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I’ve already shown how to drive an N-channel MOSFET (or even an IGBT) in both high-side and low-side configurations in a multitude of ways. I’ve also explained the principles of driving the MOSFETs in these configurations. The dedicated drivers I’ve shown so far are the TC427 and IR2110. Some people have requested me to write up on MOSFET drive using the very popular TLP250. And I’ll explain that here. The TLP250, like any driver, has an input stage, an output stage and a power supply connection. What’s special about the TLP250 is that the TLP250 is an optically isolated driver, meaning that the input and output are “optically isolated”. The isolation is optical – the input stage is an LED and the receiving output stage is light sensitive (think “photodetector”). Before delving any further, let’s look at the pin configuration and the truth table. Fig. 1 - TLP250 Pin Configuration Fig. 2 - TLP250 Truth Table Fig. 1 clearly shows the input LED side and the receiving photodetector as well...

We all know what a motor is and what it does. The simplest way to run a motor is to just connect it to a power source. For a DC motor, that would mean, just connecting the motor to the DC voltage that the motor was rated for (or less). But, can you control the speed? Yes. The simplest method is to control the speed of the motor by controlling the voltage the motor runs off. Imagine we have a 12V motor. If you run it off 12V, you get maximum speed (you can get more at higher voltage, but let's not go over rated specifications!). So, simple logic dictates that as we decrease the voltage to the motor, the speed must decrease. You can use a simple LM317 regulator to adjust the voltage to the motor and thus the speed. But, this method of speed control has one huge disadvantage - inefficiency when using a linear regulator (and you may find the motor not running at all at lower voltages). Let's talk about the inefficiency. If we use a linear regulator to give 6V output from 12V input,...