Intrinsically safe energy harvester for powering multi-sensor
An electrical circuit for protecting an electronic device, and a method of operating the electric circuit, can involves the use of a protection circuit that includes a group of diodes and one or more field effect transistors, along with an energy storage device associated with the electronic device. The field effect transistors are electrically connected to the group of diodes, and reference voltage associated with the protection circuit is tunable to trigger the protection circuit at a threshold voltage, which when triggered activates the field effect transistor(s) to protect the energy storage device from an over voltage condition or an over charging condition until the over voltage condition or the overcharging condition is no longer present.
1 . A shunt protection circuit, comprising:
a plurality of Zener diodes electrically connected in parallel and configured to shunt excess voltage above a predetermined threshold;
an energy storing device connected in parallel with the plurality of Zener diodes; and
a plurality of circuits situated between the plurality of Zener diodes and the energy storing device, each circuit comprising a metal-oxide semiconductor field effect transistor (MOSFET) and a shunt regulator with a reference voltage set to activate the shunt regulator at a predetermined threshold voltage, wherein the shunt regulator of each circuit conducts when the voltage across the plurality of Zener diodes reaches the predetermined threshold voltage, thereby causing the MOSFET of each circuit to conduct and thereby protect the energy storing device,
wherein the shunt protection circuit is deployable in Zone 0/Class I Division 1 hazardous location (HAZLOC) areas.
2 . The shunt protection circuit of claim 1 wherein each shunt regulator maintains a low reverse leakage current in the order of tens of microamps when not triggered.
3 . The shunt protection circuit of claim 1 wherein an overall system leakage current is maintained below 10 microamps, thereby minimizing drainage of the energy storing device and meeting performance requirements of an end application.
4 . The electrical circuit of claim 1 , wherein each MOSFET comprises a P-Channel MOSFET.