AT3600 LSBX test compensation

Product : AT3600Serial Number : N/AFirmware : N/ASoftware : N/A

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Question : Hello Tim, A customer have problem of AT3600 LSBX test. Inductance value is 56nH without DC bias, AT3600 can perform well. When apply 80A DC bias, nominal value should be around 51nH, AT3600 LSBX test will get a negative result. Signal used 0.1V@100kHz. Before run LSBX test, Customer passed compensate the fixture with DC1000 connected, what strange is just after compensated, measure a short circuit products will get a negative result. Questions are: 1, it mostly like caused by leads of fixture, is that possible also caused by AT3600 calibration? 2, What's the recommend signal for 50nH inductance? on user manual, no recommend signal for such low value. 3, What's your further suggestions on this problem? 4, a related problem is DC1000 output current. customer tried 200A bias, 8 sets DC1000 should be ok. however customer find 8 sets DC1000 can't generate 200A, will show error. Up to 10 sets DC1000 then can work well. I guess this caused by DC resistance of the bias current loop circuit, because DC1000 limited output voltage at 5V. if the DC resistance is high enough, then DC1000 can't generate 25A. Is this correct? is there any other cause of this problem? Thank you very much! Regards Alvin Huang

Dear Richard,

Thank you for help.
LS test at same signal works well.
OC and SC compensation performed and passed at the LSBX test.
however after compensation, measure the short circuit part, will get a significant negative results, normally this result should be very small, close to 0.
It looks like the compensation process doesn't work?
Is that more likely cause by the DC1000 HW is not latest? without output choke? Or DC1000 has additional 0.4A output when set 0.

It's possible caused by AT3600 or DC1000 faulty, but I need find out more accurate information, otherwise after get customer units serviced, problem still there will be a trouble.

Maybe get a sample ship to UK is a good choise.

Thank you!
Alvin Huang