apparently it is easy to damage something by playing around with the XADC-port (of a Zybo-Z7 in this case). I want to read the charging curve of a capacitor. How I thought this could be done I simulated in LTSpice:
300mv are much less than the maximum 1V and I added R5 and R3 because there are no preresisitors inside XADC-ports. I guess this way my hardware should survive the first time converting an analog voltage curve into digital value. But I'm, just guessing so the two questions I have about this are
1. Is this safe?
2. Is there a better way to do this?
and also
3. How sensible are the XADC-Ports really? How high do currents and/or voltages have to be to cause damages? Are maybe the only important rules to prevent short circuits through XADC-hardware by placing a preresistor and prevent voltages above 3.3V?
Thank you!
/edit
Question #4
Would a combination of resistors (one would be enough I think) and Zener-diodes (breakdown at 1V), as you can see below, securely protect any hardware onboard of any mistakes done outside XADC-Pmod? This is just a result of my tiny little knowledge of analog elecronics. Simulation does agree but that is just simulation. Maybe in reality and for a very short time there still could be constellations causing voltages and/or currents that could damage my board...
Or is this schematic below really a secure protection?
Depending on how XADC-hardware looks inside, theoretically a short circuit current would cause high voltages which should also be taken by the diodes, ...I guess. So are resistors maybe not even needed and only Zener-diodes would already give a safe protection of hardware damages?
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yottabyte
Hi,
apparently it is easy to damage something by playing around with the XADC-port (of a Zybo-Z7 in this case). I want to read the charging curve of a capacitor. How I thought this could be done I simulated in LTSpice:
300mv are much less than the maximum 1V and I added R5 and R3 because there are no preresisitors inside XADC-ports. I guess this way my hardware should survive the first time converting an analog voltage curve into digital value. But I'm, just guessing so the two questions I have about this are
1. Is this safe?
2. Is there a better way to do this?
and also
3. How sensible are the XADC-Ports really? How high do currents and/or voltages have to be to cause damages? Are maybe the only important rules to prevent short circuits through XADC-hardware by placing a preresistor and prevent voltages above 3.3V?
Thank you!
/edit
Question #4
Would a combination of resistors (one would be enough I think) and Zener-diodes (breakdown at 1V), as you can see below, securely protect any hardware onboard of any mistakes done outside XADC-Pmod? This is just a result of my tiny little knowledge of analog elecronics. Simulation does agree but that is just simulation. Maybe in reality and for a very short time there still could be constellations causing voltages and/or currents that could damage my board...
Or is this schematic below really a secure protection?
Depending on how XADC-hardware looks inside, theoretically a short circuit current would cause high voltages which should also be taken by the diodes, ...I guess. So are resistors maybe not even needed and only Zener-diodes would already give a safe protection of hardware damages?
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