DC TO DC buck converter
This is a DC to DC Buck converter working principle. We often use it as a step down DC to DC converter circuit. Because it is a switching mode power supply.
It works by switching on and off. So it can get a much higher power efficiency than a linear power supply. Which it steps down voltage from a high input to a low voltage output. While it will step up output current to load. So it lets save power source.
Figure 1 Buck converter working principle
Figure 1 is basic buck converter circuit. It powers a certain output voltage. Other converter systems may call that a step down.
First, the Uin charges into capacitor until full. The its voltage is same as the power supply input.
Next, switch closed into the circuit. Therefore the positive voltage to drop across the coil L.
The current flow through coil to increase up in linear rate. While there is energy stored in the coil.
Then, the S open up. So, the current of L flow to the output capacitor.
And it flows through Diode (D). It makes the voltage drop across the coil L in backward (negative).
And, the current through the coil reduces in linear. The energy stored at the output capacitor.
When the switch (S) connected to the circuit again. The system started working the new one. To be able to supply the load continuously.
Figure 2 Three types of current mode
In normal principle, the electricity flows in 3 modes. As shown in Figure 2.
- Continuous mode (CM): When switch is closed. Then, the current is continuously flowing in coil. See Figure 2A
- Discontinuous mode (DM): But if we control times to switch on-off .
- CM/DM boundary: This mode, the switch turn-on immediately, if current of coil drop to zero.
