Pin-compatibility

In electronics, pin-compatible devices are electronic components, generally integrated circuits or expansion cards, sharing a common footprint and with the same functions assigned or usable on the same pins. Pin compatibility is a property desired by systems integrators as it allows a product to be updated without redesigning printed circuit boards, which can reduce costs and decrease time to market.

Although devices which are pin-compatible share a common footprint, they are not necessarily electrically or thermally compatible. As a result, manufacturers often specify devices as being either pin-to-pin or drop-in compatible. Pin-compatible devices are generally produced to allow upgrading within a single product line, to allow end-of-life devices to be replaced with newer equivalents, or to compete with the equivalent products of other manufacturers.

Pin-to-pin compatible devices share an assignment of functions to pins, but may have differing electrical characteristics (supply voltages, or oscillator frequencies) or thermal characteristics (TDPs, reflow curves, or temperature tolerances). As a result, their use in a system may require that portions of the system, such as its power delivery subsystem, be adapted to fit the new component.

A common example of pin-to-pin compatible devices which may not be electrically compatible are the 7400 series integrated circuits. The 7400 series devices have been produced on a number of different manufacturing processes, but have retained the same pinouts throughout. For example, all 7405 devices provide six NOT gates (or inverters) but may have incompatible supply voltage tolerances.

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