<[email protected]> wrote in message
news:[email protected] oups.com...
> Hi,
> There chips with the mixture of Active HIGH and Active LOW signals.

> OR it simply choice of designers / manufacturers?

Yes the designer can define a signal to be active High or active Low - it's
his choice.

However... In general P type devices switch slower than N type. This means
that many devices have slightly different rise and fall times - eg the fall
time 5V->0V is faster than the rise time 0V->5V. This means that if you need
a fast edge for a signal (lets call it a "Ready" signal) then you use the
falling edge because thats faster. Therefore its natural to define Ready =
True = 0V. That makes it an Active Low signal.