Patent ID: 8610405
Filing Date: 2013-12-17
Classification: H02J,H02M

Abstract:
1. A charge and discharge circuit of a secondary battery, the charge and discharge circuit being capable of charging the secondary battery by a power source voltage and of supplying power from the secondary battery to an external device, the charge and discharge circuit comprising: a bidirectional regulator capable of adjusting a current or a voltage in both of a charge direction of feeding the current to a secondary battery side and a discharge direction of feeding the current from the secondary battery to an external device side; a charge and discharge detecting circuit for detecting a direction of the current flowing in the secondary battery; a switching control circuit for switching an operation direction of the bidirectional regulator into the charge direction or the discharge direction based on a detection result of the charge and discharge detecting circuit; and a battery voltage detection circuit for detecting a battery voltage of the secondary battery; wherein the charge and discharge detecting circuit includes: wherein when the battery voltage detection circuit detects that the battery voltage of the second battery is lower than a first threshold voltage which is higher than a lowest operation voltage of the external device during discharge from the secondary battery to the external device, the bidirectional regulator starts a voltage raising operation to perform power supply to the external device; and wherein when the battery voltage direction circuit detects that the battery voltage of the secondary battery exceeds a second threshold voltage which is higher than the first threshold voltage during discharge from the secondary battery to the external device, the bidirectional regulator stops the voltage raising operation.