MMBF5458 Equivalent & Substitute Parts

Part Overview

The MMBF5458 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 MMBF5458 is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity.

Key Parameters

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

Substitute Part Grouping Explanation

Substitution eligibility for the MMBF5458 is determined by the following criteria:

Direct Substitutes maintain identical or superior electrical performance within the same package footprint (SOT-23-3). These parts share the same voltage rating (25 V), N-Channel configuration, and surface mount characteristics. Direct substitutes include MMBFJ310LT1G, MMBFJ310LT3G, MMBFU310LT1G, SMMBFJ310LT1G, and SMMBFJ310LT3G. These parts are all active products with current manufacturing status.

Similar Substitutes provide functional equivalence with minor parameter variations that remain within acceptable design tolerances. These include CPH3910-TL-E, MMBF4391LT1G, MMBF4392LT1G, and MMBF4393LT1G. While these parts maintain the SOT-23-3 package and N-Channel JFET configuration, they may feature different voltage ratings (30 V) or current characteristics that require circuit-level verification.

The substitution logic is based on:

Identical package type (SOT-23-3 / TO-236-3)
N-Channel JFET configuration
Voltage rating compatibility (25 V or higher)
Surface mount technology
RoHS3 compliance and MSL-1 rating

Parameter Comparison

Part Number	Manufacturer	Status	V(BR)GSS (V)	Idss @ Vds (mA)	VGS off (V)	Ciss (pF)	Power Max (mW)	Package
MMBF5458	onsemi	Obsolete	25	2 @ 15 V	1 @ 10 nA	7 @ 15 V	350	SOT-23-3
MMBFJ309LT1G	onsemi	Active	25	—	—	—	—	SOT-23-3
MMBFJ310LT1G	onsemi	Active	25	—	—	—	—	SOT-23-3
MMBFJ310LT3G	onsemi	Active	25	—	—	—	—	SOT-23-3
MMBFU310LT1G	onsemi	Active	25	24 @ 10 V	2.5 @ 1 nA	5 @ 10 V	225	SOT-23-3
SMMBFJ310LT1G	onsemi	Active	25	—	—	—	—	SOT-23-3
SMMBFJ310LT3G	onsemi	Active	25	—	—	—	—	SOT-23-3
CPH3910-TL-E	onsemi	Active	25	20 @ 5 V	1.8 @ 100 µA	6 @ 5 V	400	SOT-23-3
MMBF4391LT1G	onsemi	Active	30	50 @ 15 V	4 @ 10 nA	14 @ 15 V	225	SOT-23-3
MMBF4392LT1G	onsemi	Active	30	25 @ 15 V	2 @ 10 nA	14 @ 15 V	225	SOT-23-3
MMBF4393LT1G	onsemi	Active	30	5 @ 15 V	500 mV @ 10 nA	14 @ 15 V	225	SOT-23-3

Engineering Selection Recommendations

For Direct Replacement: MMBFJ310LT1G, MMBFJ310LT3G, MMBFU310LT1G, SMMBFJ310LT1G, and SMMBFJ310LT3G are all active products with current manufacturing status. These parts maintain the 25 V voltage rating and SOT-23-3 package compatibility. All substitute parts carry RoHS3 compliance and MSL-1 moisture sensitivity rating, matching the original device specifications.

For Automotive Applications: SMMBFJ310LT1G and SMMBFJ310LT3G are qualified to AEC-Q101 automotive standards, providing enhanced reliability for automotive-grade designs.

For Higher Voltage Tolerance: MMBF4391LT1G, MMBF4392LT1G, and MMBF4393LT1G offer 30 V breakdown voltage, providing additional design margin in applications where voltage stress may approach the 25 V limit. These parts maintain the same SOT-23-3 package and surface mount configuration.

All substitute parts are manufactured by onsemi and comply with ROHS3 and REACH requirements, matching the regulatory status of the original MMBF5458.

Frequently Asked Questions (FAQ)

Q: Can MMBFJ310LT1G directly replace MMBF5458 in existing designs? A: Yes. MMBFJ310LT1G maintains the same 25 V voltage rating, N-Channel JFET configuration, and SOT-23-3 package footprint. Both parts are RoHS3 compliant with MSL-1 rating.

Q: What is the difference between MMBFJ310LT1G and MMBFJ310LT3G? A: Both parts are electrically identical. The primary difference is packaging: MMBFJ310LT1G is supplied in Cut Tape (CT) & Digi-Reel format, while MMBFJ310LT3G is supplied in Tape & Reel (TR) format. Selection depends on assembly process requirements.

Q: Why would I choose MMBFU310LT1G over MMBFJ310LT1G? A: MMBFU310LT1G provides measurable drain current (24 mA @ 10 V) and cutoff voltage specifications (2.5 V @ 1 nA), offering more complete parametric data for circuit design. It also features lower input capacitance (5 pF @ 10 V) compared to the original 7 pF specification.

Q: Are the MMBF4391/4392/4393 series suitable replacements? A: These parts are functionally similar but feature 30 V breakdown voltage instead of 25 V. They are suitable for applications where higher voltage margin is beneficial, but circuit-level verification is required due to different current and capacitance characteristics.

Q: What is the significance of the SMMBFJ310 automotive-grade variants? A: SMMBFJ310LT1G and SMMBFJ310LT3G carry AEC-Q101 automotive qualification, making them suitable for automotive applications requiring enhanced reliability and traceability standards.

Q: Do all substitute parts maintain the same thermal operating range? A: Yes. All listed substitute parts operate across -55°C to 150°C junction temperature, matching the original MMBF5458 specification.

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