These Schottky-clamped TTL MSI circults are designed to be used in high-performance memory-decoding or date-routing applications requiring very short propagation delay times. In high-performance memory systems, these decoders can be used to minimize the effects of system decoding. When employed with high-
speed memories utilizing a fast-enable circurt, the delay times of these decoders and the enable tirme of the memory are usually less than the typical access time of the memory. This means that the ettective system delay introduced by the Schortky-clamped system decoder is negligible.
The circuit comprises two indlvidual two-line to four-line decoders in a single package. The active-low enable input can be used as a date line in demultiplexing applications.
All of these decoders/demultiplexers feature fully buffered inputs, each of which represents onty one normalized load to its driving circuit. All inputs are clamped with high-performance Schottky diodes to suppress line-ringing and to simplity system design. The SN54LS139A and SN54S139 are characterized for operation range of-550C to 125C. The SN74LS139A and SN74S139A are characterized for operatlon from 0℃ to 70℃.
(Picture:Pinout / Diagram)
