Using CN0395 hardware (EVAL-CN0395-ARDZ), is there a way to easily change the ADN8810 FS current, and control it's output?

Using EVAL-CN0395-ARDZ with ADICUP platform. We are just interested in the ADN8810 portion of the board, as a current source, and would like to control the current output.

  • 0
    •  Analog Employees 
    on Jul 26, 2018 1:15 AM

    Hi Reem,

    Could you have a look at the user guide (EVAL-CN0395-ARDZ Shield [Analog Devices Wiki]  ) there is a section towards the bottom that outlines how to control the current from the ADN8810.

    Cheers,

    Brandon

  • 0
    •  Analog Employees 
    on Jul 26, 2018 10:03 AM

    Hi Reemo,

    The ADN8810 is a 12-bit High Output Current source in which the output current is set by the below equation:

    2f71b9506ce0d3ef470579daf13cc56d.html

    The full scale current is dependent on the value of the sense resistors,  R17_SPACER and R19_SPACER, which uses the following equation:

    2867.2f71b9506ce0d3ef470579daf13cc56d.html

    where in the CN0395 circuit:

    VREF is the voltage reference of the circuit (4.096 V) and RSN is the value of the sense resistors (41.2 Ω). ADN8810 is designed to operate with a 4.096V reference voltage while the sense resistors are variable which can be set to get full scale current output of 300mA. It is best to select precision resistors when choosing values for RSN to have an accurate output voltages.

    With a 4.096 voltage reference and a 41.2Ω sense resistor, the full scale output is set to 9.94mA with a 2.42uA LSB on a 12-bit resolution.

    Hope this helps.

    Regards,

    Glenn Amparo

  • 0
    •  Analog Employees 
    on Jul 28, 2018 12:44 AM

    Ok thanks guys, I see you can use R17_ and R19_SPACER to change RSM for max current.

    And then can you use the app to change the DAC to change the current out?

  • 0
    •  Analog Employees 
    on Jul 30, 2018 6:34 AM

    Hi Reemo,

    The EVAL-CN0395-ARDZ board and is software is designed to work with the installed sensor, TGS8100, from Figaro. The hardware limited full scale current and the source code was written for the limits of the particular sensor. Thus, making hardware changes, setting the current limits, would need the considerations in the sensor used.

    The design can be used as a reference when creating new circuits and the source code can also be used as a reference to new applications.

    Hardware considerations:

    • Absolute maximum ratings of sensor used
    • Changes in sense resistor needs to be calculated to safe operating conditions of current limit
    • Set currents needs to be in range for the ADC on the board
    • Sensor on board can be removed to use different sensors on available slots M1 and P8

    Software considerations:

    • Calibration routines
    • Set points in the currents are calculated for operating conditions of the sensor used
      • Current set when heating the resistor
      • Current set when reading resistor values

    Here are links to the circuit note and the user guides for the board:

    Hope this helps.

    Regards,

    Glenn Amparo