State the type of switching regulator shown in FIGURE 2 and

State the type of switching regulator shown in FIGURE 2, and briefly explain its operation. b) In FIGURE 2, R_1 = 10 k Ohm, V_ref = 1.25 V and the duty cycle D is 30%. Determine: i) the required value of R_2 [select the nearest preferred value from the E24 series]. ii) the value of V_IN.

Solution

Linear Technology manufactures a broad line of high performance switching regulator ICs with both synchronous and non-synchronous internal switches. These switching voltage regulators offer typical input voltage capability from 2.25V up to 60V, switching frequencies up to 4MHz and high efficiency operation up to 96%. Also with Burst Mode operation, quiescent currents in the tens of micro-amps level can be attained. This combination of features allows very small, low profile circuit implementations with minimum external components. Topologies include buck (step-down) switching regulators, boost (step-up) switching regulators, buck-boost switching regulator, inverting switching regulators, and flyback and isolated topology switching regulators.

Other features include adjustable or synchronizable switching frequency, small size, low external component count and more.

To understand how these black boxes work lets take a look at a traditional linear regulator at right. As we see in the diagram, the linear regulator is really nothing more than a variable resistor. The resistance of the regulator varies in accordance with the load resulting in a constant output voltage

b.

Although most power supplies used in amateur shacks are of the linear regulator type, an increasing number of switching power supplies have become available to the amateur. For most amateurs the switching regulator is still somewhat of a mystery. One might wonder why we even bother with these power supplies, when the existing linear types work just fine. The primary advantage of a switching regulator is very high efficiency, a lot less heat and smaller size.
	To understand how these black boxes work lets take a look at a traditional linear regulator at right. As we see in the diagram, the linear regulator is really nothing more than a variable resistor. The resistance of the regulator varies in accordance with the load resulting in a constant output voltage	b.