PXI-6570 to floating DUT Vss

[cspear]

Hello,

I have a DUT with a ground that is floating 3.3V above earth ground.  Vss of the DUT is set to -3.3V (relative to DUT gnd) which makes Vss equivalent to earth ground.  Can I hook the 6570 ground pins to DUT Vss without harming the 6570 functionality?  The idea is to allow me to use the 6570 with positive logic voltage levels, relative to earth ground, but the DUT would see negative voltage levels relative to DUT ground.  My requirements are V_IL < -3V and V_IH > -1V.

[santo_13]

That sounds like a good idea.

1. If you can always guarantee that Vss is earth ground
2. 6570 GND and DGS connected to Vss
3. None of the 6570 channel experience more than 6V (7V in extended mode) with respect to Vss
4. Based on your requirement, you will configure 6570 with V_IL 0.3V and V_IH 2.3V (you would vary the VIL, VIH levels as and when you vary Vss)

Caution!

• If modified levels sheet is not applied, the channels will be at 0V i.e., Vss (which may or may not damage the DUT)
• Careful in power-up order and order of instrument configuration order
• Limited voltage levels up to Vss + 6V
• If used for production test, the continuity and leakage test implementation and measurements need to be offset

Though all these are theoretically possible, I would definitely recommend you to set up a proof of concept board with DUT with adequate current limiting resistors and verify the actual behaviour as expected.