BUT70W Equivalent & Substitute Parts

Part Overview

The BUT70W is an NPN bipolar junction transistor manufactured by STMicroelectronics, rated for 125 V collector-emitter breakdown voltage and 32 A maximum collector current in a TO-247-3 through-hole package. This device is classified as obsolete, making identification of suitable substitute components necessary for ongoing design support and production continuity. The 200 W power rating and saturation characteristics position this transistor for high-current switching applications requiring robust thermal management.

Substiute Parts

BUT70W

STMicroelectronicsIn Stock: 703BUT70W Datasheet

Current PartRFQ

BUTW92

STMicroelectronicsIn Stock: 9125BUTW92 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BUT70W is determined by compatibility across the following critical parameters:

Package and Mounting Compatibility: Both the main part and substitute must use the TO-247-3 through-hole package to ensure mechanical fit and thermal interface compatibility with existing PCB layouts and heatsink assemblies.

Transistor Type: The substitute must be an NPN bipolar junction transistor to maintain circuit polarity and biasing requirements.

Electrical Performance Envelope: The substitute must satisfy the application's voltage and current demands. A substitute with higher voltage and current ratings provides design margin and extended operational capability. The BUTW92 offers 250 V breakdown voltage and 45 A collector current, exceeding the BUT70W specifications.

Thermal Characteristics: Operating temperature rating of 150°C (TJ) is maintained across both devices, ensuring thermal performance consistency.

Regulatory Compliance: Both devices carry ROHS3 compliance and REACH unaffected status, meeting modern environmental and safety standards.

Parameter Comparison

Engineering Selection Recommendations

The BUTW92 serves as a direct substitute for the obsolete BUT70W in applications requiring NPN high-current switching in the TO-247-3 package. The BUTW92 maintains active product status with STMicroelectronics, ensuring long-term availability and supply chain stability. Both devices comply with ROHS3 and REACH requirements, supporting modern manufacturing and environmental standards.

The BUTW92 provides enhanced electrical performance with 250 V breakdown voltage and 45 A collector current capability, compared to the BUT70W's 125 V and 32 A ratings. This performance margin accommodates applications with higher voltage transients or increased current demands. The maximum power rating of the BUTW92 is 180 W, slightly lower than the BUT70W's 200 W specification; circuit thermal design must account for this difference in high-power dissipation scenarios.

Both devices share identical TO-247-3 packaging and 150°C maximum junction temperature, enabling direct mechanical and thermal interface compatibility with existing designs. The BUTW92's higher saturation voltage (1 V versus 900 mV at specified test conditions) represents a minor trade-off in switching efficiency that is typically negligible in most switching applications.

Frequently Asked Questions (FAQ)

Q: Can the BUTW92 replace the BUT70W in existing circuit designs?

A: Yes. Both transistors are NPN devices in TO-247-3 packages with identical mounting and thermal characteristics. The BUTW92 provides higher voltage and current ratings, making it suitable for applications originally designed for the BUT70W. Circuit validation is required to confirm performance in specific applications.

Q: What is the primary reason for substituting the BUT70W?

A: The BUT70W is classified as obsolete. The BUTW92 is an active product from the same manufacturer, ensuring continued availability and supply chain support.

Q: Are there package compatibility concerns when substituting the BUTW92 for the BUT70W?

A: No. Both devices use the TO-247-3 through-hole package with identical pinout and mechanical dimensions, allowing direct PCB and heatsink interface compatibility.

Q: How do the electrical ratings compare?

A: The BUTW92 exceeds the BUT70W in voltage (250 V versus 125 V) and current (45 A versus 32 A) ratings. The BUT70W has a slightly higher maximum power rating (200 W versus 180 W). Applications operating within the BUT70W's original specifications will function within the BUTW92's operational envelope.

Q: Do both devices meet current environmental compliance standards?

A: Yes. Both the BUT70W and BUTW92 are ROHS3 compliant and REACH unaffected, meeting modern environmental and regulatory requirements.

Q: What is the difference in saturation voltage between these devices?

A: The BUT70W saturates at 900 mV (at 7A, 70A test conditions), while the BUTW92 saturates at 1 V (at 15A, 60A test conditions). This difference has minimal impact on most switching applications but should be evaluated in designs with tight efficiency margins.