Low-power electronics

Low-power electronics are electronics that have been designed to use less electric power, e.g. notebook processors.

The earliest attempts to reduce the amount of power required by an electronic device were related to the development of the wristwatch. Electronic watches require electricity as a power source, and some mechanical movements and hybrid electronic-mechanical movements also require electricity. Usually the electricity is provided by a replaceable battery. The first use of electrical power in watches was as a substitute for the mainspring, to remove the need for winding. The first electrically powered watch, the Hamilton Electric 500, was released in 1957 by the Hamilton Watch Company of Lancaster, Pennsylvania.

Watch batteries (strictly speaking cells, as a battery is composed of multiple cells) are specially designed for their purpose. They are very small and provide tiny amounts of power continuously for very long periods (several years or more). In some cases, replacing the battery requires a trip to a watch-repair shop or watch dealer. Rechargeable batteries are used in some solar-powered watches.

The first digital electronic watch, a Pulsar LED prototype in 1970. Digital LED watches were very expensive and out of reach to the common consumer until 1975, when Texas Instruments started to mass-produce LED watches inside a plastic case.

Most watches with LED displays required that the user press a button to see the time displayed for a few seconds, because LEDs used so much power that they could not be kept operating continuously. Watches with LED displays were popular for a few years, but soon the LED displays were superseded by liquid crystal displays (LCDs), which used less battery power and were much more convenient in use, with the display always visible and no need to push a button before seeing the time. Only in darkness you had to press a button to light the display with a tiny light bulb, later illuminating LEDs.

As of 2013, processors specifically designed for wristwatches are the lowest-power processors manufactured today—often 4-bit, 32 kHz processors.

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