These Schottky-clamped circuits are designed to be used in high-performance memory-decoding or data-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 used with high-speed memories, the delay times of these decoders are usually less than the typical access time of the memory. This means that the effective system delay introduced by the decoder is negligible. The 74LS138 decodes one-of-eight lines, based upon the conditions at the three binary select inputs and the three enable inputs. Two active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented with no external inverters, and a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications. The 74LS139 comprises two separate two-line-to-four line decoders in a single package. The active-low enable input can be used as a data line in demultiplexing applications.
Specifications :-
- Supply Voltage : 4.75 – 5.25V
- LOW Level Input Voltage : 0.8V
- HIGH Level Output Current : -0.4mA
- LOW Level Output Current : 8mA
- Free Air Operating Temperature : 70°C
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