AD2S44-TM12B

Dear support team,

We have bought two AD2S44-TM12B chips in order to measure the angle of our device. we connected two sychros reference terminals of the chip with 36 VAC, 400Hz and the signal terminals with three phase about 56 VAC. The chip got a little bit warm and give us errors. We checked the datasheet and recognized that the standard synchros reference terminal of the chip is 115 VAC 400Hz and the signal terminal around 90 V rmc. We don't know how to solve this problem. If you can, please let's know.
Thanks for your help
Parents
  • 0
    •  Analog Employees 
    •  Super User 
    on Nov 6, 2019 2:24 AM

    Anh_Ho,

    Can you please provide a schematic or reference drawing for how you have configured the system to that I can best determine how to help you resolve this issue?

    Sean

  • Hi Sean, 

    Thanks for support

    anh here is our scheme. If you have any questions, please don’t hesitate 

  • 0
    •  Analog Employees 
    •  Super User 
    on Nov 11, 2019 1:37 PM in reply to Anh_Ho

    Anh,

    Assuming your drawing is complete you may want to add the recommended supply decoupling to the +VS and -VS supplies from page 7 of the datasheet as it is possible that power supply noise is disturbing the loop and tripping the error state.

    Additionally, where you are not using channel B you may want to put a weak pull-up resistor to the logic supply of the uC to ensure only channel A is ever selected...at least until you get your setup working.   My thinking here is that it could be possible that the fault is related to detecting no input on channel B.    To be safe you could try tying S1-S4(B), RHI and RLO(B) to ground to ensure the voltages at those nodes are in a known state.

    Sean

Reply
  • 0
    •  Analog Employees 
    •  Super User 
    on Nov 11, 2019 1:37 PM in reply to Anh_Ho

    Anh,

    Assuming your drawing is complete you may want to add the recommended supply decoupling to the +VS and -VS supplies from page 7 of the datasheet as it is possible that power supply noise is disturbing the loop and tripping the error state.

    Additionally, where you are not using channel B you may want to put a weak pull-up resistor to the logic supply of the uC to ensure only channel A is ever selected...at least until you get your setup working.   My thinking here is that it could be possible that the fault is related to detecting no input on channel B.    To be safe you could try tying S1-S4(B), RHI and RLO(B) to ground to ensure the voltages at those nodes are in a known state.

    Sean

Children
  • Thanks Sean. I am going to try your solution, and give you feedback soon

  • Hi Sea, 

    Other thing is we still wonder if the chip can work with 36VAC 400Hz for reference terminals and 56V rms for signal terminals.

  • according to DataSheet "A feature of these converters is that the signal and reference inputs
    can be resistively scaled to accommodate nonstandard input signal
    and reference voltages that are outside the nominal ±10% limits of
    the converter" therefore, do we need a transformer to gain our 36VAC to 115 VAC for the chip?

  • 0
    •  Analog Employees 
    •  Super User 
    on Nov 13, 2019 1:46 PM in reply to Anh_Ho

    Ahn,

    I've reached out to a colleague who has more familiarity with this product than I do to assist you with your specific question.   I hope he will be able to answer your question directly.

  • 0
    •  Analog Employees 
    on Nov 13, 2019 3:47 PM in reply to @skowalik

    Hello Anh_Ho.

    Is it possible to use a standard syncro for your application that is rated for the 90V signal and 115V reference?

    The Reference voltage will need to be within 10% of the rated value. Correct, for the AD2S44-TM12 Synchro converter, the reference voltage to the converter will need to be 115V +/-10%. Since your reference signal is only 36V you will need to step that up to 115VAC. 

    Additionally your 3 Wire Synchro Signal of 56V should be OK once you get the reference straightened out. You will just have to take that signal difference into account when looking at the digital outputs. I'm not sure if the Built in Test (BIT) pin will be provide any functinality since the input signal is so low compared to the expected. 

    You will also need to put the recommended parallel combination of  decoupling capacitors on both supplies. Typically we recommend a 100nF in parallel with a 6.8uF Tantalum on each supply as close to the AD2S44 as possible. 

    This converter has a resistive front end to the converter that will allow for scaling the synchro signals and reference signals but this is only valid if the signal provided is greater than the rated voltages. In your case this will not work.