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Using ADALM1000 AIN and CHA as kelvin connection

Category: Hardware
Product Number: ADALM1000 rev.F
Software Version: Raw pyhton command lines

Hi, I m having some issue trying to use ADALM1000 as a kelvin connector. I want to get accurate force voltage at CHA. 

At board revision F, I found that I can open S4 with: 

devx.ctrl_transfer(DevID, 0x40, 0x51, 34, 0, 0, 0, 100)

Then I made a proof test with 2 series resistors like below: 

In this case, If I apply 1V at CHA and measuring half of this voltage at AIN, I was expecting to have something close to 2V at CHA, while having accurate 1V at AIN. But I always get 1V at CHA. What am I missing?

Thanks in advance.



proof test reloaded
[edited by: dpmioni at 8:04 AM (GMT -5) on 13 Feb 2023]
Parents
  • Hello:

    Sorry but the AIN Split Input/Outpup mode does not work that way. That schematic of the SMU output driver is incomplete. The analog feedback path from the driver output (CHA) is always connected back to the driver inverting input (with the non-inverting input always connected to the set point DAC). So it is not possible to use the AIN as a SENSE input as you are attempting. I would add a link to the full design schematic of the F revision but I can't find it right now. I think it is some where on the ADI Wiki.

    The purpose of the AIN pin is to open the SMU feature of simultaneous sourcing and measuring on one single pin and allow  more conventional measuring and sourcing on separate individual pins.

    Sorry if this was somehow confusing.

    Doug

Reply
  • Hello:

    Sorry but the AIN Split Input/Outpup mode does not work that way. That schematic of the SMU output driver is incomplete. The analog feedback path from the driver output (CHA) is always connected back to the driver inverting input (with the non-inverting input always connected to the set point DAC). So it is not possible to use the AIN as a SENSE input as you are attempting. I would add a link to the full design schematic of the F revision but I can't find it right now. I think it is some where on the ADI Wiki.

    The purpose of the AIN pin is to open the SMU feature of simultaneous sourcing and measuring on one single pin and allow  more conventional measuring and sourcing on separate individual pins.

    Sorry if this was somehow confusing.

    Doug

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