This standard defines the input, output specifications and ac test conditions for devices that are designed to operate in the SSTL_2 logic switching range, nominally 0 V to 2.5 V. The standard may be applied to ICs operating with separate VDD and VDDQ supply voltages. This standard has been developed particularly with the objective of providing a relatively simple upgrade path from MOS push-pull interface designs. The standard is particularly intended to improve operation in situations where busses must be isolated from relatively large stubs.