Supply current drops with NI 9028

[yuntanyang]

I use NI 9028 to measure my circuit. I connect Sup and AI0 at circuit power jumper ends, and connect COM to GND. The normal supply power is 5.5V and 0.45A, it drops to 0.34A ( at 5.5V) when I connect NI 9028. Can someone help? Thanks.

[macncheese]

Hello yuntanyang,

do you have the part number of your device?

I couldn't find anything with the number 9028.

[yuntanyang]

Sorry, it was typo. The device is NI 9208 with max current up to +/- 20mA. I wonder if I need to add an extra power to 9208 to serve as a SMU. Thanks.

[macncheese]

Hello yuntanyang,

I don’t understand clear enough how are you setting the system.

Take a look at figures 3 and 4 in the specifications sheet using this link.