DCR010505: Isolated Power Modules and Digital Isolators at Altitude

Hello Robert,

Thank you for considering our products.  My understanding is at higher altitude the breakdown voltage of air is lower, but I need to check with our product engineer experts about this device.   

Before I contact our PE experts, may I ask if you read the Caution note box in the datasheet?  Please also read the feature description section.

If this still meets your requirement, could you tell what is your desired isolation strength?

Best Regards,

Youhao

Hi Youhao,

I read the caution notes. We have not determined the actual isolation voltage requirement. At this point, I am more concerned if this device, similar devices in this category and the digital isolators will function properly at altitude. Are the internal transformers or isolation affected at altitude (or other internal concerns)?

Thanks,

Bob

Hi Bob,

Understood your concern.  This is not a regular question which we apps engineer usually receive.  I have to ask our PE expert.  This may take some time but I will get back to you ASAP. 

Thanks,

Youhao

OK. Thanks.

Hi Bob,

Thank your for understanding, and please do not just reply due to courtesy because this will unnecessarily trigger the e2e timer by which we will have to respond in 24 hours.  Our team is looking into this and I will update when I get an answer, and it can take a couple of days.

Regards,

Youhao

Hi Robert,

I from the digital isolators product group and I can comment on your question related to digital isolators.

If the parts are conformal coated, then I believe creepage and clearance concerns are taken care. I am not sure if thermal concerns are completely addressed by the conformal coating, if it does take care of external temperatures and the device doesn't see those temperatures then I do not expect the device to have any thermal concerns.

Assuming there are space related radiations at this altitude, I do not expect the digital isolator to have any issues. Thanks.

Regards,
Koteshwar Rao

So, the isolation barrier internal to the device is not affected by the reduced dielectric at higher altitude, like a transformer air gap would be?

Hi Bob,

Our team is still looking into this.  Sorry for the delay and I will report ASAP.

Thanks,

Youhao

Hi Bob,

Our PE and quality experts did not find any isolation test being performed against the altitude of your interest. On the other hand, we have not heard of any issue of TI products in general being used in avionics with respect to high altitude. 

Our experts also gave a friendly reminder that at 55,000 feet altitude the ambient temperature would be -55C and this is obviously outside the device's recommended operating temperature range of -40C to +85C. It does not necessarily mean the circuit would stop working, but it may perform outside the EC-table spec limits. 

Regsards,

Youhao