Jump to content
Electronics-Lab.com Community

CMOS...floating inputs


jrcfg
 Share

Recommended Posts

I have read many times in various forums that allowing an input to float is a bad idea...that unused inputs should be pulled up or down.  I always do just that as a result. 

Just so I know.... why, specifically, is it a bad idea to float a CMOS input??

And feel free to get technical.... ;D

Link to comment
Share on other sites

Hi Jrcfg,
A Cmos input has an extremely high resistance and will:
1) Get damaged by any nearby static electricity.
2) Capacitively pick-up nearby signals resulting in a wrong or random output.
3) Maybe oscillate at a very high frequency if it picks-up its own output.
4) Dissipate power because it operates linear instead of logic switching. ;D

I only used a little geek-talk!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...