Introduction to 2n7002

Introduction to 2n7002

• 2n7002 is an N-Channel MOSFET which is mainly designed to reduce on-state resistance.
• It mainly consists of three terminals called source, gate and drain. Unlike normal BJT, this is a voltage controlled device, in which voltage applied at the gate terminal is used to control the conductivity between source and drain terminals.
• Source, gate and drain of this MOSFET are analogous to emitter, base and collector of BJT.
• The conducting path between source and drain is referred as channel whose length is controlled by the input voltage applied at the gate terminal.
• 2n7002 is an ideal choice for high efficiency power management applications because it comes with an ability to maintain high switching performance.
• It encompasses low gate threshold voltage and low input capacitance and comes in surface mount package.
• High saturation current capability makes it rugged and reliable.
• This high cell density MOSFET are designed using DMOS technology.

• 2n7002 is an ideal choice for the applications requiring 400 mA DC and is capable of delivering pulsed current up to 4 A.
• It doesn't conduct under normal operating conditions i.e. Vgs=0 and is considered as OFF. It will only conduct when there is small voltage applied at the gate terminal.
• As it is an N-Channel MOSFET so conductivity is carried out by the movement of electrons rather than hole.
• It widely replaces BJT in many applications, because it requires no biasing at the gate terminals, means gate draws no current. However, small surge current is required to charge the capacitance at the gate terminal.
• There is no need of current limiting resistor at the gate terminal because gate draws no current. However, protection gate resistor is used for circuits containing external gate vulnerability.

2n7002 Pinout

• Insulation layer is existed between gate and body of the transistor.
• Gate draws no current and is practically isolated from drain and source.

2n7002 Working

• Movement of electrons plays an important role in defining the nature of any MOSFET. Conduction between drain and source is carried out by the free movement of electrons.
• Voltage applied at the gate terminal allows the electrons to flow from source to drain terminals.
• This is an N-Channel MOSFET where drain and source are composed of N type material while body and substrate is composed of P type material.
• Applying positive voltage at the gate terminal will attract the electrons available at the P type semiconductor substrate material.
• The gate of this transistor is mainly composed of poly silicon.
• Adding Silicon Dioxide on the substrate layer gives the typical metal oxide semiconductor construction.
• Silicon Dioxide is a dielectric and behaves like a capacitor where one of its electrodes  is replaced by the semiconductor.
• Applying positive voltage at the MOS structure will change the charge distribution in the semiconductor.  When positive voltage is applied the holes present in the oxide layer will observe a force and allow the holes to move downward.  As a result, bound negative charges that are associated with the acceptor atoms will accumulate the depletion region.
• The overall conductivity of the channel between source and drain will increase with the overdose of free electrons in the P type substrate which ultimately helps in inverting the electrical properties of the P type substrate, allowing the substrate to change into N type material.
• The positive voltage applied at the gate terminal controls the number of electrons. Increasing the positive voltage at the gate terminal will attract more electrons which ultimately helps in widening the channel path between source and drain terminals. Hence, conductive of this MOSFET is directly proportional to the intensity of positive voltage applied at the gate terminal.

Absolute Maximum Ratings

• Drain-Source and Drain-Gate voltage is 60 V.
• Maximum power it can dissipate is 200 mW.
• Maximum lead temperature in order to conduct efficient soldering is 300 ºC.
• These are the stress ratings, which if increased from absolute maximum ratings, can damage the device.
• Similarly, if these stresses are applied for extended period of time, they can effect device reliability.

Applications

• It is useful for motor control.
• Power management applications use this MOSFET because it comes with high switching performance.
• It is an ideal choice for minimizing on-state resistance.
• This MOSFET product is particularly suited for low current and low voltage applications such as power MOSFET gate drivers and other switching applications.