Good Morning,
I am looking at the MP4835A and it states that the Junction temp range is -25 C to +125 C.
What is this at ambient? Our application is -40C to 85C.
Thank you for your assistance.
Pierre Turcotte
You have to figure it out, if your ambient is 85C and the max junction is 125 then you are allowed a 40C increase over ambient. The junction to ambient rating of the package is 15C/W so 40c allowed increase and 15C/W means you can dissipate 40/15 or 2.66W in the device. So now I guess you have to go figure how many channels are in use at any time, what the currents are and therefore what the dissipation is.
If you slap a heat sink on the part or blow air on it then you effectively modify the 15C/W number and it can handle more power.
Thank you for your response. I am less concerned with the hot side of the part. We are more concerned with the cold. We are in some extreme areas.
Sort of hosed I would say. If the ambient is -40 and the part isn’t dissipating power like it has been off all night then the junction is at -40 as well. This issue is most likely to be parametric it will probably still “work” but thresholds will be different. You need an industrial version.
Hello @pierre.turcotte ,
Just to confirm, yes the ambient is something that you would determine. The junction temp range is the temp range that the part is OK to operate at. If you believe -25-85C is not enough for your application, we recommend looking into industrial solutions for a wider operating temp range.
Thank you for you patience and thank you jshannon for your assistance!
Regards,
Jonathan