Three-Level Input Model of CY7B993/4V

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    Question: What are the required voltage levels of a three level input? How do you model a three-level input?



      The voltage levels are VIHH, VIMM, and VILL on the data sheet. The ranges for the CY7B993/4V are from 0.87*VCC to V CC for VIHH, from 0.47*VCC to 0.53*VCC for V IMM, and 0.0V to 0.13*VCC for VILL. These values guarantee that the correct value will be detected. The actual thresholds (high threshold = VTHH, low threshold = VTHL) will be between the specified ranges. The voltage thresholds of typical silicon are also shown here. A MID input will typically be detected anywhere from 1.2V to 2.2V, for a 3.3V VCC.

      A pull-up and pull-down resistor can model the three-level inputs of the RoboClockII family. The internal resistor values for the three-level inputs are approximately a 30-Kohm. pull-up and 30-Kohm pull-down.