IRL3705ZSTRL Equivalent & Substitute Parts

Part Overview

The IRL3705ZSTRL is an N-Channel MOSFET manufactured by Infineon Technologies, rated for 55V drain-to-source voltage and 75A continuous drain current in a D2PAK surface mount package. This device is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and procurement.

The IRL3705ZSTRL operates as a power switching element suitable for applications requiring moderate voltage and high current handling in a compact surface mount form factor. Due to its obsolete status, alternative parts with matching or superior electrical and mechanical characteristics are required to maintain design continuity and ensure component availability.

Substiute Parts

IRL3705ZSTRL

Infineon TechnologiesIn Stock: 1124IRL3705ZSTRL Datasheet

Current PartRFQ

IRL3705ZSTRLPBF

Infineon TechnologiesIn Stock: 20463IRL3705ZSTRLPBF Datasheet

DirectRFQ

STB85NF55LT4

STMicroelectronicsIn Stock: 2222STB85NF55LT4 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the IRL3705ZSTRL is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

• FET Type: N-Channel
• Drain to Source Voltage (Vdss): 55 V
• Mounting Type: Surface Mount
• Package / Case: TO-263-3, D2PAK (2 Leads + Tab)

Performance Parameters for Compatibility:

• Current - Continuous Drain (Id) @ 25°C: 75 A or greater
• Rds On (Max) @ Id, Vgs: 8 mOhm or lower
• Vgs(th) (Max) @ Id: 3 V or lower
• Gate Charge (Qg) (Max) @ Vgs: 60 nC or lower
• Input Capacitance (Ciss) (Max) @ Vds: 2880 pF or lower

The identified substitute parts meet or exceed these parameters while maintaining identical package geometry and electrical interface requirements.

Parameter Comparison

Engineering Selection Recommendations

IRL3705ZSTRLPBF (Infineon Technologies)

The IRL3705ZSTRLPBF is a direct functional equivalent to the IRL3705ZSTRL with identical electrical specifications. This part is classified as active and carries ROHS3 compliance certification, addressing regulatory requirements that the original obsolete part does not meet. The IRL3705ZSTRLPBF maintains the same D2PAK package geometry and electrical performance envelope, enabling direct substitution in existing designs without circuit modification.

STB85NF55LT4 (STMicroelectronics)

The STB85NF55LT4 is a cross-manufacturer substitute that meets or exceeds the electrical requirements of the IRL3705ZSTRL. This device provides 80A continuous drain current compared to 75A, delivering enhanced current capacity. The STB85NF55LT4 is active and ROHS3 compliant. The part exhibits lower gate threshold voltage (2.5V versus 3V) and higher gate charge (110 nC versus 60 nC) and input capacitance (4050 pF versus 2880 pF). These parameter differences require circuit-level evaluation to confirm compatibility with gate drive circuitry and switching frequency requirements.

Both substitute parts are available in active production status with modern compliance certifications, providing long-term supply security compared to the obsolete original part.

Frequently Asked Questions (FAQ)

Q: Can the IRL3705ZSTRLPBF be used as a direct replacement for the IRL3705ZSTRL?

A: Yes. The IRL3705ZSTRLPBF is electrically and mechanically identical to the IRL3705ZSTRL. Both parts share the same drain-source voltage rating (55V), continuous drain current (75A), on-state resistance (8 mOhm), gate threshold voltage (3V), gate charge (60 nC), and input capacitance (2880 pF). The D2PAK package geometry is identical. The primary difference is product status and compliance: the IRL3705ZSTRLPBF is active and ROHS3 compliant, while the original is obsolete and non-compliant.

Q: What are the key differences between the IRL3705ZSTRLPBF and STB85NF55LT4?

A: Both parts operate at 55V and are housed in D2PAK packages. The STB85NF55LT4 provides higher continuous drain current (80A versus 75A) and lower gate threshold voltage (2.5V versus 3V). However, the STB85NF55LT4 exhibits higher gate charge (110 nC versus 60 nC) and input capacitance (4050 pF versus 2880 pF). These differences affect gate drive requirements and switching speed. The STB85NF55LT4 is manufactured by STMicroelectronics under the STripFET™ II series, while the IRL3705ZSTRLPBF is an Infineon HEXFET® device.

Q: Is the STB85NF55LT4 suitable for applications originally designed for the IRL3705ZSTRL?

A: The STB85NF55LT4 meets the voltage and current requirements of the IRL3705ZSTRL and is housed in the same D2PAK package. However, the higher gate charge and input capacitance require evaluation of gate drive circuit performance. Applications with tight switching frequency constraints or limited gate drive current may require circuit modification. The lower gate threshold voltage (2.5V) may also affect gate drive voltage selection.

Q: Are both substitute parts RoHS compliant?

A: Yes. Both the IRL3705ZSTRLPBF and STB85NF55LT4 are ROHS3 compliant. The original IRL3705ZSTRL is RoHS non-compliant. For applications subject to RoHS regulations, either substitute part is acceptable.

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

A: The IRL3705ZSTRLPBF can be used interchangeably with the IRL3705ZSTRL without circuit modification. The STB85NF55LT4 requires evaluation of gate drive circuit compatibility due to differences in gate charge and input capacitance. Pin-to-pin compatibility is confirmed for all three parts in the D2PAK package.

Q: What is the inventory status of these substitute parts?

A: The IRL3705ZSTRLPBF has 20,371 pieces in stock. The STB85NF55LT4 has 2,146 pieces in stock. The original IRL3705ZSTRL has 1,100 pieces in stock but is classified as obsolete.