Stabilized DC voltage is required to run electric
appliances stably. That is why stabilized DC power supply exists.
Currently, mode for stabilized DC power supply roughly classified
into switching mode and series mode.
<< Switching mode >>
Basic block diagram of switching mode is shown in Figure 1.3 below.
Figure 1.3 Basic block diagram of switching
In switching mode, rectified voltage is switched (turned ON and
OFF) at high speed to be converted to alternate voltage with high
frequency (pulse). This alternate voltage is rectified again. By
high frequency switching, transformer can be smaller to contribute
to compact equipment. Also, heat buildup becomes low to bring high
efficiency. However, switching increases noises.
<< Series mode >>
Basic block diagram of series system is shown in figure 1.4 below.
Figure 1.4 Basic block diagram of series mode
In series mode, output voltage is stabilized by series regulator
as input voltage changes. Noise and ripple voltage is small, but
efficiency is poor to bring large and heavy transformer without
high frequency conversion.
<< Comparison between switching and series mode is
shown below in Table 1.1. >>
Table 1.1 Comparison between
switching and series system