Figure 1 shows a typical low-power system operating with a Li-Ion
battery. The battery’s usable output varies from 3 V to 4.2V, while
the ICs require 0.8 V, 1.8 V, 2.5 V, and 2.8 V. A simple way to
reduce the battery voltage to a lower dc voltage is to use a lowdropout
regulator1 (LDO). Unfortunately, power not delivered to
the load is lost as heat, making LDOs inefficient when VIN is much
greater than VOUT. A popular alternative, the switching converter,
alternately stores energy in an inductor’s magnetic field, and
releases the energy to the load at a different voltage. Its reduced
losses make it a better choice for high efficiency. Buck, or step-down