Fan control circuit and fan control system

A fan control circuit, applied to a server, comprising:

• a fan controller connected with at least one fan connector, connected with a baseboard management controller via integrated circuit bus communication lines and outputting a baseboard management controller fan signal, wherein said fan controller is powered by a main power supply;
• and
• a baseboard status detection circuit connected with the baseboard management controller and the fan controller respectively, detecting a heartbeat signal of the baseboard management controller, and controlling an output of a fan pulse signal according to the heartbeat signal so as to control a fan connected with the fan controller to operate normally;
• wherein the baseboard status detection circuit comprises:
• a heartbeat signal detection circuit connected with an output terminal of the heartbeat signal of the baseboard management controller, detecting the heartbeat signal of the baseboard management controller and outputting a heartbeat status signal;
• and
• a logic control circuit connected with the heartbeat signal detection circuit, and controlling an output of pulse selection signal according to the heartbeat status signal;
• wherein the baseboard status detection circuit further comprises:
• a pulse generator generating a predetermined fan pulse signal for driving the fan to operate normally;
• and
• a pulse multiplexer connected with the logic control circuit, the pulse generator and the fan controller respectively, wherein the pulse multiplexer chooses to output the predetermined fan pulse signal to an output port of the pulse multiplexer when the pulse selection signal indicates a first selection status, and the pulse multiplexer chooses to output the baseboard management controller fan signal to the output port of the pulse multiplexer when the pulse selection signal indicates a second selection status.