basic digital electronics

[vaidhyanathan]

why active low devices are preferred to active high devices:?:

 

[emresel]

I think that keeping any input/output at low state, during transitions (ie power up or power down) is easier than keeping it high state. May be it is the reason.
By the way i am not sure if there is that kind of trend?

 

[nsypid]

You should read my attached article. This provides some insight about active low. Extract them first.

I saved the pages but i don't remember the address of this website.

 

[subbuindia]

I have another doubt sir,
Plz, explain it.
The card reader has units are cards/minutes. What is the significance of 'cards' here?

Thanks.........

 

[milind.a.kulkarni]

I will like to add one more point for active high and active low devices....

In case of Active Low devices - some time reset kind of staff...it is easy to sample the transistion for Processor core, also in case of Active High devices open circuit or Pin floating kind of situation may lead mal-functioning of device

I think this meight be one of the reason....

Good Luck

 

[HTA]

With active Low outputs it is easy to wire-or outputs, or use Tri-state outputs and use an external pull-up resitor to have a clear inactive state(no driver current needed). Usually the active low outputs are faster because the internal driver circuit is easier to implement. Control and command signals like read, write or enable are most time active low.