Power supply circuit and protocol control circuit thereof

A protocol control circuit for use in a power supply circuit, the power supply circuit comprising:

• a power converter circuit, which is configured to operably convert an input power to generate an output power at an output node;
• a path switch coupled between the output node and a bus node, the path switch being configured to operably control a power path between the output node and the bus node;
• and a temperature sensitive device, which is coupled to the bus node;
• wherein the protocol control circuit is configured to operably control the power supply circuit and the path switch, the protocol control circuit comprising:
• a shared pin coupled to the bus node via the temperature sensitive device, the shared pin being configured to operably transmit different signals having different functions under at least two different modes;
• and
• a signal determination circuit, which is configured to operably sense a voltage at the bus node via the shared pin under a power start-up mode, to determine whether to turn ON the path switch to conduct the power path, thereby determining whether or not to enter a power supply mode, wherein the path switch is OFF under the power start-up mode;
• and wherein the signal determination circuit is configured to operably receive a temperature signal generated by the temperature sensitive device via the shared pin under the power supply mode, to determine an ambient temperature.