power supply module 504 generates an output voltage vo 2 u2033 and the output voltage vo 1 u2033 is higher than the output voltage vo 1 u2033 accordingly when the n type field effect transistor q 1 u2033 is turned on an output current io 2 u2033 may be divided from the output current io 1 u2033 of the main power supply module 502 and the output current io 2 u2033 may replace an output current io 3 u2033 generated by the auxiliary power supply module 504 a purpose of the detecting circuit 5086 is to detect the power outputted from the main power supply module 502 to selectively output the control signal vd u2033 outputted from the driving circuit 5082 to the first switching element 506 which is a bidirectional switch the power allocating apparatus 500 comprises a main power supply module 502 an auxiliary power supply module 504 a first switching element 506 a controlling device 508 and a second switching element 510 wherein the main power supply module 502 is coupled to a main power loading 512 and the auxiliary power supply module 504 is coupled to an auxiliary power loading 514 the second switching element 510 is an unidirectional switch and coupled between an output terminal n 1 u2033 of the auxiliary power supply module 504 and a terminal n 2 u2033 furthermore the timing of the control voltage vd u2033 can be adjusted through the on off operation of the controlling device 5082 in.