lower-voltage applications.

Q: What is the significance of the gate charge differences among these parts?

A: Gate charge (Qg) determines the energy required to switch the transistor on and off. Lower gate charge reduces switching losses and allows higher switching frequencies. The IPW50R250CPFKSA1 exhibits the lowest gate charge (36 nC), making it advantageous for high-frequency applications. The STW20NB50 and SPW20N60C3FKSA1 have higher gate charges (110 nC and 114 nC respectively), which may increase switching losses in high-frequency designs.

Q: Are all substitute parts RoHS compliant?

A: The STW20NB50 is RoHS non-compliant. All three substitute parts (APT20F50B, IPW50R250CPFKSA1, and SPW20N60C3FKSA1) are ROHS3 compliant, meeting current environmental and regulatory requirements for new designs and procurement.

Q: Can these parts be used interchangeably in the same circuit board layout?

A: All substitute parts use the TO-247-3 package with identical pin configuration and through-hole mounting. Board layout compatibility is maintained. However, thermal design considerations may differ due to variations in power dissipation ratings and on-state resistance characteristics.

Q: What is the difference between the TO-247-3 and TO-247 [B] package designations?

A: The APT20F50B is specified with TO-247 [B] package designation, while other parts use TO-247-3. These designations refer to the same physical package with identical pin configuration and mounting characteristics. The bracketed [B] notation indicates a specific variant within the TO-247 family. Mechanical and electrical compatibility is maintained.

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