2N4118A-E3 Equivalent & Substitute Parts

Part Overview

The 2N4118A-E3 is an N-Channel JFET transistor manufactured by Vishay Siliconix, rated for 40 V breakdown voltage and 300 mW power dissipation in a TO-206AF (TO-72) metal can package. This device is classified as obsolete, making equivalent substitutes necessary for new designs and production continuity. The part operates across a wide temperature range from -55°C to 175°C and is ROHS3 compliant.

Key Parameters

Parameter	Value	Unit
Voltage - Breakdown (V(BR)GSS)	40	V
Current - Drain (Idss) @ Vds (Vgs=0)	80 µA @ 10 V	µA
Voltage - Cutoff (VGS off) @ Id	1 V @ 1 nA	V
Input Capacitance (Ciss) (Max) @ Vds	3 pF @ 10 V	pF
Power - Max	300	mW
Operating Temperature Range	-55 to 175	°C
Package / Case	TO-206AF, TO-72-4 Metal Can	—
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution eligibility for the 2N4118A-E3 is determined by the following critical parameters:

FET Type: N-Channel (required match)
Voltage - Breakdown (V(BR)GSS): Minimum 40 V (equal or higher acceptable)
Power - Max: Minimum 300 mW (equal or higher acceptable)
Mounting Type: Through Hole (required match)
Package compatibility: TO-72 or equivalent metal can packages

The two identified substitutes meet these core criteria while offering active product status and improved availability.

Parameter Comparison

Parameter	2N4118A-E3 (Main)	2N3821 (Substitute)	2N4858A (Substitute)
Manufacturer	Vishay Siliconix	Microchip Technology	Central Semiconductor Corp
FET Type	N-Channel	N-Channel	N-Channel
Voltage - Breakdown (V(BR)GSS)	40 V	50 V	40 V
Current - Drain (Idss) @ Vds (Vgs=0)	80 µA @ 10 V	2.5 mA @ 15 V	8 mA @ 15 V
Voltage - Cutoff (VGS off) @ Id	1 V @ 1 nA	4 V @ 0.5 nA	800 mV @ 0.5 nA
Input Capacitance (Ciss) (Max) @ Vds	3 pF @ 10 V	6 pF @ 15 V	10 pF @ 10 V
Power - Max	300 mW	300 mW	360 mW
Operating Temperature Range	-55 to 175°C	-55 to 200°C	-65 to 200°C
Package / Case	TO-206AF, TO-72-4 Metal Can	TO-206AF, TO-72-4 Metal Can	TO-206AA, TO-18-3 Metal Can
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

2N3821 (Microchip Technology)

The 2N3821 offers a 50 V breakdown voltage rating, exceeding the 2N4118A-E3 specification. It maintains identical power rating (300 mW) and operates across an extended temperature range (-55 to 200°C). The part is actively manufactured and available in high inventory. However, it is RoHS non-compliant, which may restrict use in applications requiring RoHS certification. The TO-72 package provides direct mechanical compatibility.

2N4858A (Central Semiconductor Corp)

The 2N4858A matches the 40 V breakdown voltage of the original part and provides higher power dissipation capability (360 mW). It is ROHS3 compliant and operates across an extended temperature range (-65 to 200°C). The part is actively produced with strong inventory availability. The TO-18 package differs from the TO-72, requiring PCB layout verification for pin compatibility and thermal performance.

Frequently Asked Questions (FAQ)

Q: Can the 2N3821 directly replace the 2N4118A-E3 in all applications?

A: The 2N3821 meets the core electrical requirements (N-Channel, 50 V breakdown, 300 mW power, TO-72 package). However, RoHS non-compliance may disqualify it for applications requiring RoHS certification. Verify compliance requirements before selection.

Q: What is the primary difference between the 2N3821 and 2N4858A substitutes?

A: The 2N3821 maintains the TO-72 package form factor and offers higher voltage rating (50 V). The 2N4858A uses a TO-18 package and provides higher power dissipation (360 mW) with ROHS3 compliance. Package selection depends on PCB layout constraints and compliance requirements.

Q: Is the TO-18 package of the 2N4858A compatible with TO-72 footprints?

A: No. The TO-18 and TO-72 are distinct metal can packages with different pin configurations and physical dimensions. PCB redesign is required if selecting the 2N4858A as a substitute.

Q: Which substitute is recommended for RoHS-compliant applications?

A: The 2N4858A is ROHS3 compliant. The 2N3821 is RoHS non-compliant and unsuitable for applications requiring RoHS certification.

Q: Do the substitutes maintain the same operating temperature range as the 2N4118A-E3?

A: Both substitutes extend the upper operating temperature limit to 200°C, exceeding the original part's 175°C maximum. The 2N4858A extends the lower limit to -65°C. These extended ranges provide additional design margin.

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