Ultra-low power switch slashes standby power

February 10, 2017 // By Nick Flaherty
Researchers at the University of Bristol have developed an ultra-low power switch that operates from a few picowatts, allowing sensors to save power and cut standby power to zero.

Dr Bernard Stark and colleagues in the Bristol Electrical Energy Management Research Group developed the voltage detector chip that requires only a few picowatts to activate other circuits. The research group are providing samples of their chip to companies to use, which will enable engineers to design sensors that continuously listen, without using power from a battery or mains.

The result is smaller batteries, or a battery life that is extended, in some cases by years. The voltage detector can also eliminate standby power, for example the team have demonstrated a TV with no continuous draw of power during standby, by using a voltage detector that is powered up at a distance, directly from the infrared signal of a standard TV controller.

The patent pending UB20M voltage detector allows circuit designers to develop circuits that perform continuous monitoring without using battery power, and to implement wireless wake-up with zero receiver power. The chip is a sensor-driven circuit that requires no power supply, instead it uses a fraction of the power contained in the output signal of the sensor. The researchers used the chip in a TV system with zero standby power. This uses the photodetectors from the infrared remote control to provide the power for the switch.

“The ultra-low power UB20M voltage detector provides sensing that is continuous and free," said Dr Stark, Reader in Electrical & Electronic Engineering in the Department of Electrical & Electronic Engineering. "This is because it is able to respond to minute quantities of power from unpowered sensors. No battery or other power is needed for the device to stay alive and listening, and battery maintenance is therefore reduced or not needed.  We are now actively seeking commercial partners to use the voltage detector chip in their product, and would welcome companies to get in touch."

The detector uses five picojoules of energy and only around half a volt which can be delivered directly from a sensor such as a photodetector, making listening