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Up-to-date Knowledge is Power—Saves Energy, Time and Money

  • Author Tahmid
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  • Blog entry read time 2 min read
I am Syed Tahmid Mahbub, a Homemade Electronics Professional who has not done any course on electronics in any college or university. I am learning everyday from books, Internet, forums etc. and applying those knowledge in constructing practical circuits/simulation in my laboratory and also for Mahbub Micro Solutions, where I work as Chief Circuit Designer.

While doing some power electronics based projects, I was in need of drivers for MOSFET/IGBT. Earlier I thought that the output of PIC 12F/16F/18F series microcontroller is 2.5V (at 50% duty cycle) as shown by multimeter but afterwards I came to know, with great relief, that actually it is 5V but the meter shows the average value (learnt from FvM). So, here I needed drivers not with 2.5V compatible inputs but with 5V input capacity, so that they could be used with above mentioned microcontrollers. But while working with dsPIC33F series, I was faced with problem as the output of these microcontrollers is 3.3V (max 3.6V) only. So, to use these microcontrollers for driving POWER MOSFETs/IGBTs, I again required drivers with input capacity of minimum 3V.

But, in my country, for high frequency high-low side driving, only IR2110 and IR2113 are available. TLP250 is also available but it has a frequency limit of 20kHz only. Plus, it is only a low-side driver. Moreover, locally available Chinese origin IR series drivers (many of which are fake) are of poor quality and cannot be used with dsPIC33F series as operation is not recommended below 5v input.

So, I have collected costly NCP5181 manufactured by ON Semiconductor for dsPIC33F and L6385E manufactured by STMicroelectronics for use with PIC 16F/18F series.

With great satisfaction, I used these drivers for my test circuits – Linear Sine Wave Inverter (16kHz frequency and 128 steps sine table) with dsPIC33F (dsPIC33F is used as accurate output feedback is very difficult, if not impossible, to implement with PIC 16F/18F series at a reasonably higher frequency with large number of steps) and SMPS Sine Wave Inverter with PIC16F690 (16kHz frequency and 32 steps sine table) or dsPIC33F (64kHz freq and 128 steps). Here 16F series PIC Micro is used as input side feedback is done by the SG3525 IC that keeps the high voltage DC bus regulated. The dsPIC is used, since with 16F690 I’m limited to 8-bit (10-bit duty cycle with “decimal place”, but 8-bit time base) PWM; so dsPIC allows operation at higher frequency with larger number of steps.

But the irony is that, after few days, when I was going through the ST Microelectronics website, I came across a MOSFET Driver, L6391/L6392, which can be used for both dsPIC33F and PIC 16F/18F Series micros and is much cheaper than NCP5181.

If I would have the knowledge about this L6391/L6392 drivers earlier, I could use this in all my circuits instead of using 2 types of drivers. Cost would also be minimized.

So, up-to-date knowledge in all technical aspects is essential for planning and executing any type of useful product in electronics, especially in Power Electronics based products.


Hello Tahmid
BTW : for high frequency mosfet driving you can use a simple ferrite transformer as a driver.
Best Wishes
Yes. But I can't use that for sine wave PWM, where duty cycle swings between 0 and 100% (100% included). This would cause the transformer to saturate.
Yes i'm agree with you . but if the meesage signal of your PWM is a dc signal you can do it simply .
Good luck
Can you elaborate on what you mean by:

but if the meesage signal of your PWM is a dc signal you can do it simply.
Again Hi
Yes , but before that , tell me , do you know any thing about spectrum of PWM and SPWM ?
Is it regarding frequency spectrum? Modulating frequency and Carrier frequency? Please elaborate on what you mean by:
but if the meesage signal of your PWM is a dc signal you can do it simply. I am interested to know, as I never came across this sort of terminology(meesage signal of PWM).
Hi again Dear Tahmid
See my recent blogs , please , you'll find your answer on them .
Best Wishes
That was nice to read,...Though I have studies electronics, I still don't know how to design..I want to build my own circuits, how to go about it, where to start..
Hi Tahmid,
Nice to see a selfmade expert by practical way congratulations, I dont know theory much but the practice made me who i am today. Did you ever try using 6N137 for isolating the H-Bridge and to drive fet using some circuit.
Regards ani
I had used it to isolate the driving circuit from the MOSFET drive voltage source, which was an isolated power supply.

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