Feb 18, 2020 08:00:00

How has the power supply of computers and home appliances evolved?

When we usually use smartphones and home appliances, we don't really care about power. However, the power supply installed in products that use electricity such as smartphones and computers has undergone extraordinary technological development so far, and it has made great progress as well as CPU and memory, it is a former programmer of Google One

Ken Shirriff talks.

A Half Century Ago, Better Transistors and Switching Regulators Revolutionized the Design of Computer Power Supplies-IEEE Spectrum
https://spectrum.ieee.org/computing/hardware/a-half-century-ago-better-transistors-and-switching-regulators-revolutionized-the-design-of-computer-power-supplies

There are two types of electricity: direct current (DC), which has a constant flowing direction and magnitude, and alternating current (AC), whose magnitude and sign change periodically.When using home appliances, the AC power supplied from an outlet is converted to DC power. doing.

Devices that convert AC power into DC power so that computers and home appliances can use electricity are called “ DC stabilized power supplies ”. Depending on the method of conversion and stabilization, a linear power supply and a switching power supply are used. Method. The linear power supply uses a transformer to transform a high-voltage AC power supply into a low-voltage AC power supply, and then converts it to a low-voltage DC power supply with a linear regulator . Although it is difficult to reduce the size and the energy loss in the linear regulator is severe, it is a method that has been in existence for a long time and can be manufactured at low cost and has a simple structure.

On the other hand, a switching power supply converts an AC power supply to a high frequency through a

transistor that repeatedly turns on and off at high speed, and then converts it to a DC power supply. Switching power supplies generate high-frequency electricity, which enables flexible operation of voltage, and high energy efficiency without the need for linear regulators. The concept of switching power supplies was first born in the 1930s, but switching power supplies were more complex than linear power supplies and required high-quality components, making them difficult to design.

The earliest switching power supplies were used in teletype terminals REC-30 and IBM 704 , but even in the era when vacuum tubes were used, switching power supplies were technically linear enough to be used only in very limited ways. Power supply was inferior. In the 1960s, switching power supplies began to be adopted by NASA and other aerospace industries who were willing to pay attention to the small size and high energy efficiency of switching power supplies. Switching power supplies have been reduced in size and power have been saved enough to be adopted for the Telstar satellite and the Minute Man missile, which are the first satellites to successfully transmit TV images.

As a result of the research and development of switching power supplies by the aerospace industry, switching power supplies began to be used in general commercial power supplies in the late 1960s.

Tektronix has developed an oscilloscope-based mains and battery-operated power supply, and RO Associates has developed the first 20kHz switching power supply, with commercial success. In Japan, the switching power supply was developed by TDK 's Nippon Electronic Memory Industry in 1970.

In the 1970s, the adoption of switching power supplies began to advance in the computer industry. The computer industry giants such as IBM and HP , including DEC 's PDP-11 / 20 , have also adopted switching power supplies, and switching power supplies have begun to spread as color televisions have adopted them.

Robert Boschert revolutionized the switching power supply. Boschert has succeeded in simplifying the structure of the switching power supply, and in terms of cost, the switching power supply can compete with the linear power supply. Also, at that time, the performance of the transistor was dramatically improved, and in some cases the transistor one and a half years ago was completely out of date. The simplification of the design, the higher performance of the transistors, and the lower price have led to the establishment of the power supply as a switching power supply, so that it can be used in F-14 fighters.

It is said that the computer switching power supply was completed to its present form when the IBM PC appeared in 1981. The power supply of the IBM PC has an IC chip controller, and it incorporates roughly twice the number of parts of the power supply of Apple II announced four years ago of the IBM PC, much higher performance It was that.

by Laura Blankenship

At present, power supplies for computers generally conform to the ATX standard formulated by Intel, and have a power supply stabilization circuit for CPU called VRM . The US government is also promoting the use of the Energy Star program and 80 PLUS certification in response to rising concerns about increased computer energy consumption. Shirriff says that many of today's power supplies can communicate with systems using digital circuits, and software knowledge is also important in the power supply field.