FMB3946 Equivalent & Substitute Parts

Part Overview

The FMB3946 is an active-status bipolar junction transistor (BJT) array manufactured by onsemi, featuring complementary NPN and PNP transistors in a SuperSOT™-6 surface mount package. This device is designed for general-purpose switching and amplification applications with a maximum collector current of 200mA and collector-emitter breakdown voltage of 40V. The part is RoHS3 compliant with unlimited moisture sensitivity level (MSL 1) and is currently in production with substantial inventory availability. Equivalent and substitute parts are identified for applications requiring alternative packaging formats, enhanced current ratings, or automotive-grade qualifications.

Substiute Parts

FMB3946

onsemiIn Stock: 42184FMB3946 Datasheet

Current PartRFQ

BC817DPN,115

Nexperia USA Inc.In Stock: 2532BC817DPN,115 Datasheet

SimilarRFQ

PBSS4240DPN,115

Nexperia USA Inc.In Stock: 10524PBSS4240DPN,115 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the FMB3946 are qualified based on the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Transistor type configuration (NPN, PNP complementary pair)
• Collector-emitter breakdown voltage rating (40V minimum)
• Surface mount package format (6-pin TSOP/SOT-457 compatible footprints)
• Operating temperature range (-55°C to 150°C or higher)
• RoHS3 compliance and MSL 1 rating

Allowable Parameter Variations:

• Collector current (Ic) may exceed 200mA
• Power dissipation may exceed 700mW
• Transition frequency may differ from 200MHz
• Vce saturation characteristics may vary within device specifications
• DC current gain (hFE) may exceed minimum 100 specification

The identified substitutes (BC817DPN,115 and PBSS4240DPN,115) maintain electrical compatibility within the specified voltage and temperature operating ranges while offering enhanced current-handling capability and automotive-grade qualifications in certain variants.

Parameter Comparison

Engineering Selection Recommendations

FMB3946 (Primary Selection): The FMB3946 remains the optimal choice for applications requiring the specified SuperSOT™-6 package format with 200mA collector current capability and 200MHz transition frequency. This part is active in production with high inventory availability and meets all RoHS3 and REACH compliance requirements.

BC817DPN,115 (Nexperia Alternative): The BC817DPN,115 provides a substitute option with enhanced collector current rating (500mA) and higher collector-emitter breakdown voltage (45V). This part carries AEC-Q101 automotive qualification, making it suitable for automotive applications. The 6-TSOP package format is mechanically compatible with SOT-457 footprints. Transition frequency is reduced to 100MHz/80MHz, which may impact high-frequency switching applications.

PBSS4240DPN,115 (Nexperia High-Current Alternative): The PBSS4240DPN,115 is specified for applications requiring significantly higher collector current (1.35A NPN, 1.1A PNP) while maintaining the 40V collector-emitter breakdown voltage rating. This part features AEC-Q100 automotive qualification and 1.1W power dissipation capability. The 6-TSOP package format is mechanically compatible with SOT-457 footprints. Transition frequency of 150MHz supports moderate-speed switching applications.

All substitute parts maintain RoHS3 compliance, MSL 1 rating, and active product status. Selection between substitutes depends on specific application requirements for collector current, transition frequency, and automotive qualification level.

Frequently Asked Questions (FAQ)

Q: Can BC817DPN,115 be used as a direct replacement for FMB3946?

A: BC817DPN,115 is electrically compatible within the 40V to 45V collector-emitter breakdown voltage range and maintains the complementary NPN/PNP transistor configuration. However, the 6-TSOP package differs from the SuperSOT™-6 package of the FMB3946. PCB layout modifications may be required to accommodate the different package footprint. The reduced transition frequency (100MHz/80MHz versus 200MHz) must be evaluated for timing-critical applications.

Q: What are the key differences between BC817DPN,115 and PBSS4240DPN,115?

A: The primary differences are collector current ratings (500mA versus 1.35A/1.1A), power dissipation (600mW versus 1.1W), transition frequency (100MHz/80MHz versus 150MHz), and automotive qualification level (AEC-Q101 versus AEC-Q100). Both parts use the 6-TSOP package format and maintain 40V to 45V collector-emitter breakdown voltage ratings.

Q: Are package footprints compatible between FMB3946 and the substitute parts?

A: The FMB3946 uses SuperSOT™-6 (SOT-23-6 Thin, TSOT-23-6) packaging, while BC817DPN,115 and PBSS4240DPN,115 use 6-TSOP (SC-74, SOT-457) packaging. These are distinct package formats with different pin configurations and footprints. PCB redesign is required for substitution.

Q: Do all parts meet automotive qualification requirements?

A: The FMB3946 is standard-grade without automotive qualification. BC817DPN,115 carries AEC-Q101 qualification, and PBSS4240DPN,115 carries AEC-Q100 qualification. For automotive applications, BC817DPN,115 or PBSS4240DPN,115 are the appropriate selections.

Q: What is the operating temperature range for each part?

A: FMB3946 operates from -55°C to 150°C (TJ). BC817DPN,115 and PBSS4240DPN,115 both specify 150°C maximum junction temperature. The FMB3946 provides extended low-temperature operation to -55°C, which may be required for certain industrial or aerospace applications.

Q: How do transition frequencies compare across these parts?

A: FMB3946 features 200MHz transition frequency, PBSS4240DPN,115 features 150MHz, and BC817DPN,115 features 100MHz/80MHz. Applications requiring switching speeds above 150MHz should retain the FMB3946 or evaluate PBSS4240DPN,115 as the minimum acceptable substitute.

Q: Are all parts RoHS3 compliant?

A: Yes. FMB3946, BC817DPN,115, and PBSS4240DPN,115 are all RoHS3 compliant with MSL 1 (unlimited) moisture sensitivity level and REACH unaffected status.