How to read datasheets
In a timing diagram, what is meant by the notation in which an address or data bus is drawn as two parallel lines, upper and lower, that cross in an × shape here and there?
- ASections with parallel lines indicate that the signal is oscillating rapidly between H and L
- BSections with parallel lines indicate that the value is valid, and the value changes at each ×
- CEach × indicates that the output goes into a high-impedance (open) state at that moment
Show answer and explanation
Answer: B. Sections with parallel lines indicate that the value is valid, and the value changes at each ×
In a multi-bit bus, whether each bit is H or L depends on the data, so both the H and L lines are drawn in parallel to show a section where "some value is valid." The × crossing marks the point where that value changes, and setup and hold times are shown as the interval between this transition and the clock edge. High impedance is generally drawn as a single line at mid-height, and sections where the value is invalid are drawn with hatching. Check the legend in the datasheet for notation conventions.