A tutorial on switching-mode power supply design by Jerrold Foutz

As explained in the introduction, a power supply is a buffer circuit that is placed between an incompatible source and load in order to make them compatible. In this section we explore some simple dissipative circuits that can be placed between a 12 Vdc battery and a 5 Vdc load to make them compatible. The buffer circuits are simple in that we will restrict the parts to one each or less of the following parts: variable resistor, breakdown diode, switch, diode, single winding inductor, and capacitor.

For the dissipative topologies we will only use the variable resistor and the breakdown diode. The other parts will be used in the next section on switching topologies.

We will be concerned only with the power conversion part of the circuit, not the control. We will assume that the circuits are open loop and the output voltage is controlled manually by the value of a variable resistor or the duty cycle of a switch.

Although simple from a parts basis, the circuits we will explore with these parts are not necessarily simple from an analytical viewpoint. Some of the switching topologies will contain right-half-plane zeroes, an interesting topic that will be discussed later in this tutorial.