MMBF4091 Equivalent & Substitute Parts

Part Overview

The MMBF4091 is an N-Channel JFET transistor manufactured by onsemi, designed for surface mount applications in the SOT-23-3 package. This device features a 40 V breakdown voltage rating and 350 mW maximum power dissipation. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing design support and component sourcing.

Substiute Parts

MMBF4091

onsemiIn Stock: 4377MMBF4091 Datasheet

Current PartRFQ

2SK545-11D-TB-E

onsemiIn Stock: 7142SK545-11D-TB-E Datasheet

SimilarRFQ

2SK209-GR(TE85L,F)

Toshiba Semiconductor and StorageIn Stock: 22122SK209-GR(TE85L,F) Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the MMBF4091 is determined by the following critical parameters:

• N-Channel JFET topology
• Voltage rating compatibility (40 V minimum breakdown voltage)
• Drain current capability (Idss specifications)
• Cutoff voltage characteristics (VGS off)
• Surface mount packaging (SOT-23-3 / SC-59 / TO-236-3 compatible)
• Power dissipation requirements (350 mW or greater)
• Operating temperature range support

The two identified substitute parts meet these criteria with variations in drain current and power ratings that remain within acceptable operating parameters for applications designed for the MMBF4091.

Parameter Comparison

Engineering Selection Recommendations

2SK209-GR(TE85L,F) is the preferred substitute for new designs and ongoing production. This part is currently active in production status, ensuring long-term availability and supply chain stability. It carries ROHS3 compliance certification and meets all critical electrical parameters for MMBF4091 replacement. The 50 V breakdown voltage provides additional voltage margin over the original 40 V specification. Operating temperature support to 125°C (TJ) is suitable for most applications within the MMBF4091 design envelope.

2SK545-11D-TB-E is an alternative substitute where inventory constraints or specific application requirements necessitate its use. This part maintains the same 40 V breakdown voltage as the original MMBF4091 and shares identical package specifications. However, it is also obsolete and carries lower power dissipation (125 mW versus 350 mW), making it suitable only for applications with reduced power requirements. ROHS3 compliance is confirmed.

Both substitutes maintain N-Channel JFET topology, surface mount SOT-23-3 packaging, and MSL 1 moisture sensitivity rating, ensuring mechanical and thermal compatibility with existing PCB designs.

Frequently Asked Questions (FAQ)

Q: Can the 2SK209-GR(TE85L,F) directly replace the MMBF4091 in existing designs?

A: Yes. Both devices share identical package specifications (SOT-23-3), N-Channel JFET topology, and compatible electrical characteristics. The 2SK209-GR(TE85L,F) features a higher 50 V breakdown voltage, which provides additional design margin. Verify that the application does not depend on the specific Idss or VGS off characteristics of the MMBF4091, as these parameters differ between the devices.

Q: What are the key differences between the two substitute parts?

A: The 2SK209-GR(TE85L,F) is currently active in production, while the 2SK545-11D-TB-E is obsolete. The 2SK209-GR features higher drain current (14 mA) and power dissipation (150 mW) compared to the 2SK545-11D-TB-E (60 µA, 125 mW). For new designs, the 2SK209-GR(TE85L,F) is recommended due to its active status and superior electrical performance.

Q: Are there any package compatibility concerns?

A: No. All three devices use identical package specifications: TO-236-3, SC-59, SOT-23-3. Pin assignments and footprints are compatible, allowing direct PCB substitution without layout modifications.

Q: What compliance certifications apply to these substitute parts?

A: Both substitute parts are ROHS3 compliant and carry REACH Unaffected status. Moisture sensitivity level is MSL 1 (Unlimited) for all three devices, indicating no special moisture handling requirements during storage or assembly.

Q: Why is the MMBF4091 obsolete, and what is the long-term availability outlook for substitutes?

A: The MMBF4091 has reached end-of-life status. The 2SK209-GR(TE85L,F) is currently in active production, providing assured long-term availability. The 2SK545-11D-TB-E is also obsolete and should be considered only as a secondary option when the 2SK209-GR is unavailable.