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ISOW1412: CISPR32 use vs MIL-STD-461E for ISOW1412 device

Mynard Pentz
Prodigy 30 points
Part Number: ISOW1412

To whom it may concern

the datasheet for the ISOW1412 describes the inclusion of a number of capacitors around the device connected to the power pins. However, these capacitors make it only possible for the part to attain noise levels that conform to CISPR 32.

1. We would like to achieve MIL-STD-461E conformance for this device in terms of electromagnetic compatibility. Is this just a matter of increasing the capacitors around the transceiver, or is there more than meets the eye? What would be required?

2. Furthermore, is there a way of figuring what the noise levels would be when the receiving antenna were positioned 1 meter from the UUT, instead of the 3 meters specified by CISPR32?

3. Are any measurement result available of how the device performs EMI-wise without any decoupling at all?

I basically need to know how much of an effort it would be to get the device to perform to MIL-STD-461E levels, specifically RE102 most stringent case.

 Please refer to document SLLSF22G dated June 2022.

Thank you very much

Meyns

  • 0
    TI__Mastermind 21505 points

    Hello Meyns, 

    Thank you for reaching out. 

    1. We are unfamiliar with MIL-STD-461E and cannot make any recommendations since this is not an end equipment standard we test for.  It is up to the manufacturer to test for standards further than what TI's certifies.  
      1. In terms of how much effort it would require to meet MIL-STD-461E mil levels, I cannot say. I would try to follow the CISPR32 recommendations and see if it passes MIL-STD-461E.However, without specific information on how/if this device isn't passing, we can't provide specific recommendations. 
    2. I believe this can be calculated by referring to "Free-space path loss" equations. 
    3. We do not have this information publicly available. 

    Best,
    Andrew

  • 0 in reply to Andrew Jackiw
    Prodigy 30 points

    Hello Andrew
    Thank you for replying.
    From what I could figure out myself is that to attain MIL-STD-461E acceptability would need an improvement of some 25dB of additional noise attenuation. That is based just on my own observation of the requirements specified in M-461E and a table that was published in an article by David Hoolihan. The difference is large, I have to admit.

    Would the information of point3 be available by NDA or was the device not characterised at all?

    Thank you very much

    Meyns

  • 0 in reply to Mynard Pentz
    TI__Mastermind 21505 points

    Hello Mynard,

    You have probably seen these app notes, however I would like to link them just in case. Since they apply:

    From some research, it looks like since ISOW1412 meets CISPR 32 Class B limits it will likely meet MIL-STD-461E, however I cannot confirm this. 

    As for CISPR32 data under a "no load" condition, I believe that the worst case is considered to be the 100mA load. Therefore, a no-load condition would likely improve results. Regardless, I do not believe this data was characterized so an NDA would not help here. 

    Best,
    Andrew