Linear voltage regulators vs. switching voltage regulators:
P = (Vin-Vout) X Iload
So for example if the input to the regulator is given from a 12V lead acid battery and the output voltage/current drawn is 5V/1A then the current drawn from the battery will also be 1 Amp so the power wasted in form of heat will be:
P = (12-5) X 1 = 7 Watts
Wasting 7 watts and that too through battery is pretty bad. And hence we need to think of an alternative. Well people have already thought about the alternative and that’s how switching regulators were born.
Switching regulators unlike the linear regulators regulate the output voltage by switching the storage elements (like capacitor or inductor) in different electrical configurations.
This is how a typical This is how a typical buck (step-down) regulator circuit looks like: looks like:
Fig. 1: Typical Circuit Diagram of Buck Regulator
Fig. 2: Image showing flow of current in Buck Regulator Circuit when switch is closed
When the switch is opened, the current again starts decreasing (i.e. changing) and hence again a voltage is developed in the inductor but this time, it adds to the source voltage instead of opposing it. The energy stored in the form of magnetic field is now utilized to supply the current to the load. If the switch is closed again before the inductor’s energy is completely used, then the voltage across the load always stays above zero.
Fig. 3: Image showing flow of current in Buck Regulator Circuit when switch is open
Here are the waveforms:
Fig. 4: Image showing input and output waveforms of Buck Regulator Circuit
Therefore, TON = 3 * TOFF
Filed Under: Circuit Design