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Function Specific Integrated Circuits—FSICs

A Function-Specific IC is a programmable integrated circuit that has been pre-programmed to perform only a single function. They are similar to ASICs in the sense that they are specifically designed for a specific purpose and can significantly reduce component count as well as total cost of a circuit. Unlike ASICs, they are available in low quantities at low cost and have very short development cycles.

An example of a FSIC is a circuit similar to the venerable NE555 timer developed by Signetics in the early days of integrated circuits and subsequently produced by a wide assortment of manufacturers.

Unlike the '555, the FSIC version requires no external components for operation, although they may be used when beneficial. When used as a time delay, versions may be selected with preset delay times with digital precision and no external components. When a field-adjustable delay time is needed, other versions may be selected with digital adjustment features.

Other examples include the window comparator model. It also features a lack of discrete component requirements. Comparator threshold levels can be set by switch closure when the input is at the desired threshold. Existing circuits may use more than 25 components to implement this function of a single FSIC. Over 250 such functions have been chosen for implementation.