Intrinsic Safe Power for Special Wireless Sensor Network Node

Wireless sensor networks may be used in the explosion environment, such as underground tunnel in coal mine. In order to assure sensor node work normally, the power of a sensor node must be intrinsic safe. The intrinsic safe power of a sensor node, which consists of power supply module and intrinsic safe protection module, is developed. The power supply mainly consists of current-mode controller chip LTC1871 which assures a stable output voltage of a sensor node. The intrinsic safe protection consists of a dual-stage electric current monitor chip and a voltage regulator tube, which are combined with an over-voltage protection that was integrated in LTC1871 to make up intrinsic safe protection circuit of double over-voltage and over-current protection. Theory analysis and simulation test on discharge process of intrinsic safe power are described. The results display that the discharge energy is nonlinear proportion to the current, increases with the current increasing, and the maximum discharge energy is less than 0.02 mJ; the discharge power is linear proportion to the current, increases with the current increasing, and the maximum discharge power is less than 60 W, which meets the intrinsic safe standard, therefore the power of the sensor node is intrinsic safe.