Digital input protection on Digital Discovery

[Someone]

Hello,

I read the following lines in the documentation of some other USB DAQ:

Quote

Caution Do not leave a voltage above 3.3 V connected on any DIO line for extended periods of time when the device is powered off. This may lead to long term reliability issues.

As I have no real electronics background I'm asking myself if such a statement is also valid for Digital Discovery or Analog Discovery 2 input pins and what state do these pins have in powered off state?

[attila]

Hi @Someone

It is not recommended to apply voltage to any unsupplied device or IC since in this case the protection diodes will have to handle it.

The Digital Discovery IOs (24-49) as input are 5V compatible with level translator. The output voltage is adjustable between 1.2V and 3.3V, this also adjusts the input threshold between ~0.5V and ~1.5V The inputs (0:23) are also 5V compatible.

The Analog Discovery DIOs are also compatible with 5V but this through protection circuit, so it will sink more current than DD's translator solution. The output voltage is fixed 3.3V The input threshold is ~1.5V and ~0.5V with the 5th and 7th configurations.

Both are protected up to +/-20V

For more details see the reference pages and WaveForms app Help
https://digilent.com/reference/test-and-measurement/digital-discovery/start
https://digilent.com/reference/test-and-measurement/analog-discovery-2/start