Post Go back to editing

AD5560 calibration

Category: Hardware
Product Number: AD5560
Software Version: NONE

Hello,

In the AD5560 datasheet, I looked for information related to calibration. However, for the current measurement results, can we only simply adjust by addition or subtraction? For example, when it's 33mA, the error is 75μA. Then, in the data processing of the upper computer, I correct by 75μA. But when it's 10mA or 100mA, this error is no longer 75μA. Is there a solution for this? Another question: Can the AD5560 only measure the voltage it provides itself? If I don't set any voltage output for the AD5560 and directly connect the output to a 2V power source, the MEASOUT won't measure any values. Moreover, the 2V seems to be absorbed by the AD5560 since the voltmeter reads 0V at the output at that time.

Thank you.

Top Replies

    •  Analog Employees 
    Sep 26, 2023 in reply to koob +1 verified

    Hi  ,

    After careful assessment of the inquiry, we found an error on the datasheet, particularly on the snippet you sent. You cannot calibrate the current output of the AD5560 by adjusting the m and c…

  • Hello  ,

    I have moved this query to the Automated Test Equipment (ATE) Community. Someone there should be able to assist you better.

    Best regards,
    Paul

  • Hi  ,

     

    I understand that you have two questions about the AD5560. I will try to clarify each and then provide you answers about them.

     

    1. Your first question is about how to calibrate the current measurement results of the AD5560. You want to know if there is a better way than simply adjusting by addition or subtraction based on the error at a specific current value. The answer is yes, there is a better way. The AD5560 datasheet provides some guidelines for system level calibration on page 42. Images below show steps on how to do it.

     

     

    This process also suggests using a high precision external ammeter to measure the current at different force voltages and current ranges, and then calculate the offset and gain errors for each range (see setup in the snippet below). These errors can be corrected by writing to the offset and gain correction registers on the AD5560.

     

     

    2. For your second question, the AD5560 can measure voltage from an external source provided that you put the force amplifier in high-Z mode using the hardware inhibit function.

    Additionally, you can also achieve the same result in the eval software of AD5560 by disabling DPS mode as highlighted below.

     

     

     

    Upon doing that, you may now be able measure the external voltage source through the MEASOUT pin as illustrated below.

     

    I hope this helps.

     

     

    Regards,

    Gelo

  • hello Gelo,

    Thank you for your response.

    I still have some questions regarding current calibration. After determining the error from the data sheet, what should be done next? It seems there isn't a corresponding register to write into, and we only obtain a fixed error value?

    Regards,

    Koob

  • Hi  ,

    After careful assessment of the inquiry, we found an error on the datasheet, particularly on the snippet you sent. You cannot calibrate the current output of the AD5560 by adjusting the m and c registers of the FIN DAC.
    You can do a two-point calibration. To do this, you need to force two different voltages from the AD5560 at a constant load, for example, +1 and +10 V. While doing that, measure the current through the DUT using an ammeter and compare the value with the current from the MEASOUT.
    At this point, you will have two measurements from MEASOUT and two measurements from the ammeter.
    Treat the measurements from the ammeter as ideal.
    After that, you can compute the offset and gain coefficients from your MEASOUT measurement. Hint: you can do this using the line equation (y = mx + c).

    Regards,

    Gelo