recommended state of un connected IOs

[adi2]

Posted on April 19, 2005 at 06:08

recommended state of un connected IOs

[adi2]

Posted on April 17, 2005 at 09:40

Hi !!

what is the recommended state of un connected ios ??? input/ output, shall i connected it through a resistor to the gnd ? leave connection open ???

[alok2]

Posted on April 18, 2005 at 02:01

This is explained in datasheets in electrical section. Leaving the IOs as un-connected is not recommended. Pull-dn to gnd or pull-up to Vdd is the recommended state.

[md1]

Posted on April 18, 2005 at 09:25

Why can't put the un-connected I/O pins in push-pull output?

It's the un-connected floating inputs that are normally the problem.

[md1]

Posted on April 18, 2005 at 09:28

This article has a good explanation:

http://massmind.org/techref/logic/xtrapins.htm

[alok2]

Posted on April 19, 2005 at 06:08

Hi MD,

you are right No problem to keep the IO in o/p PP or OD low but The problem appears if the application is used in high noise environment.If the PC is lost because of some problem or ESD, the IO may become i/p floating and cause the consumption. Even o/p if shorted accidently to any signal can cause pb. So, if all possibilities are evaluated, there is always an agreement on external pU/pD.