This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
There are two primary issues associated with slow and floating inputs.
(1) Shoot-through current
Figure 1. Typical CMOS input structure with the control voltage for each input MOSFET shown.
CMOS logic devices depend on their inputs being at either a logic HIGH or a logic LOW.
When the input is 'somewhere in the middle,' then it's easy to see from Figure 1 that both MOSFETs on the input can be turned on, which can cause a significant amount of shoot-through current. It is best to transition through this voltage region as quickly as possible to prevent shoot-through current.
(Thanks to kai klaas69 for this image)
When the input lingers near the threshold value (typically 1/2*Vcc) then the output can oscillate between the LOW and HIGH state uncontrollably.
For any CMOS device that does not have Schmitt-trigger inputs, the datasheet defines a minimum input transition rate that will prevent this from happening.
For more information, see the application report Implications of Slow or Floating CMOS Inputs
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.