| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply circuit capable of separating a first power supply part which supplies power to a sensor from a second power supply part which supplies power to a control circuit, and certainly suppressing fluctuation of output voltage due to temperature variation and current variation, and provide a water heater with the same. <P>SOLUTION: A power supply circuit includes: a constant voltage output part (linear regulator 1) which outputs constant voltage; a first power supply part (power supply 12 for an external IC and a sensor) which supplies the power output from the constant voltage output part to the sensor which detects a predetermined detection object; a second power supply part (power supply 13 for a microcomputer) which supplies the power output from the constant voltage output part to a control circuit which performs arithmetic processing based on a signal detected by the sensor; a power supply (capacitor 3) for backup connected to the second power supply part so as to supply power to the control circuit in power interruption of the constant voltage output part; and a MOS-FET 6 as backflow prevention means for preventing flow of current from the power supply for backup to the side of the constant voltage output part. <P>COPYRIGHT: (C)2013,JPO&INPIT |
