2SK4124 Equivalent & Substitute Parts

Part Overview

The 2SK4124 is an N-Channel MOSFET manufactured by onsemi, rated for 500V drain-to-source voltage with a continuous drain current of 20A at 25°C. The device is housed in a TO-3PB package and is designed for through-hole mounting applications requiring high-voltage switching capability.

The 2SK4124 is classified as an obsolete product. Identifying equivalent and substitute parts is necessary to support ongoing maintenance, repair, and redesign of legacy systems that originally incorporated this component.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Technology	MOSFET (Metal Oxide)	—
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	20	A
Drive Voltage (Max Rds On)	10	V
Rds On (Max) @ Id, Vgs	430	mOhm @ 8A, 10V
Gate Charge (Qg) (Max) @ Vgs	46.6	nC @ 10V
Vgs (Max)	±30	V
Input Capacitance (Ciss) (Max) @ Vds	1200	pF @ 30V
Power Dissipation (Max)	2.5 (Ta), 170 (Tc)	W
Operating Temperature (TJ)	150	°C
Mounting Type	Through Hole	—
Package / Case	TO-3P-3, SC-65-3	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—
REACH Status	REACH Unaffected	—

Substitute Part Grouping Explanation

Substitution of the 2SK4124 is determined by strict alignment of the following electrical and mechanical parameters:

Critical Substitution Parameters:

FET Type: N-Channel topology
Technology: MOSFET (Metal Oxide)
Drain to Source Voltage (Vdss): 500V minimum
Mounting Type: Through Hole
Package Compatibility: TO-3P or TO-3PB footprint

Performance Parameters:

Continuous Drain Current (Id): Must support the application's current requirements
On-State Resistance (Rds On): Lower values indicate improved efficiency
Gate Charge (Qg): Affects switching speed and driver requirements
Input Capacitance (Ciss): Influences gate drive circuit design

The FQA13N50C-F109 qualifies as a substitute based on matching voltage rating (500V Vdss), N-Channel topology, MOSFET technology, through-hole mounting, and compatible TO-3P package. However, the continuous drain current rating differs: the FQA13N50C-F109 is rated at 13.5A (Tc) compared to the 2SK4124's 20A (Ta). This difference requires application-level evaluation to determine suitability.

Parameter Comparison

Parameter	2SK4124	FQA13N50C-F109	Unit
Manufacturer	onsemi	onsemi	—
FET Type	N-Channel	N-Channel	—
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	—
Drain to Source Voltage (Vdss)	500	500	V
Continuous Drain Current (Id) @ 25°C	20 (Ta)	13.5 (Tc)	A
Drive Voltage (Max Rds On)	10	10	V
Rds On (Max) @ Id, Vgs	430 @ 8A, 10V	480 @ 6.75A, 10V	mOhm
Gate Charge (Qg) (Max) @ Vgs	46.6 @ 10V	56 @ 10V	nC
Vgs (Max)	±30	±30	V
Input Capacitance (Ciss) (Max) @ Vds	1200 @ 30V	2055 @ 25V	pF
Power Dissipation (Max)	2.5 (Ta), 170 (Tc)	218 (Tc)	W
Operating Temperature (TJ)	150	-55 ~ 150	°C
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-3P-3, SC-65-3	TO-3P-3, SC-65-3	—
Product Status	Obsolete	Obsolete	—
REACH Status	REACH Unaffected	REACH Unaffected	—

Engineering Selection Recommendations

Both the 2SK4124 and FQA13N50C-F109 are classified as obsolete products and share identical REACH compliance status (REACH Unaffected). Both devices are manufactured by onsemi and employ N-Channel MOSFET technology with 500V voltage ratings.

The primary distinction between these parts is the continuous drain current specification. The 2SK4124 supports 20A (Ta), while the FQA13N50C-F109 supports 13.5A (Tc). Selection between these devices depends on whether the application's current requirements fall within the FQA13N50C-F109's 13.5A rating. If the application requires the full 20A capability of the original 2SK4124, the FQA13N50C-F109 is not suitable as a direct substitute.

Both devices feature compatible TO-3P package footprints and through-hole mounting, enabling mechanical interchangeability. The FQA13N50C-F109 exhibits higher input capacitance (2055 pF vs. 1200 pF) and slightly higher gate charge (56 nC vs. 46.6 nC), which may affect gate drive circuit performance.

Frequently Asked Questions (FAQ)

Q: Can the FQA13N50C-F109 directly replace the 2SK4124 in all applications?

A: Direct replacement is limited by current rating. The FQA13N50C-F109 is rated for 13.5A continuous drain current, while the 2SK4124 is rated for 20A. If the application operates at or above 13.5A, the FQA13N50C-F109 cannot serve as a substitute. Applications operating below 13.5A may use the FQA13N50C-F109, provided all other electrical parameters are acceptable.

Q: Are the packages physically compatible?

A: Yes. Both devices use TO-3P-3 and SC-65-3 package designations and are mounted through-hole. Physical footprint compatibility is confirmed.

Q: What is the significance of the different current measurement conditions (Ta vs. Tc)?

A: The 2SK4124 specifies continuous drain current at Ta (ambient temperature), while the FQA13N50C-F109 specifies it at Tc (case temperature). These represent different measurement methodologies and affect how the current ratings should be interpreted in thermal design calculations.

Q: How do the gate charge differences affect circuit design?

A: The FQA13N50C-F109 has higher gate charge (56 nC vs. 46.6 nC). This requires the gate driver to supply more charge per switching cycle, potentially increasing switching losses and driver power dissipation. Gate driver circuits must be evaluated for compatibility with the higher charge requirement.

Q: Are both devices compliant with current environmental regulations?

A: Yes. Both the 2SK4124 and FQA13N50C-F109 are REACH Unaffected, indicating compliance with REACH regulations. The FQA13N50C-F109 is additionally RoHS3 Compliant.

Q: What is the operating temperature range for each device?

A: The 2SK4124 specifies a maximum junction temperature (TJ) of 150°C without a stated minimum. The FQA13N50C-F109 specifies an operating temperature range of -55°C to 150°C (TJ), providing a defined lower temperature limit.

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