STD55NH2LLT4 Equivalent & Substitute Parts

Part Overview

The STD55NH2LLT4 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 24V drain-to-source voltage with 40A continuous drain current at 25°C. This device is housed in a DPAK (TO-252-3) surface mount package and is designed for general-purpose switching applications requiring moderate voltage and current handling.

The STD55NH2LLT4 carries an Obsolete product status, indicating that STMicroelectronics has discontinued this component. Identifying equivalent and substitute parts is necessary to maintain design continuity, support existing production requirements, and ensure long-term component availability for legacy systems and new designs requiring similar electrical performance.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	24	V
Continuous Drain Current (Id) @ 25°C	40	A (Tc)
On-State Resistance (Rds On Max) @ 20A, 10V	11	mOhm
Gate Threshold Voltage (Vgs(th) Max) @ 250µA	1	V
Gate Charge (Qg Max) @ 4.5V	11	nC
Power Dissipation (Max)	60	W (Tc)
Operating Temperature Range	-55 to 175	°C (TJ)
Package Type	DPAK (TO-252-3)	Surface Mount
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the STD55NH2LLT4 is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Drain-to-Source Voltage (Vdss) must equal or exceed 24V
Continuous Drain Current (Id) must equal or exceed 40A at 25°C
On-State Resistance (Rds On) must not significantly exceed 11mOhm to maintain thermal performance
Gate Threshold Voltage (Vgs(th)) must be compatible with existing drive circuitry
Operating temperature range must encompass -55°C to 175°C

Mechanical Compatibility Criteria:

Package type must be DPAK (TO-252-3) surface mount
Pin configuration must be identical (2 Leads + Tab)
Mounting footprint must be compatible with existing PCB layouts

Regulatory Compliance:

RoHS3 compliance required
REACH Unaffected status required

The IRLR8259TRPBF meets these substitution criteria with electrical ratings that exceed the STD55NH2LLT4 specifications while maintaining identical package geometry and regulatory compliance.

Parameter Comparison

Parameter	STD55NH2LLT4 (Main Part)	IRLR8259TRPBF (Substitute)	Unit
Manufacturer	STMicroelectronics	Infineon Technologies	—
FET Type	N-Channel	N-Channel	—
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	—
Drain-to-Source Voltage (Vdss)	24	25	V
Continuous Drain Current (Id) @ 25°C	40	57	A (Tc)
On-State Resistance (Rds On Max)	11 @ 20A, 10V	8.7 @ 21A, 10V	mOhm
Gate Threshold Voltage (Vgs(th) Max)	1 @ 250µA	2.35 @ 25µA	V
Gate Charge (Qg Max) @ 4.5V	11	10	nC
Maximum Gate Voltage (Vgs Max)	±16	±20	V
Input Capacitance (Ciss Max)	990 @ 25V	900 @ 13V	pF
Power Dissipation (Max)	60	48	W (Tc)
Operating Temperature Range	-55 to 175	-55 to 175	°C (TJ)
Mounting Type	Surface Mount	Surface Mount	—
Package Type	DPAK (TO-252-3)	TO-252AA (DPAK)	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	—
Product Status	Obsolete	Not For New Designs	—

Engineering Selection Recommendations

IRLR8259TRPBF as Primary Substitute:

The IRLR8259TRPBF is a direct electrical and mechanical substitute for the STD55NH2LLT4. This Infineon Technologies device provides superior electrical performance across all critical parameters:

Vdss rating of 25V exceeds the 24V requirement, providing additional voltage margin
Continuous drain current of 57A exceeds the 40A specification, enabling higher current capacity
On-state resistance of 8.7mOhm is lower than the 11mOhm maximum, resulting in reduced conduction losses and improved thermal efficiency
Gate charge of 10nC is comparable to the 11nC specification, maintaining similar switching characteristics
Identical DPAK (TO-252-3) package geometry ensures direct PCB footprint compatibility

Both devices maintain identical operating temperature ranges (-55°C to 175°C), RoHS3 compliance, and REACH Unaffected status. The IRLR8259TRPBF is available in Tape & Reel packaging with 46,209 pieces in stock, providing immediate availability for production requirements.

The IRLR8259TRPBF carries a "Not For New Designs" product status, indicating that while the device remains available, Infineon may have newer alternatives for future development. For legacy system support and existing production continuity, this substitute is suitable.

Frequently Asked Questions (FAQ)

Q: Can the IRLR8259TRPBF directly replace the STD55NH2LLT4 without circuit modifications?

A: Yes. The IRLR8259TRPBF is electrically and mechanically compatible with the STD55NH2LLT4. Both devices are N-Channel MOSFETs in identical DPAK (TO-252-3) packages with compatible pin configurations. The substitute device exceeds all electrical specifications of the original part, including voltage rating, current capacity, and on-state resistance. No circuit modifications are required for direct substitution.

Q: What are the key electrical advantages of the IRLR8259TRPBF over the STD55NH2LLT4?

A: The IRLR8259TRPBF provides three primary electrical advantages: (1) higher continuous drain current rating of 57A versus 40A, enabling operation at higher current levels; (2) lower on-state resistance of 8.7mOhm versus 11mOhm, reducing conduction losses and heat generation; (3) higher drain-to-source voltage rating of 25V versus 24V, providing additional voltage margin. These improvements result in better thermal performance and greater design headroom.

Q: Are there any thermal performance differences between these devices?

A: The IRLR8259TRPBF has a maximum power dissipation rating of 48W compared to the STD55NH2LLT4 at 60W. However, the lower on-state resistance of the IRLR8259TRPBF (8.7mOhm versus 11mOhm) results in reduced conduction losses during operation. In most applications, the IRLR8259TRPBF will generate less heat than the original part due to its superior on-state resistance characteristics.

Q: Are both devices RoHS3 compliant?

A: Yes. Both the STD55NH2LLT4 and IRLR8259TRPBF are ROHS3 Compliant and REACH Unaffected, meeting current environmental and regulatory requirements for electronic components.

Q: What is the difference between the product status designations "Obsolete" and "Not For New Designs"?

A: "Obsolete" indicates that STMicroelectronics has discontinued the STD55NH2LLT4 and no longer manufactures or supports this device. "Not For New Designs" indicates that Infineon continues to manufacture the IRLR8259TRPBF for existing customer support but recommends newer alternatives for new product development. For legacy system maintenance and existing production support, the IRLR8259TRPBF remains a viable substitute.

Q: Are the gate charge characteristics compatible between these devices?

A: Yes. The gate charge specifications are nearly identical: STD55NH2LLT4 at 11nC versus IRLR8259TRPBF at 10nC (both measured at 4.5V). This similarity ensures compatible switching behavior and driver circuit performance. Existing gate drive circuitry designed for the STD55NH2LLT4 will operate effectively with the IRLR8259TRPBF.

Q: Can the IRLR8259TRPBF be used in applications requiring the full 40A continuous current specification?

A: Yes. The IRLR8259TRPBF is rated for 57A continuous drain current at 25°C, significantly exceeding the 40A requirement of the original STD55NH2LLT4. The substitute device is fully capable of supporting all current levels up to and beyond the original specification.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message