Pull-up voltage detection circuit and pull-up voltage detection method

A pull-up voltage detection circuit, located in an integrated circuit and for use in a serial bus, wherein the serial bus includes a communication signal, wherein during at least one communication interval, the communication signal is toggled via open drain scheme based on a pull-up voltage for communicating on the serial bus, wherein the pull-up voltage is coupled to the serial bus external to the integrated circuit, wherein the pull-up voltage has plural pull-up voltage levels according to a specification compliant to the serial bus;

• the pull-up voltage detection circuit comprising:
• at least one comparator circuit, which is configured to operably compare the communication signal or a divided voltage thereof with at least one reference voltage in a detection procedure, so as to generate at least one comparison result;
• and
• a selector circuit, which is configured to operably select one of at least two predetermined voltages according to the at least one comparison result, wherein the selected predetermined voltage serves as a logic threshold voltage corresponding to the pull-up voltage;
• wherein in the at least communication interval, a logic state of the communication signal is determined by comparing the communication signal and the logic threshold voltage for communicating on the serial bus.