Switching Regulator - Part 3

Buck Converter:

Simple Circuit Diagram:

1. VOUT < Vin
2. Efficiency > 90%
3. Power MOSFET may be internal or External for PWM controller

Detailed circuit Diagram:

1. Adding Large C across the load to control ripple.
2. Adding a inductor,to prevent the huge current spike
3. Adding Free wheeling diode, the switch can open and the inductor current can continue to flow.

Discontinuous operation:

1. Occurs for light loads, or low operating frequencies, where the inductor current eventually hits zero during the switch-open state
2. The diode opens to prevent backward current flow
3. The small capacitances of the MOSFET and diode, acting in parallel with each other as a net parasitic capacitance, interact with L to produce an oscillation
4. The output C is in series with the net parasitic capacitance, but C is so large that it can be ignored in the oscillation phenomenon

Typical Industry Step-down Converter:

Share your comments. Send your feedback to miycircuits@gmail.com