tLZOE and tHZOE demystified

Question: Timing specification on some datasheets mentions timings tLZOE(min) and tHZOE(max) as 5 and 20 ns respectively. But foot note 15 mentions at any given temp and voltage tHZOE is less then tLZOE. Please clarify the interpretation of this?

 

Answer:

On the first look, it seems that there is a mistake in the datasheet.  But, please note that these parameters are tested at opposite conditions, i.e. tLZOE is tested at high Vcc, low temp and fast corner whereas tHZOE istested at low Vcc, high temp and slow corner as the former is a min. spec.and the latter is a max. spec. So, at any given temperature and voltage, the design is guaranteed such that tHZOE is less than tLZOE to prevent bus contention.