Power supply apparatus and method applied to cruise system

A power supply apparatus and method applied to a cruise system are used for generating a power supply signal responding to a mode selection signal. The power supply apparatus includes a reference voltage circuit, a high-precision mode driving circuit, a low-power mode driving circuit, and a control circuit. The reference voltage circuit generates a reference voltage signal. The control circuit chooses to operate in a high precision mode or a low power mode according to the mode selection signal. When the operation is carried out in a high precision mode, the control circuit generates a power supply signal according to a first driving signal generated by the high-precision mode driving circuit. When the operation is carried out in a low power mode, the control circuit generates a power supply signal according to a second driving signal generated by the low-power mode driving circuit. The control circuit decides whether to start the reference voltage circuit according to the second driving signal. 种应用于巡航系统的电源供应