M74HC166

The M54/74HC166 is a high speed C²MOS 8 BITPISO SHIFT REGISTER fabricated in silicon gate C²MOStechnology.Ithasthesamehighspeedper-formance ofLSTTLcombined with trueCMOSlowpowerconsumption.

Itconsistsof parallel orserialinputsandaserial-out8-bit shift register with gated clock inputs and anoverriding clear input. The parallel-in or serial-inmodes are controlled by the SHIFT/LOAD input.WhentheSHIFT/LOAD inputisheldhigh, theserialdatainputisenabledandtheeightflipflopsperformserialshiftingwitheachclockpulse.Whenheldlow,theparalleldata inputs are enabled and syn-chronous loading occurs on the next clock pulse.Clocking is accomplished on the low-to-high leveledgeoftheclockpulse. TheCLOCK-INHIBITinputshould be changed to the high only while theCLOCKinput isheldhigh. Adirectclearinput over-rides all other inputs, including the clock, and setsallflip-flops tozero. Functional detailsareshowninthe truthtable andthe timing chart.

All inputs are equipped with protection circuitsagainst static discharge and transient excess volt-age.