Jump to content
Electronics-Lab.com Community

DIO Protection

Recommended Posts


I have a design question at hand:

I have a group of DIO lines, attached to an FPGA, running +3.3V signal levels. Obviously I would like to drive the signals with buffers, which is simple enough. The problem is the outside world of this device has the probability of pulling the DIO lines up to +28V (this would be an accident, not a common occurance). I've been searching for SMT or BGA solutions to this problem (ie. a buffer with this much protection on the output side) and have found none. If, by chance, anyone knows of any ICs that are capable of such a feat, I would greatly appreciate it. In the event no one knows of any individual ICs that would accomplish this task, a discrete component solution will have to do. If anyone has any recommendations, perhaps even an example schematic, it would be appreciated (using Zeners, resistor networks, etc.)

thanks for any help!

Link to comment
Share on other sites

  • 3 weeks later...

By resistor and zener you mean:

DIO ---/\/\/--------- DIO OUT
/ \

I choose a zener with zener voltage equal to the DIO voltage level .. but what about the resistor ... isn't the resistor going to cause a voltage drop? what is an ideal value for a 3.3V level ?

Thanks for the help!

Link to comment
Share on other sites

The MOV might be the best choice since you are only using 3 volts. Yes, you will have a voltage drop across the resistor. You must always have a larger input than the zener voltage to make this workable. Your voltage drop will be the value of Vinput - Vzener. This voltage drop divided by the resistor value will determine the current of your circuit.


Link to comment
Share on other sites


My setup requires the protection to be "resetable" .. as in not a fuse blown but just protection that won't stop the system from running. Also, is this setup applicable to a DIO line? The circuit shown is for a power supply...

(my thanks to everyone who has been replying!!)

Link to comment
Share on other sites

  • 1 month later...

Join the conversation

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

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.

  • Create New...