BUL44 Equivalent & Substitute Parts

Part Overview

The BUL44 is an NPN bipolar junction transistor manufactured by onsemi, designed for switchmode applications in a TO-220 through-hole package. This component operates at 400 V collector-emitter breakdown voltage with a maximum collector current of 2 A and 50 W power dissipation capability. The BUL44 is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing design requirements and production continuity.

Substiute Parts

BUL44

onsemiIn Stock: 4970BUL44 Datasheet

Current PartRFQ

TSC741CZ C0G

Taiwan Semiconductor CorporationIn Stock: 1166TSC741CZ C0G Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the obsolete BUL44 is determined by electrical and mechanical compatibility within the following parameter constraints:

Electrical Compatibility Criteria:

• Transistor type must be NPN
• Collector-emitter breakdown voltage must equal or exceed 400 V
• Maximum collector current must equal or exceed 2 A
• Maximum power dissipation must equal or exceed 50 W
• Operating temperature range must encompass the BUL44 specification

Mechanical Compatibility Criteria:

• Package type must be TO-220-3
• Mounting configuration must be through-hole

The TSC741CZ C0G meets these substitution criteria with enhanced electrical ratings (450 V breakdown, 2.5 A collector current, 60 W power) and maintains identical mechanical packaging.

Parameter Comparison

Engineering Selection Recommendations

The TSC741CZ C0G is a direct substitute for the BUL44 in applications requiring NPN switchmode transistor functionality. The substitute part provides superior electrical performance with higher voltage and current ratings while maintaining identical TO-220-3 package geometry and through-hole mounting configuration.

Compliance Considerations:

The TSC741CZ C0G holds ROHS3 compliance status, whereas the BUL44 is RoHS non-compliant. Both components are REACH Unaffected and classified under ECCN EAR99. For applications subject to RoHS regulatory requirements, the TSC741CZ C0G satisfies compliance obligations while the BUL44 does not.

Availability and Supply Chain:

The BUL44 is obsolete with existing inventory of 4954 pieces. The TSC741CZ C0G is active production with 1128 pieces in stock, ensuring long-term supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can the TSC741CZ C0G directly replace the BUL44 in existing circuit designs?

A: Yes. The TSC741CZ C0G meets all minimum electrical requirements (400 V breakdown, 2 A collector current, 50 W power) and shares identical TO-220-3 package geometry. Pin configuration and mounting footprint are compatible.

Q: What are the key electrical differences between these parts?

A: The TSC741CZ C0G provides higher voltage rating (450 V vs. 400 V), higher collector current capability (2.5 A vs. 2 A), and greater power dissipation (60 W vs. 50 W). These enhancements provide design margin without requiring circuit modification.

Q: Are there thermal management differences between the BUL44 and TSC741CZ C0G?

A: Both components operate to a maximum junction temperature of 150°C. The TSC741CZ C0G supports higher power dissipation (60 W), which may reduce thermal stress in applications operating near the BUL44 power limit.

Q: Does the TSC741CZ C0G meet regulatory compliance requirements?

A: The TSC741CZ C0G is ROHS3 compliant. The BUL44 is RoHS non-compliant. For applications subject to RoHS directives, the TSC741CZ C0G is the appropriate selection.

Q: What is the moisture sensitivity level difference?

A: The BUL44 has MSL 1 (Unlimited), while the TSC741CZ C0G has MSL 3 (168 Hours). The TSC741CZ C0G requires controlled moisture exposure during storage and handling per IPC-A-610 standards.

Q: Are there frequency response considerations for high-speed switching applications?

A: The BUL44 specifies 13 MHz transition frequency. The TSC741CZ C0G does not provide transition frequency specification in available documentation. For applications requiring confirmed frequency response, the BUL44 specification should be compared against actual TSC741CZ C0G performance data from the manufacturer.