Reversible buck or boost converter that determines boost output current from sensed boost input current

摘要

A reversible buck or boost converter is operable in a buck mode and in a boost mode. In the buck mode, the converter receives a supply voltage via an input terminal and generates a charging current that is supplied to a battery, thereby charging the battery. The supply voltage is also supplied through the converter to an output terminal. In a boost mode, the converter receives power from the battery and generates a supply current and voltage that is output onto the output terminal. The same single current sense resistor is used both to control the charging current in the buck mode and to control a constant current supplied to the output terminal in the boost mode. The output current is controlled to be constant, regardless of changes in the in the battery voltage and changes in the output voltage.

主权项

1. An integrated circuit adapted for use with a current sense resistor, an inductor, a battery and an output capacitor, wherein the current sense resistor, the inductor, the battery and the output capacitor are external to the integrated circuit, the integrated circuit comprising:
a first terminal VIN; a second terminal SW; a third terminal CSP; a fourth terminal CSM; a fifth terminal VOUT; a sixth terminal PGND; a first switch connected directly between the fifth terminal and the second terminal; a second switch connected directly between the second terminal and the sixth terminal; and a control circuit operable in a buck mode and in a boost mode, wherein in the buck mode the first and second switches are controlled such that a first current flows in a first current path out of the integrated circuit from the second terminal, through the inductor, through the current sense resistor, and into the battery thereby charging the battery, wherein the current sense resistor is coupled between the third and fourth terminals, and wherein the output capacitor is coupled between the fifth and sixth terminals, wherein in the boost mode the first and second switches are controlled such that a second current flows in a second current path from the battery, through the current sense resistor, through the inductor, and into the integrated circuit via the second terminal, wherein the control circuit controls a magnitude of the first current in the buck mode at least in part by detecting a magnitude of the first current as a voltage drop across the sense resistor, wherein the control circuit controls a magnitude of a third current in the boost mode at least in part by detecting a magnitude of the second current as a voltage drop across the sense resistor, and wherein the third current in the boost mode flows out of the integrated circuit via the fifth terminal.