Patent attributes
One or more embodiments relate to a switch-mode power supply control circuit that can be used to provide power to regular single phase or three phase energy meter, while also offering a simple low cost method to detect a magnetic tampering event that usually occurs on energy meter. In one example, the switch-mode power supply for the energy meter is a flyback type switch mode power supply comprising a power switch, a switching controller, and a slew rate based magnetic field detection circuit which is configured to enable a magnetic tampering detection signal that can be communicated to the switching controller. Upon detection of a magnetic tampering event, the power supply and the supporting circuitry can raise the switching frequency of the power switch in order to provide more power to the output or cutoff power to the consumer's power outlet and even report the tampering event to the power station.