MPF4393G N-Channel JFET Equivalent & Substitute Parts

Part Overview

The MPF4393G is an N-Channel JFET transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. It features a 30 V drain-to-source voltage rating, 350 mW power dissipation, and is housed in a TO-92 through-hole package. The device is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and production continuity.

Substiute Parts

MPF4393G

onsemiIn Stock: 1241MPF4393G Datasheet

Current PartRFQ

BF256B

onsemiIn Stock: 39931BF256B Datasheet

DirectRFQ

PN4393 TRA

Central Semiconductor CorpIn Stock: 2725PN4393 TRA Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MPF4393G is determined by the following critical parameters:

• FET Configuration: N-Channel topology
• Voltage Rating: Minimum Vdss of 30 V or greater
• Drain Current (Idss): Nominal 5 mA at specified Vds
• Gate Cutoff Voltage (VGS off): Approximately 500 mV
• On-State Resistance (RDS(On)): 100 Ohms nominal
• Package Type: TO-92-3 through-hole form factor
• Operating Temperature Range: -65°C to 150°C minimum

Two substitute parts meet these criteria:

1. BF256B (onsemi): Direct manufacturer alternative with identical voltage and resistance specifications, active product status, and equivalent package.
2. PN4393 TRA (Central Semiconductor Corp): Similar N-Channel JFET with higher voltage rating (40 V) and increased power rating (625 mW), maintaining core electrical parameters and package compatibility.

Parameter Comparison

Engineering Selection Recommendations

BF256B is the primary substitute for direct replacement applications. It is manufactured by onsemi, the original MPF4393G supplier, maintains identical voltage and resistance specifications, and holds active product status with ROHS3 compliance. This part is suitable for applications requiring exact electrical equivalence with modern supply chain availability.

PN4393 TRA serves as an alternative for applications where higher voltage margin (40 V vs. 30 V) and increased power dissipation capability (625 mW vs. 350 mW) provide design benefits. This part is manufactured by Central Semiconductor Corp and maintains active status with ROHS3 compliance. The higher voltage rating provides additional design headroom in circuits operating near the 30 V limit of the original device.

Both substitutes are available in the same TO-92-3 package, ensuring mechanical and thermal compatibility with existing PCB layouts and thermal management designs.

Frequently Asked Questions (FAQ)

Q: Can BF256B replace MPF4393G in all applications? A: BF256B is electrically equivalent to MPF4393G across all specified parameters: 30 V Vdss, 100 Ohm RDS(On), and identical operating temperature range. Mechanical compatibility is confirmed through identical TO-92-3 packaging. Direct substitution is supported.

Q: What is the advantage of using PN4393 TRA over BF256B? A: PN4393 TRA provides a 40 V voltage rating compared to 30 V, and 625 mW power rating compared to 350 mW. These higher ratings offer design margin in circuits approaching the original device limits. Core electrical parameters (Idss, VGS off, RDS(On)) remain compatible.

Q: Are all three parts pin-compatible? A: Yes. All three devices use the TO-92-3 package with identical pin configuration for N-Channel JFET applications. PCB layout modifications are not required.

Q: What is the difference between the Idss specifications listed for these parts? A: Idss values are measured at different Vds conditions (MPF4393G at 15 V, BF256B at unspecified voltage, PN4393 TRA at 20 V). These measurements reflect device characterization at different operating points and do not indicate incompatibility. The nominal drain current behavior remains consistent across the specified voltage range.

Q: Are these parts RoHS compliant? A: BF256B and PN4393 TRA are both ROHS3 compliant. The original MPF4393G RoHS status is not specified in available documentation. Both active substitutes meet current environmental compliance requirements.

Q: Can I use these parts interchangeably in existing designs? A: Yes, within the specified electrical and thermal operating ranges. All three parts share N-Channel JFET topology, compatible voltage and current ratings, and identical package form factor. Design verification should confirm that application-specific performance requirements are met by the selected substitute.