These devices each contain an 8-bit binary counter that feeds an 8-bit storage register. The storage register has parallel outputs. Separate clocks are provided for both the binary counter and storage register. The binary counter features a direct clear input CCLR\ and a count enable input CCKEN\. For cascading, a ripple carry output RCO\ is provided. Expansion is easily accomplished for two stages by connecting RCO\ of the first stage to CCKEN\ of the second stage. Cascading for larger count chains can be accomplished by connecting RCO\ of each stage to CCK of the following stage.
Both the counter and register clocks are positive-edge triggered. If the user wishes to connect both clocks together, the counter state will always be one count ahead of the register. Internal circuitry prevents clocking from the clock enable.
8-Bit Counter with Register
Parallel Register Outputs
Choice of 3-State ('LS590) or Open-Collector ('LS591) Register Outputs