74LVC163

应用领域

The 74LVC163 is a synchronous presettable binary counter which features an internal look-ahead carry and can be used for high-speed counting. Synchronous operation is provided by having all flip-flops clocked simultaneously on the positive-going edge of the clock (pin CP). The outputs (pins Q0 to Q3) of the counters may be preset to a HIGH-level or LOW-level. A LOW-level at the parallel enable input (pin PE) disables the counting action and causes the data at the data inputs (pins D0 to D3) to be loaded into the counter on the positive-going edge of the clock (provided that the set-up and hold time requirements for PE are met). Preset takes place regardless of the levels at count enable inputs (pin CEP and CET). A LOW-level at the master reset input (pin MR) sets all four outputs of the flip-flops (pins Q0 to Q3) to LOW-level after the next positive-going transition on the clock input (pin CP) (provided that the set-up and hold time requirements for PE are met). This action occurs rega