STS15N4LLF5 Equivalent & Substitute Parts

Part Overview

The STS15N4LLF5 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 40V drain-to-source voltage with 15A continuous drain current at 25°C. This device is part of the STripFET™ V series and is housed in an 8-SOIC surface mount package. The part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	40	V
Continuous Drain Current (Id) @ 25°C	15	A (Tc)
Rds On (Max) @ 7.5A, 10V	6.7	mOhm
Gate Charge (Qg) @ 4.5V	12.9	nC
Input Capacitance (Ciss) @ 25V	1570	pF
Power Dissipation (Max)	3	W (Tc)
Operating Temperature Range	-55 to 150	°C (TJ)
Package	8-SOIC	Surface Mount
Vgs (Max)	±16	V

Substitute Part Grouping Explanation

Substitution of the STS15N4LLF5 is determined by the following critical parameters:

Mandatory Matching Parameters:

Drain to Source Voltage (Vdss): 40V
Package Type: 8-SOIC surface mount
FET Type: N-Channel MOSFET
Technology: Metal Oxide

Performance Parameters for Compatibility:

Continuous Drain Current (Id): Substitute must meet or exceed 15A
Rds On (Max): Lower or equal values indicate improved performance
Gate Charge (Qg): Lower values reduce switching losses
Operating Temperature Range: Must support -55°C to 150°C minimum
Power Dissipation: Must support thermal requirements of the application

All substitute parts listed maintain the 40V Vdss rating and 8-SOIC package format. Variations in drain current, on-resistance, and gate charge reflect different device architectures and manufacturing processes from alternative suppliers.

Parameter Comparison

Parameter	STS15N4LLF5	IRF7842TRPBF	FDS8842NZ	FDS4470	FDS4672A	IRF7470TRPBF
Manufacturer	STMicroelectronics	Infineon Technologies	onsemi	Fairchild Semiconductor	onsemi	International Rectifier
Vdss (V)	40	40	40	40	40	40
Id @ 25°C (A)	15 (Tc)	18 (Ta)	14.9 (Ta)	12.5 (Ta)	11 (Ta)	10 (Ta)
Rds On (Max) (mOhm)	6.7 @ 7.5A, 10V	5 @ 17A, 10V	7 @ 14.9A, 10V	9 @ 12.5A, 10V	13 @ 11A, 4.5V	13 @ 10A, 10V
Gate Charge (Qg) (nC)	12.9 @ 4.5V	50 @ 4.5V	73 @ 10V	63 @ 10V	49 @ 4.5V	44 @ 4.5V
Input Capacitance (Ciss) (pF)	1570 @ 25V	4500 @ 20V	3845 @ 15V	2659 @ 20V	4766 @ 20V	3430 @ 20V
Power Dissipation (Max) (W)	3 (Tc)	2.5 (Ta)	2.5 (Ta)	2.5 (Ta)	2.5 (Ta)	2.5 (Ta)
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 150	-55 to 175	-55 to 175	-55 to 150
Package	8-SOIC	8-SO	8-SOIC	8-SOIC	8-SOIC	8-SO
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS3 Compliant	Yes	Yes	Yes	Not specified	Yes	Not specified

Engineering Selection Recommendations

IRF7842TRPBF (Infineon Technologies)

The IRF7842TRPBF is an active product with superior drain current capability (18A) and the lowest on-resistance (5 mOhm @ 17A, 10V) among all substitutes. This device provides performance headroom above the original STS15N4LLF5 specification. RoHS3 compliance and active product status ensure long-term availability. Operating temperature range matches the original part (-55°C to 150°C). This substitute is suitable for applications requiring enhanced current handling and reduced conduction losses.

FDS8842NZ (onsemi)

The FDS8842NZ maintains near-equivalent drain current (14.9A) and on-resistance (7 mOhm @ 14.9A, 10V) to the original part. Active product status and RoHS3 compliance support procurement continuity. Operating temperature range extends to 175°C, providing additional thermal margin. This substitute offers the closest electrical performance match to the STS15N4LLF5.

FDS4470 (Fairchild Semiconductor)

The FDS4470 provides 40V Vdss rating with 12.5A continuous drain current. On-resistance of 9 mOhm @ 12.5A, 10V represents a modest increase from the original specification. Active product status supports availability. Operating temperature range extends to 175°C. This substitute is applicable where drain current requirements are slightly reduced.

FDS4672A (onsemi)

The FDS4672A operates at 40V Vdss with 11A continuous drain current. On-resistance of 13 mOhm @ 11A, 4.5V indicates higher conduction losses compared to the original part. Active product status and RoHS3 compliance are confirmed. This substitute is suitable for lower current applications or where gate drive voltage is limited to 4.5V.

IRF7470TRPBF (International Rectifier)

The IRF7470TRPBF provides 40V Vdss rating with 10A continuous drain current. On-resistance of 13 mOhm @ 10A, 10V represents increased conduction losses. Active product status supports procurement. Operating temperature range matches the original part. This substitute is applicable for applications with reduced current requirements.

Frequently Asked Questions (FAQ)

Q: Can the STS15N4LLF5 be directly replaced with any of these substitute parts?

A: Direct replacement depends on application current requirements. The IRF7842TRPBF and FDS8842NZ provide equal or superior current handling. FDS4470, FDS4672A, and IRF7470TRPBF have reduced current ratings and are suitable only if application current does not exceed their specifications.

Q: What is the significance of the different drain current ratings?

A: Drain current rating determines the maximum continuous current the device can conduct. The original STS15N4LLF5 is rated for 15A. Substitutes with lower ratings (10A to 12.5A) cannot be used in applications requiring the full 15A specification. Substitutes with higher ratings (18A) provide additional current margin.

Q: How do on-resistance differences affect circuit performance?

A: On-resistance (Rds On) directly impacts conduction losses and heat generation. Lower on-resistance reduces power dissipation and improves efficiency. The IRF7842TRPBF (5 mOhm) dissipates less heat than the original part (6.7 mOhm). Higher on-resistance values increase thermal load and may require additional heat management.

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

A: All substitutes use 8-SOIC or 8-SO surface mount packages with identical 0.154" (3.90mm) width. Pin configurations are compatible for direct PCB replacement without layout modifications.

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

A: Tc (case temperature) and Ta (ambient temperature) represent different measurement points. Tc measurements are taken at the device case, while Ta measurements are taken at ambient conditions. Both specifications indicate the device operates across the -55°C to 150°C range for the original part and most substitutes.

Q: Do all substitute parts meet RoHS3 compliance?

A: IRF7842TRPBF, FDS8842NZ, and FDS4672A are confirmed RoHS3 compliant. FDS4470 and IRF7470TRPBF compliance status is not specified in the provided data.

Q: How does gate charge affect circuit design?

A: Gate charge (Qg) determines the energy required to switch the device. Lower gate charge reduces switching losses and allows faster switching speeds. The original STS15N4LLF5 has 12.9 nC @ 4.5V, the lowest among all parts listed. Substitutes with higher gate charge may require gate driver adjustments.

Q: Can substitutes with extended temperature ranges (-55°C to 175°C) be used in place of the original part?

A: Yes. Extended temperature range capability is a superset of the original specification. FDS4470 and FDS4672A support 175°C maximum junction temperature, providing additional thermal margin for high-temperature applications.

Q: What is the impact of different input capacitance values?

A: Input capacitance (Ciss) affects gate charge requirements and switching speed. The original part has 1570 pF @ 25V, the lowest value. Substitutes with higher capacitance (2659 to 4766 pF) require more gate charge and may increase switching losses or require stronger gate drivers.

Q: Which substitute provides the best overall performance match?

A: The FDS8842NZ provides the closest electrical performance match with 14.9A drain current, 7 mOhm on-resistance, and operating temperature range of -55°C to 150°C. The IRF7842TRPBF offers superior performance with higher current capability and lower on-resistance for applications requiring enhanced specifications.

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