Built-in charge circuit for secondary battery and secondary battery with the built-in charge circuit

A secondary battery assembly comprising:

• a bare cell;
• a protection circuit interconnected between the bare cell and terminals that are adapted to be coupled to a load, wherein the protection circuit controls the state of charge of the bare cell;
• a charge circuit adapted to process direct current input voltage that has a positive and negative input electrode, wherein the charge circuit provides charge to the bare cell via the protection circuit, wherein the charge circuit defines a positive charge path that extends between the positive electrode and the protection circuit and wherein a first switching device and a charge storage device is positioned along the positive charge path and wherein the charge circuit defines a stored energy discharge path between the storage device and the negative input electrode wherein a first reverse current protection element is positioned along the stored energy discharge path and wherein the charge circuit includes a second reverse current protection element that inhibits damage in a reversed charge connection state to the charge circuit by the flow of reverse current from the negative electrode charge terminal of the charge circuit section to the positive electrode terminal of the protection circuit due to reverse charge on the terminals of the protection circuit that couple to the load,
• wherein the first reverse current protection element comprises a transistor,
• wherein the first reverse current protection element further comprises a parasitic diode connected in parallel to the transistor,
• wherein the second reverse current protection element is interposed between the first reverse current protection element and the negative charge terminal and is configured so as to inhibit the flow of current through the first reverse current protection element when a reverse charge occurs, and
• wherein the second reverse current protection element comprises a transistor having a gate that is coupled to one of the electrode terminals of the protection circuit so that when a reverse current situation occurs, the transistor is turned off to thereby inhibit current flow through the first reverse current protection element.