RθJA (thermal resistance, junction-to-ambient) value required for intrisic safety certification

[Amarotica]

Hey there, we are currently going through regulatory testing for a hazloc product. Our product includes an nRF52805 which is used for BLE provisioning and debugging of the system. Our certification partner requires the RθJA value for the nRF52805 IC to continue with certification.

We have been unable to find the RθJA in Nordic's documentation - are we overlooking something?

To be clear, it is quite obvious that this IC shouldn't have thermal issues/safety issues, but intrisic safety certifications are extremely strict and need the actual data nonetheless.

Thanks in advance!

[Asbjørn]

Hi Taylor,

I'm awaiting feedback if we have numbers on this available. I'm guessing you've seen the numbers for the nRF52840. The numbers will be in the same range with the nRF52805 as it is using the same QFN/CSP package, but the actual details for nRF52805 we need to wait for.

Best regards

Asbjørn

[Amarotica]

Thank you Asbjørn , that is some great info that we've now forwarded to our certification partner as initial/interim information. They are still looking for the nRF52805 numbers, so I'm looking forward to when you get those details back.

Best,

Taylor

[Asbjørn]

Hello Taylor,

We can't share the report itself as it's a product of our package vendor.

For the QFN version of the nRF52805 we have thermal junction number (RθJA) at 27.01°C/W.

For the WLCSP we haven't got a specific number for the nRF52805, but for the nRF52832, which is slightly larger. So the nRF52832 has a junction number at 40.86°C/W. For the nRF52805 WLCSP the number will be slightly higher, estimated around 45°C/W. 

Best regards

Asbjørn

[Amarotica]

Thank you Asbjørn this is great info! I've passed it along to our testing partners and will ping back here if we have any more questions.

[jk1]

 Asbjørn I'm in the exact same boat. Any chance you guys can get the nRF52805 WLCSP °C/W number and can add that to the product specification?  

And the irony is if it even said 200°C/W we'd be pass, since there's no way this will fail compared to other items!  But without just about *any* number it's a no go.