Patent ID: 6353308
Filing Date: 2002-03-05
Classification: G05F

Abstract:
A method for forming an operating voltage (VCC2) within a first electronic device (1) limited to voltage levels between a maximum level (Vmax) and a minimum level (Vmin) from a voltage supply (Vs2) of a second electronic device (2) wherein the first electronic device is adapted for coupling to and from the first electronic device (1), the method comprising the following combination of steps considered together,coupling the supply voltage (Vs2) of the second electronic device to first (7) and second (8) operating voltage supply blocks of the first electronic device (1) for creating a limited operating voltage (Vcc2) for the first electronic device (1), using the first operating voltage supply block (7) to limit the operating voltage (Vcc2) to a level below the maximum voltage level (V3), determining for the operating voltage (Vcc2) at least a first limiting voltage (V3) that is lower than the maximum voltage (Vmax), comparing the supply voltage (Vs2) to the first limiting voltage (V3) and, if supply voltage (Vs2) is greater than the first limit voltage (V3), activating the first voltage supply block (7) to form the operating voltage (Vcc2) from the supply voltage (Vs2) and limiting the output of the operating voltage supply block to a voltage level (V3) below the maximum voltage (Vmax) and if the supply voltage (Vs2) is substantially smaller than the first limit voltage (V3), and activating the second voltage supply block (8) to form the operating voltage (Vcc2) from the supply voltage (Vs2).