SD1728 RF Transistor NPN 55V Equivalent & Substitute Parts

Part Overview

The SD1728 is an RF Transistor NPN rated at 55V maximum collector-emitter breakdown voltage, designed for high-power RF applications with a maximum power dissipation of 330W. This component is classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing design requirements and production continuity. The part is manufactured by STMicroelectronics and supplied in M177 surface mount packaging.

Substiute Parts

SD1728

STMicroelectronicsIn Stock: 1009SD1728 Datasheet

Current PartRFQ

SD2933W

STMicroelectronicsIn Stock: 6800SD2933W Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the SD1728 is based on the following critical parameters that determine functional equivalence:

Package Compatibility: Both the main part and substitute must utilize the M177 surface mount package to ensure mechanical and thermal compatibility with existing PCB layouts.

Voltage Rating: The substitute must maintain a voltage rating sufficient for the application. The SD1728 specifies 55V maximum collector-emitter breakdown voltage.

Power Dissipation: The substitute must support the thermal requirements of the application, with the SD1728 rated at 330W maximum power dissipation.

Current Handling: The SD1728 is rated for 40A maximum collector current, establishing the current capacity requirement for substitutes.

Manufacturer Continuity: STMicroelectronics supplies both the original part and identified substitutes, ensuring consistent quality and availability.

Compliance Standards: Both parts maintain ROHS3 compliance and REACH unaffected status, meeting regulatory requirements.

The SD2933W is identified as a substitute part based on shared M177 packaging, STMicroelectronics manufacture, and comparable power handling characteristics, though it represents a different semiconductor technology (MOSFET versus BJT).

Parameter Comparison

Engineering Selection Recommendations

The SD2933W serves as an active substitute for the obsolete SD1728, offering continued availability through STMicroelectronics. Both components share identical M177 surface mount packaging, enabling direct PCB layout compatibility without redesign.

The SD2933W maintains comparable current handling at 40A and power dissipation at 300W, which approaches the SD1728 specification of 330W. The voltage rating of the SD2933W at 50V test voltage is marginally lower than the SD1728 at 55V; however, the rated voltage specification of 125V for the SD2933W provides operational headroom for most RF applications.

Both parts maintain ROHS3 compliance and REACH unaffected status, satisfying regulatory requirements for new production. The SD2933W is currently in active production status, ensuring long-term supply availability compared to the obsolete SD1728.

The primary technical distinction is the semiconductor technology: the SD1728 is a bipolar junction transistor (BJT), while the SD2933W is a metal-oxide-semiconductor field-effect transistor (MOSFET). This difference affects circuit behavior, biasing requirements, and impedance characteristics. Circuit validation is required to confirm functional equivalence within the specific application context.

Frequently Asked Questions (FAQ)

Q: Can the SD2933W be used as a direct replacement for the SD1728 without PCB modifications?

A: Both parts utilize the M177 surface mount package, enabling mechanical compatibility without PCB layout changes. However, the transition from BJT to MOSFET technology requires circuit-level evaluation to confirm functional equivalence, including biasing network adjustments and impedance matching considerations.

Q: What is the voltage rating difference between these parts?

A: The SD1728 specifies 55V maximum collector-emitter breakdown voltage. The SD2933W specifies 50V test voltage and 125V rated voltage. The 50V test voltage is 5V lower than the SD1728 specification, while the 125V rated voltage provides additional operational margin. Application voltage requirements determine suitability.

Q: Are both parts compliant with current regulatory standards?

A: Both the SD1728 and SD2933W are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements for electronic component manufacturing and use.

Q: What is the power dissipation difference?

A: The SD1728 is rated at 330W maximum power dissipation, while the SD2933W is rated at 300W. The 30W difference represents approximately 9% lower power handling in the substitute. Thermal design validation is required for applications operating near maximum power specifications.

Q: Why is the SD1728 listed as obsolete?

A: The SD1728 is classified as obsolete by STMicroelectronics, indicating discontinued production and limited availability. The SD2933W, maintained in active production status, provides continued access to equivalent RF semiconductor functionality.

Q: How do the gain specifications compare?

A: The SD1728 specifies 15dB to 17dB gain, while the SD2933W specifies 23.5dB gain. The higher gain of the SD2933W reflects the different amplification characteristics of MOSFET versus BJT technology and may require circuit compensation in existing designs.

Q: Is the M177 package suitable for high-frequency RF applications?

A: The M177 package is specified for both the SD1728 and SD2933W in RF applications, including frequency operation at 30MHz for the SD2933W. Package suitability depends on specific application frequency requirements and thermal management implementation.