MMBF5459 Equivalent & Substitute Parts

Part Overview

The MMBF5459 is an N-Channel JFET transistor manufactured by onsemi, housed in a SOT-23-3 surface mount package. This device is rated for 25 V breakdown voltage with 350 mW maximum power dissipation and operates across the temperature range of -55°C to 150°C. The MMBF5459 is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts maintain the same package footprint and core electrical characteristics while offering active product status and continued availability.

Key Parameters

Parameter	Value	Unit
Voltage - Breakdown (V(BR)GSS)	25	V
Current - Drain (Idss) @ Vds (Vgs=0)	4 @ 15	mA @ V
Voltage - Cutoff (VGS off) @ Id	2 @ 10	V @ nA
Input Capacitance (Ciss) (Max) @ Vds	7 @ 15	pF @ V
Power - Max	350	mW
Operating Temperature	-55 to 150	°C
Package / Case	TO-236-3, SC-59, SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level (MSL)	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitute parts for the MMBF5459 are classified into two categories based on electrical and mechanical compatibility:

Direct Substitutes maintain the same voltage rating (25 V), N-Channel configuration, SOT-23-3 package, and surface mount technology. These parts are functionally interchangeable with the MMBF5459 in applications where the specified electrical parameters are met. Direct substitutes include MMBFJ310LT1G, MMBFJ310LT3G, MMBFU310LT1G, SMMBFJ310LT1G, and SMMBFJ310LT3G.

Similar Substitutes share the same package and mounting technology but differ in voltage rating, current characteristics, or power dissipation. These parts are suitable for applications where the design specifications allow for higher voltage ratings or different current handling capabilities. Similar substitutes include CPH3910-TL-E, MMBF4391LT1G, MMBF4392LT1G, and MMBF4393LT1G.

Key parameters determining substitution eligibility:

Voltage - Breakdown (V(BR)GSS): 25 V minimum for direct substitutes
Package / Case: TO-236-3, SC-59, SOT-23-3 required
Mounting Type: Surface Mount required
N-Channel FET configuration required
Operating Temperature: -55°C to 150°C required

Parameter Comparison

Part Number	Manufacturer	Product Status	V(BR)GSS (V)	Idss @ Vds (mA @ V)	VGS off @ Id (V @ nA)	Ciss @ Vds (pF @ V)	Power Max (mW)	Package	Mounting
MMBF5459	onsemi	Obsolete	25	4 @ 15	2 @ 10	7 @ 15	350	SOT-23-3	Surface Mount
MMBFJ309LT1G	onsemi	Active	25	30	—	—	—	SOT-23-3	Surface Mount
MMBFJ310LT1G	onsemi	Active	25	60	—	—	—	SOT-23-3	Surface Mount
MMBFJ310LT3G	onsemi	Active	25	60	—	—	—	SOT-23-3	Surface Mount
MMBFU310LT1G	onsemi	Active	25	24 @ 10	2.5 @ 1	5 @ 10	225	SOT-23-3	Surface Mount
SMMBFJ310LT1G	onsemi	Active	25	60	—	—	—	SOT-23-3	Surface Mount
SMMBFJ310LT3G	onsemi	Active	25	60	—	—	—	SOT-23-3	Surface Mount
CPH3910-TL-E	onsemi	Active	25	20 @ 5	1.8 @ 100µA	6 @ 5	400	SOT-23-3	Surface Mount
MMBF4391LT1G	onsemi	Active	30	50 @ 15	4 @ 10	14 @ 15	225	SOT-23-3	Surface Mount
MMBF4392LT1G	onsemi	Active	30	25 @ 15	2 @ 10	14 @ 15	225	SOT-23-3	Surface Mount
MMBF4393LT1G	onsemi	Active	30	5 @ 15	500mV @ 10	14 @ 15	225	SOT-23-3	Surface Mount

Engineering Selection Recommendations

For Direct Substitution (Obsolete to Active): MMBFU310LT1G is the primary direct substitute for MMBF5459. Both devices maintain 25 V breakdown voltage, N-Channel configuration, and SOT-23-3 packaging. MMBFU310LT1G is in active production status with ROHS3 compliance and unlimited moisture sensitivity rating, ensuring long-term availability and regulatory compliance.

For Automotive Applications: SMMBFJ310LT1G and SMMBFJ310LT3G are automotive-grade alternatives qualified to AEC-Q101 standard. These parts maintain the same 25 V voltage rating and SOT-23-3 package while providing automotive-level reliability and traceability.

For Higher Voltage Tolerance: MMBF4391LT1G, MMBF4392LT1G, and MMBF4393LT1G offer 30 V breakdown voltage in the same SOT-23-3 package. These parts are suitable for applications where design margins require higher voltage ratings. Selection among these three depends on required drain current characteristics: MMBF4391LT1G (50 mA), MMBF4392LT1G (25 mA), or MMBF4393LT1G (5 mA).

For Enhanced Power Dissipation: CPH3910-TL-E provides 400 mW maximum power rating compared to MMBF5459's 350 mW, maintaining 25 V voltage rating and SOT-23-3 package. This part is suitable for applications requiring additional thermal headroom.

All recommended substitutes are ROHS3 compliant with MSL 1 (Unlimited) rating and maintain surface mount SOT-23-3 packaging for direct PCB compatibility.

Frequently Asked Questions (FAQ)

Q: Can MMBFU310LT1G directly replace MMBF5459 in existing designs? A: Yes. MMBFU310LT1G maintains the same 25 V breakdown voltage, N-Channel configuration, SOT-23-3 package, and surface mount technology. The part is pin-compatible and electrically suitable for applications designed for MMBF5459 specifications.

Q: What is the difference between MMBFJ310LT1G and MMBFJ310LT3G? A: Both parts are electrically identical with 25 V rating and SOT-23-3 package. The difference is packaging format: MMBFJ310LT1G is supplied in Cut Tape (CT) & Digi-Reel format, while MMBFJ310LT3G is supplied in Tape & Reel (TR) format. Selection depends on assembly line requirements.

Q: Why are SMMBFJ310LT1G and SMMBFJ310LT3G listed as substitutes? A: These automotive-grade parts (AEC-Q101 qualified) maintain the same 25 V voltage rating and SOT-23-3 package as MMBF5459. They are suitable for applications requiring automotive-level reliability and traceability, with the same packaging format distinction as the standard MMBFJ310 variants.

Q: Can I use MMBF4392LT1G as a substitute for MMBF5459? A: MMBF4392LT1G is a similar substitute with higher voltage rating (30 V vs. 25 V) and different current characteristics (25 mA Idss vs. 4 mA). It is suitable only if your application design allows for higher voltage tolerance and the different drain current specification does not affect circuit performance.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts are ROHS3 compliant with MSL 1 (Unlimited) moisture sensitivity rating, meeting current environmental and regulatory requirements.

Q: What packaging options are available for direct substitutes? A: Direct substitutes are available in two packaging formats: Cut Tape (CT) & Digi-Reel (MMBFJ310LT1G, MMBFU310LT1G, SMMBFJ310LT1G) and Tape & Reel (TR) (MMBFJ310LT3G, SMMBFJ310LT3G). Selection depends on assembly equipment and production volume requirements.

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