M74HC651

M74HC651/652 are high speed CMOS OCTAL BUS TRANSCEIVERS AND REGISTERS (3- STATE), fabricated in silicon gate C²MOS technology. They have the same high speed performance of LSTTL combined with trueCMOSlow power consumption. These devices consist of bus transceiver circuits, D-type flip-flops, and control circuitry arranged for multiplexed transmission of data directly from the input bus or from the internal storage registers. EnableGABand GBA are provided to control the transceiver functions.

Select AB and Select BA control pins of M74HC651/652 are provided to select whether real-time or stored data is transfered. A low input level selects real-time data, and a high selects stored data.

Data on the Aor B bus, or both, can be stored in the internal D flip-flops by low-to-high transitions at the appropriate clock pins (CLOCK AB or CLOCK BA) regardless of the select or enable control pins. When select AB and select BA are in the real-time transfer mod e, it is also possible to store data without using  the internal D-type flip-flops by simultaneously enablingGAB and GBA. In this configuration each output reinforces its input. Thus, when all other data sources to the two sets of bus lines are at high impedance, each set of bus lines will remain at its last state. All inputs of M74HC651/652 are equipped with protection circuits against static discharge and transient excess voltage.