In buck converters the output voltage is always less than the input voltage. The basic circuit of buck converter is shown in figure. The operation of this circuit can be divided into two modes. In mode transistor Q is turned on at t=0 to t=t this time interval from 0 to t1 is ton. In mode 2 transistor is turned off at t=t to ti=t2 and this time interval t2- t1is Toff.