DIO line protection

[Jon]

Hello,

I have a task in mind and was hoping for a little bit of guidance.

I have a set (10) of I/O lines coming out of an FPGA.

I would like to protect these lines from over-voltage. The
requirement is if these lines get pulled up to 28V, an IC will protect
these 10 I/O lines, and more importantly, the FPGA. The signals
coming out of the FPGA are 3.3V and thus, I would like an IC that
allows these signals to pass through, but protect the FPGA if the
unfortunate occurs and the lines are pulled high (up to 28V of
protection). This is a small project (in physical size) and thus
TSSOP components are required. I would prefer to use an IC to solve
this problem, but I am also reluctantly open to other solutions with
discrete components (like Zener's). Name/type/model/manufacturer of
required IC would be great.

Thank you for any help!

 

[Spehro Pefhany]

Hello,

I have a task in mind and was hoping for a little bit of guidance.

I have a set (10) of I/O lines coming out of an FPGA.

I would like to protect these lines from over-voltage. The
requirement is if these lines get pulled up to 28V, an IC will protect
these 10 I/O lines, and more importantly, the FPGA. The signals
coming out of the FPGA are 3.3V and thus, I would like an IC that
allows these signals to pass through, but protect the FPGA if the
unfortunate occurs and the lines are pulled high (up to 28V of
protection). This is a small project (in physical size) and thus
TSSOP components are required. I would prefer to use an IC to solve
this problem, but I am also reluctantly open to other solutions with
discrete components (like Zener's). Name/type/model/manufacturer of
required IC would be great.

Simply putting a 10K series resistor on each line (a few networks)
will probably work, but may cause other problems. Zener's diodes'
effect might be helpful.

Best regards,
Spehro Pefhany

 

[Jon]

Simply putting a 10K series resistor on each line (a few networks)
will probably work, but may cause other problems. Zener's diodes'
effect might be helpful.

Best regards,
Spehro Pefhany

I need protection that allows the 3.3V to go through, but protects on
the ouput side (up to 28V). Putting a series resistor will cause a
voltage drop, which doesn't help the situation.