SDLS190 - DECEMBER 1982 - REVISED MARCH 1988
PRODUCTION DATA documents contain information current as of publicationdate. Products conform to specifications per the terms of Texas Instrumentsstandard warranty. Production processing does not necessarily include testingof all parameters.
These devices consist of bus transceiver circuits with 3-state or open-collectoroutputs, D-type flip-flops, and control circuitry arranged for multiplexedtransmission of data directly from the input bus or from the internal registers.Data on the A or B bus will be clocked into the registers on the low-to-hightransition of the appropriate clock pin (CAB or CBA). The following examplesdemonstrate the four fundamental bus-management functions that can be performedwith the octal bus transceivers and registers.
Enable (G\) and direction (DIR) pins are provided to controlthe transceiver functions. In the transceiver mode, data present at the high-impedanceport may be stored in either register or in both. The select controls (SABand SBA) can multiplex stored and real-time (transparent mode) data. The directioncontrol determines which bus will receive data when enable G\ isactive (low). In the isolation mode (control G\ high), A data maybe stored in one register and/or B data may be stored in the other register.
When an output function is disabled, the input function is still enabledand may be used to store and transmit data. Only one of the two buses, A orB, may be driven at a time.
The SN54' family is characterized for operation over the full militarytemperature range of -55°C to 125°C. The SN74' family is characterizedfor operation from 0° to 70°C.
View more information about generic part numbers:SN74LS646, SN74LS647, SN74LS648, SN74LS649
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