Meeting power demands in modern day electronics is quite a challenge and there are times where we will not be able to supply sufficient voltage for our circuits. In that case we need to go for DC to DC boost converter circuits like these to step up the incoming voltage to a certain usable level. These kinds of step up converter circuits will be useful in Solar powered projects, Lighting systems, Battery powered projects and so.
In order to understand the above circuit we need to understand this chip. MT3608 is a 6 pin DC to DC step up converter used to boost the incoming supplied voltage. Also this chip switches the load at about 1.2Mhz and only uses very few minimal external components to operate. Also it is equipped with under-voltage lockout circuit, current limiting and thermal overload protection just in case output tries to draw more current than its limit. This chip takes input voltage from 2 to 24V and Output voltage up to 28v and capable of delivering maximum current of about 4A. Checkout the Datasheet of MT3608 here for info about this chip.
WORKING OF 5V TO 12V BOOST CONVERTER CIRCUIT:
In MT3608 Chip, internally there is a power MOSFET that have its Drain pin connected to the inductor via SW pin and Source pin of Inductor is connected to ground. A typical MOSFET switch configuration. As soon as we power up the circuit the internal oscillator of MT3608 start to turn the MOSFET ON and OFF at a frequency of 1.2MHZ. When the MOSFET is in its ON state, the current coming through the Inductor passes through MOSFET to ground. Therefore when current passes through an Inductor, a magnetic field generates in it.
After a certain point internal MOSFET will be turned OFF. This point is decided by the voltage at the feedback pin provided by the voltage divider R2 and R1. The output voltage is governed by the formula
Vout = Vref x ( 1 + R1 / R2 )
where Vref is 0.6v.
After the MOSFET is turned off, the magnetic field of the Inductor turns in to voltage spike and it goes through the Schottky diode. Hence this voltage spike will be exhibited as output in the circuit. As there is a capacitor in the output, it charges in every cycle of oscillation and keeps the voltage constant. In this voltage booster circuit components are used to boost 5v to 12v. Above all for MT3608 to start working, the EN pin should be tied to high. If you want to turn on and off the output with an external circuit you can use this pin. This circuit is capable of delivering 2A current to the Load.
ADJUSTABLE OUTPUT VOLTAGE:
This circuit is similar to the above except output voltage in the circuit can be adjusted. As I already mentioned that output voltage is set by means of Voltage fed into the FB pin of MT3608. Here I have replaced the resistor R1 with Potentiometer PR1. As the resistance of POT changes the voltage in to the FB pin changes which in turn will change the output voltage accordingly.
Hope this Boost converter circuit will come in handy for your next projects. Feel free to post your comments, Feedbacks and questions regarding these circuits below. Bookmark our website and check it out weekly. New Projects / Circuits will be published on weekly basis.
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