MI calibration method of AD5522

HI, baggio. 

I assumed you are referring to this section in the datasheet:

Please see responses to your questions below:

1. Yup, that is correct as it is consistent with what's in the section 4. Be sure to put the part in the Measure I mode. I am not sure as to which signal you refer to as "the reference". If you are referring to the source voltage, the source for both sections will be the FORCE amplifier (FIN).

2 & 3. The SYS_FORCE and SYS_SENSE pins are intended to measure voltage current from and not exactly to force voltage or current into when doing FI and MI calibrations. I personally don't have much experience on using these pins for forcing current during calibration as this is the first time this has been asked. I don't think it will hurt if you try it on your side, though, if it is needed in your application (it would be best if you can tell us the reason why this is important). Just be cautious on the amount of current you're forcing into these pins.

Best regards,
Mac

Hello. MacManato.

Thank you always.  Let me check a little more on the content.

About question 1.

　My question is about "No.4" of the data sheet you showed me.

　I was asking if what I mean by reference signal is the current signal calibrated by the AD5522.

   Signal below?

　I also understood that the measurement connections shown below are correct.

　Q1：Is it possible to connect an ammeter only to SYS_FORCE and measure it to simplify this?
　　　 Delete the red part

About question 2&3.

　Q2：SYS_FORCE is described as Input in "Table 6. Pin Function Descriptions", but is it supposed to be used as a measurement terminal?

　Q3：How should I calibrate EXT MI?

I don't have much experience in this field, so I have a lot of questions, but it would be helpful if you could follow me.

Best Regards.

Hi, baggio. 

We did a more thorough look into this inquiry and can provide you with the current paths for MI calibration for both the internal and external current ranges. Please disregard earlier responses to avoid confusion.

You are correct that this diagram can be simplified. You also don't need the ammeter at the DUT pin, like in your drawing.

For the internal current ranges, please refer to this diagram:

I have drawn blue lines to show you that minimal currents flow through these paths while red arrow shows much of the current. Please note that DUT is left open.

For EXT current range, please see below diagram:

In both cases, consistent with the datasheet, the SYS_FORCE pin will be used to measure current readings to be compared with the MEASOUTx pin reading:

Use the transfer functions table on pages 33-34 of the datasheet to translate your voltage measurements at MEASOUTx to the current readings.

If you have further questions, please let me know.

Best regards,
Mac

Hello. MacManato.

Please tell me more about AD5522's internal MI Calibration.

It is said that calibration can be done by measuring the red line in the figure below, but how much current flows through the blue line? Also, at this time, FOH and MEASVH are shorted, right?

Is it up to the customer to decide whether to calibrate to include the current flowing through the blue wire?

Regarding external resistance calibration, we will discuss this with the customer.

Best Regards.

Hi, baggio. 

The combined leakage of all these paths in blue has to be in the order of a few tens of nA. Even if you force 1mA out of the part, this leakage current can be ignored for calibration.

Best regards,
Mac

Hello. MacManato.

Thank you for answering. I will try to explain to the customer.

If you have any more questions, please let me start a thread to ask them.

Thank you. 

Best regards.