Abstract:

A low power loss flow-meter is designed based on the MSP430F149 to cope with the high electricity expense caused by the lack of the external power supply or by the use of wires.Both hardware and software designs are presented.The system power source adopts two levels conversion:a logical judgment selecting circuit is designed for the primary conversion,as the pressure drop DC/DC and LDO have their respective advantages in transfer efficiency under different conditions;in the secondary conversion,LDO is used to lower the power line voltage of the simulation part so as to save the power loss.The system temperature and the pressure compensation modules adopt the intermittent sampling pattern,which cuts off constant current supplies in the sampling gaps from the upper voltage end using SPDT (single pool double throw),thus reducing the system power loss.The system mean current reduces to 470 μA,which meets the battery power supply design requirement.

Key words: flow meter;MSP430;low power