MIT Engineers Create Power Supply That Efficiently Sips Energy

A new type of power supply has been created by researchers from MIT which sips energy by utilizing packets of energy rather than a voltage stream. Power supplies generally provide steady voltage which is highly inefficient when it comes to small devices that do not require to be constantly fed power and turned on.

“Typically, converters have a quiescent power, which is the power that they consume even when they’re not providing any current to the load,So, for example, if the quiescent power is a microamp, then even if the load pulls only a nanoamp, it’s still going to consume a microamp of current. My converter is something that can maintain efficiency over a wide range of currents.” said Arun Paidimarri, formerly of the MIT’s Microsystems Technological Laboratories.

The power supply sends power only as needed and reverts to a quiescent state otherwise. This type of power supply is useful with the growing Internet-of-Things devices as it can take a 1.2 to 3.3V input and step it down to 0.7 to 0.9V and only use the amount needed which includes the sensing and the calculation required itself. The control circuitry for the switches includes a circuit that measures the output voltage of the converter. If the output voltage is below the 0.9V threshold, the controllers throw a switch and release a packet of energy. Then they perform another measurement and if necessary, another packet is released. For simple local circuits, the controller might release up to a couple of hundred of packets per second but if the controller is feeding a radio, it can increase the packet released up to a million per second.

The method however, lowers the converter’s efficiency, hence the researchers have outfitted the divider by a block of additional circuit elements which control and limit access to the divider only for the required measurement. The result is a 50 percent reduction in quiescent power over even the best previously reported experimental low-power, step-down converter and a 10x expansion of the current-handling range. The application is wide and the results also open up the possibility of new types of energy harvesting sources due to its efficiency, including body-powered electronics.