Voltage selector

A voltage selector comprising:

• a first input terminal configured to receive a first input voltage;
• a second input terminal configured to receive a second input voltage;
• an output terminal configured to output an output voltage;
• a main select circuit comprising:
• a select unit comprising a first transistor coupled between the first input terminal and the output terminal, and a second transistor coupled between the second input terminal and the output terminal, wherein the first transistor is configured to be turned on when the first input voltage is higher than the second input voltage, and the second transistor is configured to be turned on when the second input voltage is higher than the first input voltage;
• and
• an auxiliary unit configured to be controlled by a reference voltage to be activated to conduct at least one of a first electrical path between the first input terminal and the output terminal or a second electrical path between the second input terminal and the output terminal to pull up the output voltage when the first input voltage equals to the second input voltage;
• and
• a reference circuit comprising:
• a pull down unit configured to pull down the reference voltage to activate the auxiliary unit to conduct the first electrical path or the second electrical path when the first input voltage equals to the second input voltage and the output voltage is lower than the first input voltage by a threshold voltage.