Hello,
I am considering using the SM320F2812-HT for an R&D manufacturing application that will require it to withstand a heating cycle taking approximately 2-3 hours from 25C to 180C, and then holding at 180C ambient for 4 hours, about two times a week for several years. I am trying to estimate the lifetime in hours on the datasheet, but cannot find a thermal resistance for junction-to-ambient.
We plan on running on the lowest available frequency (which appears to be 2MHz) and will be logging data at a generally slow rate (2Hz data sampling) from about 14 ADCs at a time. It will send this through a serial interface to a computer outside the 180C ambient chamber. The datasheet seems to suggest (p.88) that the typical current draw for our application will be about 200mW, is this correct?
That being said, I now want to find an estimated temperature for the junction based on power dissipation, but I don't see any thermal resistance value in C/W listed on the datasheet and was wondering if it is possible that you have a number for that. This way we can estimate the average lifetime in hours of our chip.
On another hand I would mention that we are also considering the SM470R1B1MHFQS instead, perhaps you have a recommendation on which to use. However, the 64 pin version of this chip seems to have a really high thermal resistance and at 180C my calculations with 225mW dissipation (from your quote on junction-to-board resistance) implies the junction will on average be consistently over 215C and the operating life will be less than 100 hours.
Thanks in advance for your help!
Theo
