Question about DC2209 and DC2026

Hi All,

Before building up my temperature measurement system (PC--DC2026--DC2209--DC2212) , I have a couple of questions. Please take care of this case.

Q1 and Q2 : Please refer to the attachment.

Q3: Are there any settings and/or adjustments to LTC2983 before temperature measurement?

Q4: I'm going to start our trial production if the demo system works well. In that case you can provide any helpful software?

Regards,

Kazu

Question1and2.pdf
  • Hi @Kazu - apologies for the delayed response!

    A1 - we recommend RC filters instead of LC as there is less chance of ringing with either environmental noise/coupled signals or the internal excitation pulse if the built-in open-circuit detection is used. Please refer to my LTJournal article for more on filtering: 
    http://www.analog.com/media/en/technical-documentation/lt-journal-article/ltjournal-v27n1-00-df-ltc298x-logancummings.pd… 

    A2 - A pull-up resistor will create a voltage across the 1k series resistance and therefore develop an offset in the measured thermocouple value. This will lead to an error in the measured temperature. The LTC2983 provides a built-in open-circuit detection feature that when enabled provides a current pulse into the thermocouple. If the thermocouple is intact, any voltage developed from this current will decay and no error will result. If the thermocouple is open-circuit, a large voltage will remain and be detected by the LTC2983. More info in that article as well as in the datasheet page 57. 

    A3 - You will need to configure the channel assignments to tell the LTC2983 which sensors are connected to which channels as well as to specify the cold-junction compensation sensor channel for the thermocouples. 

    A4 - Please download the Demo Software - TestBench GUI - this is very useful with or without the demo boards as it will let you configure channels and verify their wiring, as well as generate C-code that can be used with our Linduino or other Arduino-Uno compatible boards. 

    LTC2983 Datasheet and Product Info | Analog Devices 

    http://swdownloads.analog.com/ltc2983/installltc2983.zip  (direct link)

    http://www.analog.com/media/en/evaluation-boards-kits/evaluation-software/2983dsmf.pdf  (software manual)

    Hope this helps, let me know if there are any other questions.

    -Logan

  • Hi,

    I have an addtional some questions. Please also take care of this case.

    - Test results I can see on the LTC2983 Testbench GUI can be swept out to CSV file?

    - About LTC2983, I'd like to measure 12ch per 1 sec in two conversion cycle mode. Do you have any sugesstions to

      increase ODR?

    - Is there any tool for installind boot loaders?

    - LTC2983 can be latched-up by unexpected noise and so forth?  Need to take measure to latch-up?

    Regards,

    Kazu

  • Hi Kazu, 

     

     Test results can be captured in a CSV file using the GUI by selecting Evaluate -> Run and Save Output

    You will be prompted for a location to save the csv file. 

    The LTC2983 has a fixed ODR for line frequency rejection. The only way to speed up this part is to use more than one - two LTC2986's should be able to do the 12ch in 1s. Alternatively you may want to look at the AD7124 - it has a few more filter options that can still provide 50/60Hz rejection at faster ODRs, but you'll need to do the sensor linearization in the host microcontroller.

    Not sure what is meant by bootloader here?

    The modulator will reset each conversion after a single-event upset. The analog inputs can sink up to 15mA continuously so over-voltage protection can be done with a current limiting resistor along with a low-leakage TVS or similar.

    -Logan

  • Hi Logan,

    About the way to speed up by using two LTC2986s, how can I get 12ch in 1s since this part's ODR is 164ms typ in the two conversion cycle mode?

    About the bootloader, sorry I will check with our SW engineer.

    About taking measures for latch-up, LTC2983 and LTC2983 do not need such protection or do you recommend to prepare a current limiting resistor along with a low-leakage TVS?

    Regards,

    Kazu

  • Hi Logan,

     

    About the way to speed up by using two LTC2986s, how can I get 12ch in 1s since this part's ODR is 164ms typ in the two conversion cycle mode?

    I take back my question about the bootloader.

     

    Regards,

    Kazu