Bidirectional switch circuit for power banks and the method thereof

A power bank, comprising:

• an input terminal;
• an output terminal;
• a battery;
• a bidirectional switch circuit having a first terminal coupled to the battery, and a second terminal coupled to the output terminal of the power bank;
• and
• a select circuit having a first terminal coupled to the input terminal of the power bank, and a second terminal coupled to the output terminal of the power bank;
• wherein when the input terminal is wired up with a power source, the bidirectional switch circuit works under charge mode that the select circuit connects the input terminal to the output terminal, and a load coupled to the output terminal is powered by the power source, and meanwhile, the battery is charged by the power source via the select circuit and the bidirectional switch circuit;
• when the input terminal is disconnected from the power source, the bidirectional switch circuit works under discharge mode that the select circuit disconnects the input terminal and the output terminal, and the load is powered by the battery via the bidirectional switch circuit;
• wherein the bidirectional switch circuit comprises:
• an inductor having a first terminal and a second terminal, wherein the first terminal is coupled to a first power device to receive a charge voltage, and the second terminal is coupled to a switch node;
• a low side power switch having a first terminal, a second terminal and a control terminal, wherein the first terminal is coupled to the switch node, the second terminal is coupled to a ground reference, and the control terminal is configured to receive a low side control signal;
• a high side power switch set having a first terminal, a second terminal, a third terminal, a fourth terminal and a control terminal, wherein the first terminal and the fourth terminal are coupled together to the switch node, the second terminal is coupled to a second power device to receive a discharge voltage, the third terminal is configured to receive a larger one of the charge voltage and the discharge voltage, and the control terminal is configured to receive a high side control signal;
• and
• a control circuit configured to provide the high side control signal and the low side control signal respectively to the high side power switch set and the low side power switch.