Electel Blogspot

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

The PIC32MX250F128B has a myriad of peripheral features that makes this cheap little 28-pin 32-bit microcontroller extremely powerful. However, it does lack a digital-to-analog converter (DAC). A simple approach to digital-to-analog conversion is to use one of the PWM channels and then to use an RC low-pass filter at the output. However, there is another neat little feature of the device that can be exploited or rather utilized to obtain a rather crude DAC – the analog comparator module. Rather, the analog comparator reference module. The PIC32MX250F128B contains an internal voltage reference module that was created to be used as a reference voltage for the internal analog comparator module. However, it does allow you to output this reference voltage to an output pin. Analog voltage output with digital control? Sounds like a DAC. The voltage reference module is built off of a 16-tap resistor ladder network with two selectable ranges – from 0 to 0.67 CVREF or from 0.25 to 0.75 CVREF. CV