The MOSFET or Metal Oxide Silicon Field Effect Transistor is a voltage-controlled device, made with the controlled oxidation of a ‘Si’ semiconductor material. These transistors are used in both analog & digital circuits. When the voltage is applied at the gate terminal of the MOSFET, then it controls the flow of current at the source & drain terminals because the gate terminal functions like a control valve. MOSFETs are manufactured by different manufacturers around the world like Infineon, Diodes Incorporated STMicroelectronics, Nexperia, Vishay, Renesas, etc. From that, Infineon technologies manufactured different IRF series MOSFETs like IRF3205, IRFB4110, IRFZ44N, IRF840, IRF540, IRFP2907, etc. This article discusses one of the IRF series MOSFETs like IRF840 MOSFET – pin configuration, specifications, and its applications.
What is IRF840 MOSFET?
The IRF840 is an N-channel power MOSFET that is mainly used to switch the loads up to 500Volts that consume up to 8A of current. This MOSFET is a high voltage & fast switching device that needs 10V across the gate (G) terminal to start the conduction process. This MOSFET has three terminals like gate (G), drain (D) & source (S) where the external circuits are simply connected through these terminals.
In this N-channel MOSFET, the conduction process can be implemented through the flow of electrons. The majority of charge carriers of n-channel MOSFET devices are electrons whereas, in the p-channel MOSFET, the majority of charge carriers are holes.
Pin Configuration:
The pin configuration of IRF840 MOSFET with a symbol is shown below. This MOSFET includes three pins and each pin and its functionality is discussed below.
IRF840 MOSFET PIn Configuration
- Pin1 (Source): The current supplies out from this pin.
- Pin2 (Gate): This terminal functions like the trigger to control the MOSFET biasing.
- Pin3 (Drain): The drain pin allows the flow of current so, it is the input terminal of the MOSFET.
Features & Specifications:
The features and specifications of IRF840 MOSFET include the following.
- It is an N-Channel Power MOSFET.
- Its rise time (ts) is 23nS.
- Its fall time (tf) is 20nS.
- It is manufactured by STMicroelectronics.
- The category of the Product is MOSFET.
- Dynamic dv/dt rating.
- Fast switching & Ease of paralleling.
- The switching speed is nanoseconds.
- Input impedance is high.
- Its technology is Si.
- Its mounting style is Through Hole.
- Its package or case is TO-220-3.
- The polarity of the transistor is N-Channel.
- The number of channels – 1.
- The mode of the channel is enhancement.
- Tube packaging.
- Its height is 9.15 mm.
- Its length is 10.4 mm.
- Its width is 4.6 mm.
- Its series is IRF.
- The gate threshold voltage or VGS-th is 10V.
- Drain Current Continuously or ID is 8A.
- The resistance of the Drain Source or RDS is 0.85 Ohms or 850 mOhms.
- The Drain to Source breakdown voltage (Vds )is 500V.
- Gate-Source Voltage is – 20 V, + 20 V.
- Operating Temperature ranges from – 65 C to + 150 C.
- Power Dissipation (Pd) is 125 W.
- Turn-On Delay Time Typically is 10 ns.
- The pulsed drain current or IDM is 32A.
- The total gate charge or Qg is 63nC.
- Input capacitance or Ciss is 1300pF.
- Reverse recovery time or trr is 460 to 970ns.
- Junction temperature or TJ ranges from -55 to 150℃.
IRF840 MOSFET Circuit
The IRF840 MOSFET circuit used to control the DC motor speed is shown below. The required components to make this circuit are; IRF840 MOSFET, a DC motor, a 12V battery, and a variable resistor.
IRF840 MOSFET Circuit
The connections of this circuit follow as; the first pin of the variable resistor is connected to the negative terminal of the battery, the second output pin is connected to the gate pin of MOSFET, and the third pin is connected to the positive terminal of the battery. The positive supply of a battery is connected to the drain terminal of MOSFET. Both the source terminal of MOSFET and the negative terminal of a battery are connected to DC motor positive and negative terminals. Now the circuit is connected completely.
The working of this circuit follows as; the variable resistor output goes to the MOSFET gate terminal which works like a valve so that the voltage from the source terminal of MOSFET is given to the DC motor so that it turns ON the DC motor. Based on the motor speed, we can control this motor by rotating the variable resistor.
Equivalent IRF840 MOSFETs
The equivalent IRF840 MOSFETs are; IRF840A, IRF841, IRF843, IRF842, IRFI840G, IRFS841, IRFS840, STP8NA50, 2SK1158, 2SK554, 2SK1566, 2SK1805, 2SK1567, 2SK2117, 2SK2116, 2SK2118, IRF74, 2SK2175, etc. The electrical specifications of these MOSFETs are approximately the same, thus we can replace them very easily. But before replacing these MOSFETs, we have to cross-check the pin configuration.
How to Safely Run IRF840 MOSFET in a Circuit?
To run IRF840 MOSFET safely in a circuit, it is better to utilize a component always on its maximum limits. The maximum load voltage of IRF840 MOSFET can handle 500V so do not drive any load above 400V. The maximum drain current is 8A so do not drive a load above 6.4A. This MOSFET should be operated in temperatures> -55oC < +150oC.
Applications
The applications of IRF840 MOSFET include the following.
- IRF840 is applicable where you need to drive maximum load voltage upto 500V with upto 8A of load current.
- This MOSFET is also used where high-speed switching is essential.
- It can be used directly at the output of microcontrollers, ICs & different electronic platforms like
- Raspberry Pi & Arduino to drive different loads.
- It can also be used to design high-power audio amplifiers.
- Motor drivers circuits.
- Switching converter.
- Switching regulator.
- DC-DC converter.
- Flasher circuits.
- UPS.
- LED dimmer circuits.
- DC motor driver system.
- High power switching.
- Solar power applications.
- AC motor driver system.
- Battery charger system.
- Relay drivers.
- Inverter Circuits.
- High-Speed switching applications.
- It is used to control the speed of motors & LED flashers or dimmers.
Please refer to this link for IRF840 MOSFET Datasheet , MX1508 DC Motor Driver.
Please refer to this for How to Select a Transistor.
Thus, this is an overview of an IRF840 MOSFET – pin configuration, features, specifications, circuit, working & its applications. IRF840 MOSFET is mainly designed for high-voltage applications including high-speed switching capabilities. So this MOSFET can be used for both amplification & switching purposes. This MOSFET can be utilized in many high-voltage applications like motor controllers, power supplies, UPS, etc. Here is a question for you, what is the function of a MOSFET?