Power management device and method of operating the same

A power management device comprising:

• a converter connected to an output node of an energy source, and configured to convert a voltage across the output node of the energy source, based on a first control signal, to output a final output voltage;
• a sampling circuit including a sampling node connected to the output node of the energy source, the sampling node being for measuring a sampling voltage related to an open circuit voltage of the energy source, based on a second control signal;
• a maximum power point tracking (MPPT) management circuit configured to generate the first control signal, based on the second control signal, the sampling voltage, and the voltage across the output node of the energy source;
• and
• an MPPT control circuit configured to control a voltage level of the sampling voltage to be changed within a first threshold voltage range by applying a current to the sampling node, based on the second control signal and the sampling voltage.