PXI-4461 input protection?

[janaf]

Hi,

Is there any specification for the PXI-4461 input protection? I can not find any mention of it in the datasheet.

By misstake I connected an input to 60VDC and to my surprise it survived

[Davidek]

Hi Janaf

From the manual the PXI-4461 Analog Input looks like this:

Input Overvoltage Protection

Differential configuration ............... ±42.4 Vpk

Pseudodifferential configuration

Positive terminal......................... ±42.4 Vpk

Negative terminal (shield) .......... ±10.0 Vpk

Best Regards

David

NISW

[janaf]

Back to this old question.

Today one inputs of one 4461 was floating around like unproperly grounded.

When I pulled the unit out I could right away see that a big 49.9 ohm resistor on the input was fried. Confirmed with an ohm meter.

I am also concerned about how / where thet input DC blocking works? With 50 ohms to ground and 40V DC over it I understand the resistor would fry immediately.....

So now my question is: is there a schematic / block diagram of what the input looks like? I do not want the smoked resistor problem to happen again.

[janaf]

Thanks DaviDek,

The +/- 42.4V is also the maximum measurement range, so I gguess there is no separate overvoltage protection "absolute maximum" than that. Or at least not specified. A bit scary not to know if there is some safety margin above the max reading range..

Still, it would be good to have a block diagram on what the inputs look like in terms of DC/AC, differential / single ended, gain setting etc...