DC-DC converter with protection circuit for connection error

A DC-DC converter to convert a high voltage of a high voltage battery into a low voltage to charge a low voltage battery, the DC-DC converter comprising:

• a connecting unit connecting the high voltage battery and the low voltage battery;
• a converting unit configured to convert the high voltage which is supplied from the high voltage battery into the low voltage to charge the low voltage battery;
• and
• a protection circuit located between the connecting unit and the converting unit, and configured to be turned off turned off to shut off a current path between the high voltage battery and the low voltage, in response to an erroneous connection of the either one or both of the high voltage battery and the low voltage battery, wherein the protection circuit comprises
• a first protection element connected between a high voltage input line to which a positive electrode of the high voltage battery is connected and a low voltage output line to which a positive electrode of the low voltage battery is connected, and configured to be turned on, in response to a turn-on voltage or higher being applied to the high voltage input line, and
• a second protection element connected between the low voltage line and the low voltage output line to which a negative electrode of the high voltage battery and a negative electrode of the low voltage battery are commonly connected, and configured to be turned on, in response to the turn on voltage or higher being applied to the low voltage output line.