AUIRFZ44NS N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The AUIRFZ44NS is an N-Channel MOSFET manufactured by Infineon Technologies, part of the HEXFET® series. This device is rated for 55V drain-to-source voltage with 49A continuous drain current in a surface mount D2PAK package. The product status is listed as Obsolete, making identification of equivalent and substitute parts essential for ongoing design support, maintenance, and production continuity. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges for this MOSFET category.

Substiute Parts

AUIRFZ44NS

Infineon TechnologiesIn Stock: 3761AUIRFZ44NS Datasheet

Current PartRFQ

STB55NF06LT4

STMicroelectronicsIn Stock: 1382STB55NF06LT4 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the AUIRFZ44NS is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Drain-to-Source Voltage (Vdss) must be equal to or greater than 55V
• Continuous Drain Current (Id) must be equal to or greater than 49A
• Package type must be D2PAK (TO-263-3) for mechanical compatibility
• FET Type must be N-Channel MOSFET
• Operating temperature range must encompass -55°C to 175°C
• RoHS3 compliance and MSL Level 1 rating required

Secondary Compatibility Parameters:

• Rds On (Max) should not significantly exceed the original specification to maintain thermal performance
• Gate Charge (Qg) and Input Capacitance (Ciss) affect switching characteristics
• Gate Threshold Voltage (Vgs(th)) and maximum gate voltage (Vgs Max) must be compatible with existing drive circuitry

The STB55NF06LT4 from STMicroelectronics meets all primary substitution criteria and is classified as an equivalent substitute for the obsolete AUIRFZ44NS.

Parameter Comparison

Engineering Selection Recommendations

For Direct Substitution:

The STB55NF06LT4 is qualified as a direct substitute for the obsolete AUIRFZ44NS based on the following factors:

1. Product Status Alignment: The STB55NF06LT4 carries Active product status, ensuring continued availability and manufacturing support, whereas the AUIRFZ44NS is Obsolete.

2. Electrical Parameter Compatibility: The STB55NF06LT4 exceeds the minimum electrical requirements of the AUIRFZ44NS across all critical parameters (Vdss: 60V vs. 55V; Id: 55A vs. 49A). Rds On performance is comparable, and power dissipation is equivalent.

3. Mechanical Compatibility: Both devices use identical D2PAK (TO-263-3) surface mount packaging, ensuring PCB layout and thermal management compatibility without redesign.

4. Compliance Certification: Both parts maintain ROHS3 compliance, REACH Unaffected status, and MSL Level 1 rating, meeting regulatory and environmental requirements.

5. Temperature Operating Range: Identical operating temperature specifications (-55°C to 175°C) ensure thermal performance equivalence in all application environments.

Design Considerations:

The STB55NF06LT4 features lower gate charge (37 nC vs. 63 nC) and operates with a slightly higher gate threshold voltage (4.7V vs. 4V). These characteristics may result in faster switching response and reduced gate drive power consumption. The maximum gate voltage rating is 16V (versus 20V for the AUIRFZ44NS), which is compatible with standard 10V and 5V gate drive circuits specified in the STB55NF06LT4 datasheet.

Frequently Asked Questions (FAQ)

Q1: Can the STB55NF06LT4 be used as a direct replacement for the AUIRFZ44NS without circuit modifications?

A: Yes. The STB55NF06LT4 is mechanically and electrically compatible with the AUIRFZ44NS. Both devices share identical D2PAK packaging and operating temperature ranges. The STB55NF06LT4 provides equal or superior electrical performance across all critical parameters. No PCB layout changes are required.

Q2: What is the significance of the higher Vdss rating (60V) on the STB55NF06LT4 compared to the AUIRFZ44NS (55V)?

A: The higher Vdss rating provides additional voltage margin and enhanced reliability in applications operating near the 55V specification limit. This does not negatively impact performance in circuits designed for 55V operation; it only increases the device's voltage handling capability.

Q3: How do the gate charge differences affect circuit performance?

A: The STB55NF06LT4 has lower gate charge (37 nC vs. 63 nC), which reduces the energy required to switch the device and may decrease gate drive power consumption. This typically results in faster switching transitions and improved efficiency. Existing gate drive circuits designed for the AUIRFZ44NS will operate correctly with the STB55NF06LT4.

Q4: Are there any restrictions on the maximum gate voltage when using the STB55NF06LT4?

A: The STB55NF06LT4 has a maximum gate voltage rating of ±16V, compared to ±20V for the AUIRFZ44NS. Standard gate drive circuits operating at 10V or 5V are fully compatible. Applications requiring gate voltages exceeding ±16V must be evaluated against the STB55NF06LT4 datasheet specifications.

Q5: Do both parts meet the same regulatory and environmental compliance standards?

A: Yes. Both the AUIRFZ44NS and STB55NF06LT4 are ROHS3 compliant, REACH Unaffected, and carry MSL Level 1 (Unlimited) moisture sensitivity ratings. They meet identical regulatory requirements for industrial and commercial applications.

Q6: What is the impact of the slightly higher gate threshold voltage (4.7V vs. 4V) on circuit design?

A: The gate threshold voltage difference is within the normal operating range for N-Channel MOSFETs and does not require circuit redesign. Standard gate drive circuits providing 10V or 5V gate drive will fully enhance both devices. The STB55NF06LT4 may require marginally higher gate voltage to achieve identical on-state resistance, but this is negligible in practical applications.

Q7: Is the STB55NF06LT4 available in the same packaging options as the AUIRFZ44NS?

A: Both devices are supplied in D2PAK (TO-263-3) surface mount packaging. The STB55NF06LT4 is available in Cut Tape (CT) and Digi-Reel® packaging formats, ensuring compatibility with standard component handling and assembly processes.