Patent ID: 7893654

Claim:
A constant-current, constant-voltage and constant-temperature current supply for providing a charge current to a load, comprising: a driving transistor, having a first terminal coupled to a power supply, a control terminal coupled to a node, and a second terminal coupled to the load, the driving transistor for providing the charge current to the load; a sensing transistor, having a first terminal coupled to the power supply, a control terminal coupled to the node, and a second terminal; a pulling low transistor, having a first terminal, a control terminal, and a second terminal coupled to the node, the pulling low transistor being for pulling low the node; a constant voltage controller, coupled to the driving transistor, the sensing transistor and the pulling low transistor, wherein when a voltage across the load rises up and comes close to a first reference voltage, the constant voltage controller pulls up the node, controls the conduction state of the driving transistor and accordingly maintains the voltage across the load at the first reference voltage; and a constant current controller, coupled to the driving transistor, the sensing transistor, the pulling low transistor and the constant voltage controller, wherein when the voltage across the load drops much lower than the first reference voltage, the constant current controller controls the node via a first pull high transistor and the pulling low transistor and thus limits the charge current to be constantly provided to the load.