The most common way of dealing with such circumstances is to use uninterruptible power supplies (UPSs) to cover these brief downtimes, thus ensuring high reliability, continuous operation of the system. Similarly, many of today’s emergency and standby systems are used to provide backup power for building systems to provide assurance that safety systems and critical equipment can maintain their operation during a power outage—whatever the root cause.
Obvious examples can be readily found in the ubiquitous handheld electronic devices used in our everyday lives. Because dependability is paramount, handhelds are carefully engineered with lightweight power sources for reliable use under normal conditions. But no amount of careful engineering can prevent the mistreatment they will undergo at the hands of people. For example, what happens when a factory worker drops a handheld portable scanning device, causing its battery to detach? Such events are electronically unpredictable and important data stored in volatile memory would be lost without some form of safety net—namely some sort of short-term power holdup system that stores sufficient energy to supply standby power until the battery can be replaced or the data can be stored in permanent memory.
In automotive electronic systems there are many applications that require continuous power even when a car is parked (engine not running), such as remote keyless entry, security, and even personal infotainment systems. These systems usually incorporate navigation, GPS location, and eCall functionality. It is easy to understand why these systems have to remain on even when the car is not moving, since the GPS aspect of these systems must be always-on for emergency and security purposes. This is a necessary requirement so that rudimentary control can be activated by an external operator when necessitated.