An electronic apparatus includes a converting circuit and a first control circuit. The converting circuit converts an input voltage to an output voltage. The first control circuit compares a feedback signal representing the output voltage with a target voltage to generate an error voltage. When the electronic apparatus is on a starting-up status and the error voltage is not greater than a threshold voltage, the first control circuit outputs a first driving signal to drive the converting circuit according to the error voltage. When the electronic apparatus is on a starting-up status and the error voltage is greater than the threshold voltage, the first control circuit stops outputting the first driving signal. A frequency of the first driving signal is determined according to the error voltage.