The IRFZ44N is an n-channel enhancement mode power MOSFET manufactured by International Rectifier Corporation, in a TO-220 package. It has a continuous drain current of 49 A at 25 °C, and 35 A at 100 °C, making it an ideal component for switched mode power supplies, and general switching applications. This MOSFET has an operating temperature of 175 °C and therefore a heatsink is vital.
The pin configuration is very simple as the package conforms to JEDEC TO-220AB outline. The centre pin is drain, the left pin is gate, the right pin is source, and the metal tab is drain.
It can control a DC fan, without the need for a relay. It can also be utilised in an h-bridge circuit to make a motor controller for Arduino projects. These transistors are also utilised in general MOSFET driver applications.
It could be utilised as an LED driver; however, it would be overkill because this transistor is capable of delivering 49 amps!
There are many equivalent replacements to this MOSFET, and one such is the NTE2395. However, the IRFZ44N is widely and readily available from many electronics shops including places such as eBay on wholesale.
Switching Circuit Diagram
As you can see, the circuit is very simple and it is easy to implement this MOSFET as a switching device. The load can be almost any kind of load, from car headlights to fan control.
How does a MOSFET work?
At first, the labelling of a MOSFET appears confusing to beginners, because the source connects to ground and the drain to the positive power rail. However, it all makes sense when you realise that it represents the flow of electrons. This is an n-channel MOSFET, which means that the charge carriers are electrons. Electrons are negative and move from the negative rail to the positive rail. Many GCSE students tend to trip up on that one.
A MOSFET is a voltage-controlled device, which means that the gate requires a positive voltage for it to conduct and switch on. The voltage creates an electric field, which increases the number of charge carriers.
According to the documentation the absolute maximum gate-source voltage parameters are ±20 V, however, a voltage higher than the source usually gets the transistor to start conducting.
A MOSFET has an insulated gate junction, which also exhibits a capacitance. When a voltage is applied, the charge remains at the junction for a long time keeping the transistor in a conducting state. To prevent this from happening a pull-down resistor between the gate and the source are required, which discharges any residual charge.
These transistors are relatively inexpensive and are usually for sale at Farnell and eBay. They are available on Google for wholesale as well.