2N4393 JFET N-Channel Transistor: Equivalent & Substitute Parts

Part Overview

The 2N4393 is an N-Channel JFET transistor manufactured by Vishay Siliconix, rated for 40 V breakdown voltage with 1.8 W maximum power dissipation in a TO-206AA (TO-18) metal can package. This component is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications. Substitute parts must maintain electrical compatibility across voltage ratings, drain current characteristics, and thermal operating ranges while accommodating packaging and compliance requirements.

Key Parameters

Parameter	Value	Unit
Voltage - Breakdown (V(BR)GSS)	40	V
Current - Drain (Idss) @ Vds (Vgs=0)	5 mA @ 20 V	mA
Voltage - Cutoff (VGS off) @ Id	500 mV @ 1 nA	mV
Input Capacitance (Ciss) (Max) @ Vds	14 pF @ 20 V	pF
Resistance - RDS(On)	100	Ohms
Power - Max	1.8	W
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	TO-206AA, TO-18-3 Metal Can	—

Substitute Part Grouping Explanation

Substitution eligibility for the 2N4393 is determined by the following electrical and mechanical criteria:

Voltage Rating: V(BR)GSS must equal or exceed 40 V
FET Type: N-Channel configuration required
Package Compatibility: TO-18 or TO-206AA metal can packages acceptable
Mounting: Through-hole technology required
Operating Temperature: Must support -65°C to 200°C range
Drain Current (Idss): Acceptable range 5–8 mA @ specified Vds
On-Resistance (RDS(On)): 60–100 Ohms acceptable for circuit operation

Three substitute parts meet these criteria: 2N4858 (Microchip Technology), 2N4858A (Central Semiconductor Corp), and MV2N4393 (Microchip Technology). All maintain the 40 V voltage rating, N-Channel configuration, and TO-18 packaging. The 2N4858 and 2N4858A offer reduced power dissipation (360 mW) compared to the original 1.8 W rating, with lower on-resistance (60 Ohms vs. 100 Ohms).

Parameter Comparison

Parameter	2N4393 (Original)	2N4858	2N4858A	MV2N4393
Manufacturer	Vishay Siliconix	Microchip Technology	Central Semiconductor Corp	Microchip Technology
Product Status	Obsolete	Active	Active	Active
FET Type	N-Channel	N-Channel	N-Channel	N-Channel
V(BR)GSS	40 V	40 V	40 V	—
Idss @ Vds	5 mA @ 20 V	8 mA @ 15 V	8 mA @ 15 V	—
VGS(off) @ Id	500 mV @ 1 nA	4 V @ 500 pA	800 mV @ 0.5 nA	—
Ciss (Max) @ Vds	14 pF @ 20 V	18 pF @ 10 V	10 pF @ 10 V	—
RDS(On)	100 Ohms	60 Ohms	60 Ohms	—
Power - Max	1.8 W	360 mW	360 mW	—
Operating Temperature	-65 to 200°C	-65 to 200°C	-65 to 200°C	—
Package / Case	TO-206AA, TO-18-3	TO-206AA, TO-18-3	TO-206AA, TO-18-3	—
RoHS Status	Non-compliant	Non-compliant	ROHS3 Compliant	Non-compliant

Engineering Selection Recommendations

2N4858 (Microchip Technology): Active product status with confirmed availability (2240 pcs in stock). Maintains 40 V voltage rating and TO-18 packaging. Lower power dissipation (360 mW) and reduced on-resistance (60 Ohms) provide improved thermal performance. RoHS non-compliant status matches original part. Suitable for applications where power dissipation reduction is acceptable.

2N4858A (Central Semiconductor Corp): Active product status with confirmed availability (1430 pcs in stock). Meets all electrical requirements with 40 V rating and TO-18 packaging. ROHS3 compliance provides regulatory advantage for new designs and procurement. Lower power dissipation and on-resistance match 2N4858 specifications. Recommended for applications requiring RoHS compliance.

MV2N4393 (Microchip Technology): Active product status with confirmed availability (779 pcs in stock). Direct part number variant from Microchip Technology. Limited detailed specifications provided in datasheet. RoHS non-compliant. Suitable for direct replacement where manufacturer continuity is prioritized.

Frequently Asked Questions (FAQ)

Q: Can 2N4858 or 2N4858A replace 2N4393 in existing circuits?

A: Yes. Both parts maintain the 40 V breakdown voltage rating, N-Channel configuration, and TO-18 packaging required for mechanical and electrical compatibility. The reduced on-resistance (60 Ohms vs. 100 Ohms) and lower power dissipation (360 mW vs. 1.8 W) represent improved performance characteristics. Circuit operation remains valid within the specified parameter ranges.

Q: What is the difference between 2N4858 and 2N4858A?

A: Both parts share identical electrical specifications (40 V rating, 8 mA Idss, 60 Ohms RDS(On), 360 mW power rating). The primary distinction is RoHS compliance: 2N4858A is ROHS3 compliant, while 2N4858 is non-compliant. For new designs or procurement requiring regulatory compliance, 2N4858A is the appropriate selection.

Q: Is MV2N4393 a direct equivalent to 2N4393?

A: MV2N4393 is a Microchip Technology variant with active product status. Limited detailed specifications are available in standard datasheets. Consult manufacturer documentation for complete electrical parameter verification before circuit implementation.

Q: Are all substitute parts available in TO-18 packaging?

A: Yes. All substitute parts (2N4858, 2N4858A, MV2N4393) are supplied in TO-18 metal can packages, maintaining mechanical compatibility with the original 2N4393 TO-206AA (TO-18) specification.

Q: What is the impact of lower power dissipation in 2N4858 and 2N4858A?

A: The 360 mW rating (vs. 1.8 W original) indicates reduced thermal generation under identical operating conditions. This improves thermal stability and reduces heat management requirements. Verify that circuit power dissipation does not exceed 360 mW at maximum operating temperature to ensure reliable operation.

Q: Can these parts be used interchangeably in production?

A: Electrical interchangeability is confirmed across all three substitutes for the specified parameter ranges. Mechanical compatibility (TO-18 packaging, through-hole mounting) is maintained. Verify RoHS compliance requirements for your application: 2N4858A is ROHS3 compliant; 2N4858 and MV2N4393 are non-compliant.

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