A system for identifying electric device includes a charging/discharging circuit comprised of at least one electric capacitor and one additional electric element, such as an electric resistor or an electric inductance. The charging/discharging circuit is connected to at least one input/output port of a central processing unit and has a particular charging/discharging characteristics based on values of the capacitor and the resistor or the inductance. The particular charging/discharging characteristics provides an identification code of the device. The identification code may be used to identify a particular product in for example a communication link between a central processing unit of a host machine and a peripheral device or be used to identify a particular model of products manufactured in a manufacturing line whereby the same facility may be used to manufacture different models of products thereby effectively reducing the manufacturing costs.
A self-identifying integrated circuit contains a primary function circuit and an immutable, unique identification code, which is presented at an output port thereof upon demand by, an external circuit. The unique identification code may be an N bit digital number or may be a response signal to an interrogating excitation signal. The circuitry to store the unique identification code is fabricated on a microscopic scale such as by a direct-write laser forward transfer of material process or by a laser ablation of select material process. The identification storage means may be disposed on a package substrate or on an integrated circuit die and is permanently encased within the integrated circuit package so as to be protected from alteration by external means.
