cn-0209

Hi,

      I need to design a universal analog input module .I have referred to CN-0209.But I could not understand the purpose of ADG442 used in the circuit.Can I get help?

Regards,

Divya

  • Hi,

         Thank you so much.

    If I double the circuit as you have mentioned in the previous reply(point number 2),then should I double the isolators too?

    Attached herewith is the schematic for cn-0209 which I got from "design and integration files" provided in your site.Can you tell me the purpose of components marked D9,D1,D21,R13,etc used in the schematic?

    Regards,

    Divya

    EVAL-CN0209-SDPZ-SCH-RevB.pdf
  • 0
    •  Analog Employees 
    on Mar 7, 2014 10:57 PM

    Hi Divya,

    In terms of isolation if you double the circuit, you would only need to isolate the chip selects for the second AD7193 and ADG1414. In fact if you do not plan to use the 2 interrupt lines from the ADT7310 (INT1, INT2) you could instead use these two channels for the 2 chip selects instead and wouldn't need any additional isolators. With INT1, INT2 not isolated you can still access the ADT7310's over-temperature information over SPI if desired (e.g. poll this information periodically).

    • The bidirectional TVS diodes (D9, D5, D11, D14, D17, D20), device number SM6T12CA; These TVS devices have a 12V breakdown voltage. The purpose of these devices is to clamp the input to ±12V during any transient EMC events (ESD / EFT / Surge).
    • The purpose of the schottkey diodes to the supplies and ground (e.g. D21, D1) along with the resistor (e.g. R13 1.5kohm) is to limit the voltage presented to the inputs of the IC devices so as not to damage these devices. As the TVS clamps to ~±12V and the supplies are ±15V, this is likely not a problem, though it does add an extra level of protection during severely harsh transients. During severely harsh transients the 12V TVS may clamp to something as high as 21.7V during the transient...

    Regards,

    Derrick


  • Hi,

       In my project,I require atleast two UART and two CAN interfaces to enable the communication of the Analog Input Module  with the CPU .So a controller having two UART and two CAN interfaces is necessary ,right?So can AduCM361 be used here?Is ADSP-CM402F/CM403F/CM407F/CM408F suitable here?Please help me regarding the microcontroller selection.

    Regards,

    Divya

  • Hi,

         As I mentioned in my previous post,I require a microcontroller with atleast two UART and two CAN .So if I use the ADuCM361,the is it possible to add the required UART and CAN to the processor?

    Regards,

    Divya

  • 0
    •  Analog Employees 
    on Mar 21, 2014 6:30 PM

    Hi Divya,

    The ADuCM360 has UART but not CAN interfaces. Some options:

    • You could use the AD7193 24-bit ADC and connect this to a microcontroller that supports the interfaces and processing you require.
    • Another alternative is to use the ADuCM360 as the ADC and use it's Cortex M3 core to perform some of the calibration/linearization for the input. Then connect this to a microcontroller that handles all the communications protocols over UART and CAN.
    • The ADSP-CM402F/CM403F/CM407F/CM408F do have both UART and CAN which you require. That said these devices do not have a 24-bit precision sigma-delta ADC nor an integrated PGA. This would make precision thermocouple measurements difficult. That said it could be possible to use the processor and peripherals of these devices and connect this to an AD7193 ADC for your precision thermocouple and RTD measurements.

    In relation to CAN I should mention the ADM3051/3052/3053/3054, which are a family of CAN transceiver products. The ADM3051 is a non-isolated transciever, and the rest of the family are all isolated transcievers. In fact the ADM3054 also provides isolated power using isoPower technology.

    Regards,

    Derrick