A power management module electrically coupled between an AC/DC switching power supply and an electronic apparatus comprises a memory device, voltage and current detecting units, a writing unit, and an alarm signal generation unit. The memory device generates an output data to the electronic apparatus. The voltage and current detecting units detect voltages and currents of the output terminals of the switching power supply, respectively. The writing unit writes a new input data and the voltage and current data to the memory. The alarm signal generation unit generates an alarm signal to the electronic apparatus according to the data stored in the memory device and according to the operation condition of the switching power supply.