Patent ID: 7701173

Claim:
A USB-compliant charging and power supply circuit comprising: switch-mode battery charging circuitry for receiving power from an external power source and for supplying output power, through an output node, to an electronic system of an electronic communication device and to a battery, said switch-mode battery charging circuitry having an integrated circuit and an inductor, said integrated circuit arranged to cooperate with said inductor to provide current of said output power of greater magnitude than current of said power received from said external power source; battery isolation circuitry including a semiconductor switch connecting the output node to said battery, the battery isolation circuitry sensing voltage at said output node and variably restricting current to said battery when said voltage is below a minimum voltage value by operationally controlling said semiconductor switch as current passes through it; and additional circuitry in electrical communication with said battery isolation circuitry for receiving feedback from the electronic system and, in response to the feedback, adjusting the minimum voltage value in relation to requirements of said electronic system; whereby during variable current restriction said electronic system is supplied required power with said battery being supplied any additional available power.