Sinrace Power Supply Technology (Shenzhen) Co., Ltd.

The benefits provided by implementing switch mode operation are with respect to size, weight, and efficiency.

Size and weight - since the transformer and final filter(s) run at a high frequency (we are talking about 10 kHz to 1 MHz or more), they can be much smaller and lighter than the big bulky components needed for 50/60 Hz operation. Power density for SMPSs compared to LPSs may easily exceed 20:1.

Efficiency - since the switching devices are (ideally) fully on or fully off, there is relatively little power lost so that the efficiency can be much higher for SMPSs than for LPSs, especially near full load. Efficiencies can exceed 85% (compared to 50-60% for typical LPSs) with improvements being made continuously in this technology.
Since the advent of the laptop computer, cellular phone, and other portable devices, the importance of optimizing power utilization has increased dramatically. There are now many ICs for controlling and implementing SMPSs with relatively few external components. Maxim, Linear Technology, and Unitrode (now part of Texas Instruments) are just a few of the major manufacturers of controller ICs.