2N4391 TO-18 3L ROHS

Jfets Overview

The 2N4391 is an N-channel silicon small-signal Junction Field-Effect Transistor (JFET) manufactured by Interfet, a subsidiary of Vishay. It is housed in a hermetically sealed TO-18 metal can package with three leads. The device features a gate-to-source breakdown voltage ($BV_{GSS}$) of -40 V minimum and a drain-to-source saturation current ($I_{DSS}$) ranging from 50 µA to 500 µA. The gate-to-source cutoff voltage ($V_{GS(off)}$) is specified between -4 V and -10 V. It operates within a temperature range of -55 °C to +200 °C and has a maximum power dissipation of 1.8 W.

Jfets Feature Summary

• Utilizes Interfet N0132S geometry for low noise performance, typically 1.2 nV/√Hz.
• Features extremely low gate leakage currents, typically less than 50 pA at room temperature.
• Hermetically sealed TO-18 package construction suitable for military and high-reliability applications.

Jfets Applications

• Low on-resistance analog switches
• Chopper circuits
• Commutator designs

Jfets Procurement Notes

Verify the manufacturer origin, as the 2N4391 specification is primarily associated with Interfet/Vishay. Confirm that the specific unit matches the required $I_{DSS}$ binning and $V_{GS(off)}$ limits. Ensure the TO-18 package lead configuration corresponds to the standard pinout: Pin 1 Source, Pin 2 Gate, Pin 3 Drain when viewed from the bottom.

Jfets Selection Notes

Select this component for precision analog switching where low noise and minimal gate leakage are critical. Compare against the 2N4392 and 2N4393 variants if different cutoff voltage ranges or saturation currents are required. Ensure the design accommodates the TO-18 through-hole mounting constraints and thermal management requirements for the 1.8 W dissipation limit.

Jfets Part Context

The 2N4391 belongs to the 2N/PN/SST4391 series of N-channel JFETs. This family includes the 2N4392 and 2N4393, which share similar geometries but differ in electrical parameters such as $V_{GS(off)}$ and $I_{DSS}$. The series is designed specifically for switch, chopper, and commutator applications requiring high reliability and low noise characteristics.

Jfets Replacement Considerations

Direct substitutes include the 2N4392 and 2N4393 from the same Interfet/Vishay series, provided their specific $V_{GS(off)}$ and $I_{DSS}$ ranges align with the circuit requirements. PN4391 denotes the P-channel counterpart and is not electrically interchangeable. Other generic JFETs may require significant circuit redesign due to parameter variations.