BATTERY PACK

A battery pack includes a battery including at least one battery cell, a DC/DC converter configured to generate first control power from battery power of the battery, an OR circuit configured to output control power having a higher voltage level from among second control power received from an external power supply device through a first external terminal and the first control power, a power supply circuit configured to generate driving power by using the control power received from the OR circuit, a control circuit driven by the driving power, and a first switch connected between an output terminal of the DC/DC converter and a second external terminal and controlled by the control circuit; the battery pack supplies the external control circuit with the control power generated by the DC/DC converter in the event of a power failure.