MMBF4092 Equivalent & Substitute Parts

Part Overview

The MMBF4092 is an N-Channel JFET transistor manufactured by onsemi, designed for surface mount applications in the SOT-23-3 package. This device operates at 40 V breakdown voltage with a maximum drain current of 15 mA and 350 mW power dissipation. The part is currently listed as obsolete, making equivalent and substitute parts necessary for ongoing design support and component sourcing.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Voltage - Breakdown (V(BR)GSS)	40	V
Current - Drain (Idss) @ Vds (Vgs=0)	15 mA @ 20 V	mA
Voltage - Cutoff (VGS off) @ Id	2 V @ 1 nA	V
Input Capacitance (Ciss) (Max) @ Vds	16 pF @ 20 V	pF
Resistance - RDS(On)	50	Ohms
Power - Max	350	mW
Operating Temperature	-55 to 150	°C (TJ)
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—

Substitute Part Grouping Explanation

Substitution for the MMBF4092 is determined by the following critical parameters:

N-Channel JFET topology
Voltage rating: 40 V minimum breakdown voltage (V(BR)GSS)
Power dissipation: 350 mW maximum
Surface mount packaging: SOT-23-3 / SC-59 / TO-236-3 compatible
Operating temperature range: -55°C to 150°C

The substitute parts listed below meet these core electrical and mechanical requirements. Variations in drain current (Idss), cutoff voltage (VGS off), and input capacitance are within acceptable ranges for N-Channel JFET applications where the primary function is signal switching or amplification in low-current circuits.

Parameter Comparison

Parameter	MMBF4092	2SK545-11D-TB-E	MMBF5103	2SK209-GR(TE85L,F)
Manufacturer	onsemi	onsemi	onsemi	Toshiba Semiconductor and Storage
FET Type	N-Channel	N-Channel	N-Channel	N-Channel
Voltage - Breakdown (V(BR)GSS)	40 V	40 V	40 V	50 V
Current - Drain (Idss) @ Vds (Vgs=0)	15 mA @ 20 V	60 µA @ 10 V	10 mA @ 15 V	14 mA @ 10 V
Voltage - Cutoff (VGS off) @ Id	2 V @ 1 nA	1.5 V @ 1 µA	1.2 V @ 1 nA	1.5 V @ 100 nA
Input Capacitance (Ciss) (Max) @ Vds	16 pF @ 20 V	1.7 pF @ 10 V	16 pF @ 15 V	13 pF @ 10 V
Power - Max	350 mW	125 mW	350 mW	150 mW
Operating Temperature	-55 to 150°C	Not specified	-55 to 150°C	125°C (TJ)
Package / Case	SOT-23-3	SMCP	SOT-23-3	SC-59
Product Status	Obsolete	Obsolete	Active	Active
RoHS Status	REACH Unaffected	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For new designs and ongoing production, MMBF5103 is the primary recommended substitute. This part maintains identical electrical specifications (40 V breakdown, 350 mW power, -55°C to 150°C operating range) and package compatibility (SOT-23-3), while offering active product status and ROHS3 compliance. Existing inventory of MMBF4092 can be used interchangeably with MMBF5103 without circuit modification.

The 2SK209-GR(TE85L,F) from Toshiba Semiconductor and Storage is an alternative substitute with higher voltage rating (50 V) and comparable drain current characteristics. This part is actively manufactured and ROHS3 compliant, suitable for applications where the additional voltage margin is beneficial.

The 2SK545-11D-TB-E is not recommended for new designs due to obsolete status and significantly reduced power rating (125 mW versus 350 mW), despite meeting the 40 V voltage requirement.

Frequently Asked Questions (FAQ)

Q: Can MMBF5103 directly replace MMBF4092 in existing circuits?

A: Yes. Both parts share identical voltage ratings (40 V), power dissipation (350 mW), operating temperature range (-55°C to 150°C), and SOT-23-3 packaging. Electrical characteristics are compatible for N-Channel JFET applications.

Q: What is the difference between SOT-23-3, SC-59, and SMCP packages?

A: SOT-23-3, SC-59, and SMCP are equivalent surface mount packages for three-terminal devices. All substitute parts listed use compatible package designations suitable for the same PCB footprint.

Q: Why is 2SK209-GR(TE85L,F) rated at 50 V instead of 40 V?

A: The 2SK209-GR(TE85L,F) has a higher voltage breakdown rating (50 V) compared to the MMBF4092 (40 V). This provides additional voltage margin and is acceptable for substitution in applications designed for 40 V operation.

Q: Is MMBF5103 suitable for new production designs?

A: Yes. MMBF5103 is actively manufactured, ROHS3 compliant, and electrically equivalent to MMBF4092. It is the recommended choice for new designs requiring N-Channel JFET functionality in the SOT-23-3 package.

Q: What compliance certifications apply to these substitute parts?

A: MMBF5103 and 2SK209-GR(TE85L,F) are both ROHS3 compliant and REACH unaffected. All parts carry EAR99 ECCN classification and HTSUS code 8541.21.0095.

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