• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 21 subscribers
  • Views 686 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

SN74LVC1G08: GND pin Floating

Brian Wang0928
Genius 15220 points

Part Number: SN74LVC1G08

My csutomer found that the SN74LVC1G08 can still work when its GND pin is floating. Is there any side-effect with GND pin floating event through the function works normally? Is there any lift-time problem with device?

Regards,

Brian

  • 0
    TI__Guru* 97676 points

    Hi Brian,

    I highly doubt that the part is "working normally" since part of normal operation is sinking current through the ground pin, and obviously it is not doing that.

    There are diodes connecting the ground pin to other pins around the device (part of the intrinsic structure of CMOS on silicon, and ESD protection). It is likely that one of these diodes is allowing ground to sink current, although the ground will be slightly above the usual level (~0.7V).

    I have created a simple illustration to show the different current paths.  The red arrows show the normal current path for outputting a LOW, and the blue arrows show the path when ground is disconnected. I very much simplified the internals of the device for this explanation.

    Ground should always be the first thing connected in any system, and the last to be disconnected -- we will not guarantee the operation of a device when the ground pin is not connected properly during operation.