J201 JFET Datasheet

J201 JFET Datasheet
J201 JFET Datasheet

J201 JFET specification

  • J201 is a general-purpose N-channel amplifier JFET device
  • Drain to gate voltage (VDG) is 40V
  • Gate to source voltage (VGS) is –40V
  • Gate to source cutoff voltage (VGS (OFF)) is -0.3 to -1.5V
  • Drain gate forward current (IGF) is 50mA
  • Power dissipation is (PD) is 625mW
  • Zero gate voltage drain current (IDSS) is 2 to 1mA
  • Junction temperature (TJ) is between -65 to 150℃
  • Thermal resistance of ambient is 125℃/W
  • Forward transfer admittance (YFS) is 500umhos
  • Low noise
  • High gain
  • High impedance


Pin Number Pin Name Description
1 Gate The gate terminal is used to trigger the device
2 Source In the source, terminal current flows out from the JFET 
3 Drain   The drain terminal is the current inlet of the JFET device


J201 JFET package

The J201 JFET has a TO-92 package, it is a general-purpose device package mainly used for low-power applications.

TO-92 package is made of epoxy material, which is best at thermal capacity and it is more lite weight.

The J201 JFET transistor had more miniature applications, so the TO-92 package is most suitable for it.

J201 JFET electrical specification and application description

In this section, we explain the electrical specifications of the J201 JFET transistor, which is been helpful for a better understanding of this device for the replacement process.

Voltage specs

The terminal voltage specs of J201 JFET are a drain to gate voltage is 40V and gate to source voltage is -40V.

The gate to source cutoff voltage is -0.3V to -1.0V,

Overall voltage specifications of J201 JFET show that it is a DIY device mainly used for low-power applications.

Current specs

The forward gate current value of J201 JFET is 50mA,

Zero gates voltage drain current

The zero gate voltage drain current value is 0.2 to 1.0mA, it is the current value under the special condition where the gate voltage is zero.

Dissipation specs

The power dissipation is 625mW for the J201 JFET device, it is the medium value for a semiconductor device.

Junction temperature

The junction temperature of J201 JFET is -55 to +150℃.

Thermal resistance

The thermal resistance of the ambient J201 JEFT device is 125℃/W


If you need the datasheet in pdf please click this link


The J201 JFET had equivalents such as 2N4338, 2N4339, 2N4340, 2N5458, NTE458, and J174. All of these JFET devices had the same electrical specifications.

SMD equivalent of J201 JFET

The MMBFJ201 (SOT-23) is the SMD equivalent of J201 JFET.

J201 vs 2N5457 vs 2N4338

In the table below we list and compare the electrical specifications of J201, 2N5457, and 2N4338 JFET devices.

This comparison is really helpful for the replacement process and they are helpful for a better understanding.


Characteristics curves of J201 JFET 

output characteristics of the J201 JFET
output characteristics of the J201 JFET

The figures show the output characteristics of the J201 JFET device, the graph is plotted with drain current vs drain to source voltage.

At a fixed cutoff voltage, the drain current increases at the different gates to source voltage values. The drain current increases and become constant and then become infinite.

transfer characteristics of J201 JFET
transfer characteristics of J201 JFET

The figure shows the transfer characteristics of J201 JFET, the graph plots with drain current vs gate to source voltage.

At a fixed drain to source voltage values and two different gate-to-source cutoff voltages, the drain current dips towards the negative value with respect to the gate to source voltage.

Applications of J201 JFET

  • Sensor circuits
  • Preamp circuits
  • Laser detector circuits
  • Data amplifier circuits
  • Infrared detection systems
  • Buffer circuits
  • Voltage booster circuits
  • Low-level audio amplifier circuit

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