Voltage input circuit

A voltage input circuit, applied to a notebook computer, and comprising:

• a first voltage terminal, for receiving and outputting voltage;
• a second voltage terminal, for receiving voltage outputted by said first voltage terminal, and outputting said voltage to said notebook computer;
• a first protection loop including a switch module and a control module, wherein said switch module is disposed between said first voltage terminal and said second voltage terminal, and said control module is coupled separately to said first voltage terminal and said switch module, said control module electrically conducts said switch module to transmit voltage to said second voltage terminal when said control module receives said voltage outputted by said first voltage terminal and complying with a predetermined voltage of said control module;
• a second protection loop having an input terminal coupled between said first voltage terminal and said control module and an output terminal coupled between said switch module and said second voltage terminal, and said control module cuts said switch module when said control module receives voltage outputted by said first voltage terminal and not complying with said predetermined voltage, and said voltage is transmitted to said second protection loop;
• and
• a discharge loop, coupled between an output terminal of said second protection loop and said second voltage terminal, for receiving said voltage outputted by said second protection loop and not complying with said predetermined voltage.