Patent ID: 7417407

Claim:
A circuit for charging a battery combined with a capacitor, the circuit comprising: a power supply adapted to be connected to the capacitor and the battery for charging the capacitor and the battery; an electronic switch having a first switch terminal connected to the power supply, a second switch terminal, and a control terminal, the electronic switch being responsive to a control signal applied to the control terminal to switch between a conducting state to allow current flow between the first and second switch terminals and a non-conducting state to prevent current flow between the first and second switch terminals, wherein current flow between the first and second switch terminals charges the battery; wherein the battery has first and second battery terminals, the capacitor has first and second capacitor terminals, and the power supply has first and second power supply terminals, and wherein the first power supply terminal is adapted to be connected to both the first capacitor terminal and the first switch terminal, and the second power supply terminal is adapted to be connected to both the second capacitor terminal and the second battery terminal; an inductor having first and second inductor terminals, the first inductor terminal connected to the second switch terminal, the second inductor terminal adapted to be connected to the first battery terminal; a control device connected to the switch control terminal, the control device operable to generate a control signal to continuously switch the electronic switch between the conducting and non-conducting states to charge the battery, and a blocking diode having a cathode and an anode, the cathode connected to the second switch terminal and the anode connected to the second inductor terminal, wherein the blocking diode is controlled by voltage levels of the capacitor and the battery without using a switching circuit; wherein the circuit is configured such that i) after the battery has supplied a surge current, the circuit rapidly recharges the battery to its fully charged state; ii) the battery does not experience long periods of time in a partially charged state; and iii) when the battery is to be charged, the capacitor does not need to be discharged, thus shielding the battery from surging caused by a demand put on the circuit.