DIY Buck Converter || How to step down DC voltage efficiently

let's say you just got a new awesome electronic module that requires five folds in order to work but all you have is a 12-volt power source the easiest solution would be to use a lm7805 voltage regulator with an input and output capacitor to step down 12 volts to 5 volts but if we measure the input and output power we can see that the efficiency is quite low and gets even worse with higher input voltages because the regulator is basically a variable resistor that converts the excess power into heats which is not recommended when the power source is a battery to reach a higher efficiency though we can use the so-called buck converter this one is very small has an adjustable output voltage doesn't cost much and also reaches a decent efficiency but how do these converters work and can we even build one by ourselves let's find it out a buck converter is a kind of SMPS or switched-mode power supply as an example I will use naught we know Nano which can switch its output pins on and off rapidly whippets pwm function here I use the value 127 which creates a square wave will be due disciple of 50% if I now measure the voltage with my multimeter it already tells me that we successfully step-down or 5 volts to 2.5 volts because it measures the average and for undemanding components like LEDs this method already does a trick but in order to control higher voltages and bigger current draws we need to upgrade the switch to a p-channel MOSFETs by hooking up 12 volts to source a 10 kilo ohm pull-up resistor between gate and source gate also to the PWM signal and going to the loads I condemn the small light bulb and by connecting a potentiometer to analog inputs and adjusting the coder pits I can also control the duty cycle and thus increase or decrease the average boot and brightness of the bulb but our switched voltage still has high voltage Peaks which will destroy sensible five-fold electronics so we have to get rid of them to do that I firstly added 100 micro Henry inductor in series to the loads this way the current cannot rise instantly because a part of the energy is stored in the electromagnetic field of the coil and once the switch opens the electromagnetic field collapses and should pump a current through the loads which it does do properly instead we get those massive voltage spikes at the switch which is not a surprise since there is no complete loop in which the current could flow and thousand electron access occurs that is why I added a Schottky diodes were below forward voltage to the circuits so that current can flow when the switch is open but the resulting current flow is still far away from a steady value to further improve that we need to increase the frequency of the PWM signal which is right now around 976 Hertz I simply change the prescaler in my sketch uploaded it and promptly got a frequency of sixty-two point five kilo Hertz with such a short off time the energy storage capacity of the inductor is now enough to smooth out the current flow quite a bit that is also the reason why switched mode power supplies usually use a high frequency in order to keep energy storage components small all that was left to do but my design was adding a 47 micro farad capacitor on the outputs to smooth out the voltage and the buck converter was complete and reach the efficiency year of 67 percent with my light bulb at 5 volts which is not terrible but once I change this big load to something smaller like a 50 ohm resistor the output voltage jumped up to eight point five volts that means we need to use a voltage divider which provides a feedback voltage to control system in order to adjust the duty cycle and thus keep the output voltage steady no matter what load is attached and since this is getting a bit complicated let's keep things simple with this - 576 simple switch I see I have the 5 volt version that has it feedback resistors integrated and also only requires 4 additional parts to build up a complete buck converter the rule of thumb while recreating the schematic is to keep all the parts close together and creating fix order traces after only 10 minutes of soldering the circuit was complete works flawlessly and obviously reached a better efficiency year than my demonstration circuits and if you want to make your own power converter I can recommend the adjustable version of this IC there you can add your own feedback resistors or potentiometer to create an adjustable output voltage and with that being said you already know quite a bit about stepping down voltages efficiently with a buck converter I hope you liked it and learnt something new as well as always don't forget to Like share and subscribe consider supporting me through patreon so I can continue producing such videos stay creative and now we'll see you next time

Channel: GreatScott!

Views: 757,817

Rating: 4.9264302 out of 5

Keywords: buck, converter, efficient, efficiently, step, down, step down, dc, dc voltage, smaller, switched mode power supply, smps, switch, switching, LM2576, lm2576, simple switcher, mosfet, p channel, tutorial, how to, diy, make your own, coil, inductor, diode, arduino, easy, simple, greatscott!, greatscott, electronics

Id: m8rK9gU30v4

Length: 5min 32sec (332 seconds)

Published: Sun May 01 2016