MOSFETS FOR LIFTING HEAVY LOADS

This post helps you to understand when to use mosfet’s instead BJT’s.

Transistors are one of the best invention that changed the human life, computer uses transistors to work and every sequential logic boards also.

But we are interested in using transistors for switching! Heavy loads.

Basic functioning of transistor is Switching ON and OFFelectronically, this is useful to turn devices or circuit on or off.

So this transistors best variants are BJT’s and MOSFET’s, we going to discuss about MOSFET’s today.

MOSFET stands for "METAL OXIDE SEMICONDUCTOR FEILD EFFECT TRANSISTOR" which is also like bjt's but can be used to switch heavy loads with VOLTAGE control, unlike bjt's where you have to control using current and power loss is greater in BJT.

Mosfet’s can reduce the power dissipation upto 20%, also they can be controlled with voltage unlike current control it is easy.

Mosfet’s are 2 types 1) ENHANCEMENT TYPE    2) DEPLETION TYPE

But one downside is MOSFET gate voltages are different for different mosfet’s, switching applications requires some different characteristics like:

1.low gate voltage(LOGIC level is preferred )

2.low on time delay

3.less Rds value Today we going to discuss the IRFZ44n mosfet which is N-channel ENHANCEMENT TYPE mosfet, which is most preferred mosfet for uC’s. Advantages of this particular one:

1.  This one can be switched on with 4V logic hence can be used with Arduino variants.

2.  Have max drain current capacity of Id = 49A

3.  This one have less Rds(drain to source resistance) Rds< 22mohms

4.  Which also have good switching speed 12ns

With all advantages comes with some disadvantages too, the biggest one is mosfet’s are sensitive to static charges they are kryptonite of mosfet’s , and the next big disadvantage is mosfet have parasitic capacitance which sometimes are real need to take care for avoiding problems. That’s why we need mosfet drivers, watch this video for why we need mosfet drivers for 

https://www.youtube.com/watch?v=8swJ_Bnsgl4

Hence that being said the perfect mosfet with transistor driver for the microcontrollers to switch heavy loads, if you are using 3.3v logic u-controllers than you have to Bjt to switch the mosfet to switch.

So I’m here using a 2n3904 as bjt to switch mosfet IRFZ44N.

Here is the recommended circuit for any Microcontroller to use:

[NOTE: this particular mosfet have some capacitance in the gate hence it can turn on by just touch of human Use “10Kohm” resister to pull it down to GND.]