Patent ID: 8045353
Filing Date: 2011-10-25
Classification: H01L

Abstract:
1. A digital integrated circuit having selectable supply voltage compatibility comprising: core logic, a core logic supply voltage bus connected to said core logic, a low-voltage supply input pad connected to said core logic supply voltage bus, one or more digitally switch able ballast devices having an input end connected to a specific high-voltage supply input pad and its output end connected to said core logic supply voltage bus, a control block associated with each said ballast device, having a control input connected to said specific high-voltage supply input pad and its output connected to the control input of the corresponding ballast device, the arrangement being such that when one of said specific high-voltage supply input pads is connected to the input supply with all other supply input pads being left unconnected, then the corresponding ballast device is enabled and provides a supply voltage reduced to the corelogic operating voltage level to the core logic, while when the input supply is connected to said low-voltage supply input pad and all said specific high-voltage supply input pads are left unconnected then all said ballast devices are disabled and the input supply voltage is directly fed to the core logic supply bus.