Switching battery charging systems and methods

Abstract

Embodiments of the present invention include techniques for charging a battery using a switching regulator. Some embodiments include programmable switching battery chargers that can be configured using digital techniques. Other embodiments include switching battery chargers that modify the battery current based on sensed circuit conditions such as battery voltage or input current to the switching regulator. In one embodiment, the present invention includes a USB battery charger.

1 . An integrated circuit comprising:
 a switching circuit to provide a switching signal to the control terminal of a switching transistor, the switching transistor having a first terminal to receive power from a power source, a second terminal to provide power to a battery through a filter, and a control terminal;   a current control circuit to receive an input signal corresponding to a sensed current and to provide a control signal to the switching circuit to control the sensed current,   wherein an output current into the battery from the second terminal of the switching transistor is greater than an input current into the first terminal of the switching transistor from the power source,   and wherein the output current is reduced, in a current control mode, as a voltage on the battery increases.   
     
     
         2 . The integrated circuit of  claim 1  further comprising a voltage control circuit to receive an input signal corresponding to a sensed voltage on the battery and to provide a control signal to the switching circuit to control the sensed voltage. 
     
     
         3 . The integrated circuit of  claim 2  wherein the integrated circuit is operable in the current control mode when a voltage on the battery is below a threshold, and wherein the integrated circuit is operable in a voltage control mode when the voltage on the battery increases above the threshold. 
     
     
         4 . The integrated circuit of  claim 2  wherein current control circuit has an output and the voltage control circuit has an output, and wherein the output of the current control circuit is coupled to the output of the voltage control circuit, and wherein the output of the voltage control circuit and the output of the current control circuit are coupled to an input of the switching circuit. 
     
     
         5 . The integrated circuit of  claim 1  wherein the switching transistor is an MOS transistor. 
     
     
         6 . The integrated circuit of  claim 1  wherein the sensed current is a current from the power source to the first input of the switching transistor. 
     
     
         7 . The integrated circuit of  claim 1  wherein the sensed current is a current from the filter to the battery. 
     
     
         8 . The integrated circuit of  claim 1  wherein the input signal to the current control circuit is generated across a resistor. 
     
     
         9 . The integrated circuit of  claim 1  further comprising an analog control circuit for generating the input signal corresponding to the sensed current. 
     
     
         10 . The integrated circuit of  claim 1  further comprising a digital-to-analog converter for generating the input signal corresponding to the sensed current.