486DX4 thermal management questions

[TMcTa]

We are upgrading a legacy embedded system and think we have thermal issues. the Intel 486DX4 (mounted on a PC104 board) runs much hotter than its max rated case temp of 85C and the system shuts down. The data sheet lists only max case temp (85C), but no junction temp. The data sheet values for theta jA and jC seem to imply that the max juncition temp might be as low as 90C, though this is not specified. Coming from an embedded background in which max tJ is commonly specified, I have some questions for those who are more conversant with PC type CPUs:

1. what is a likley max tJ for the Intel 486DX4?

2. (why) is it lower than typical max tJ of 125C for embedded devices?

3. does the 486DX4 have any temperature-sensing shutdown mechanism (I have not seen anything like this in its literature, but I gather that newer CPUs may have it...

Thanks in advance for any comments on this!

[Adolfo_S_Intel2]

Currently we no longer have information on those processors since they are too old.

In this particular case I would suggest contacting a Field Application Engineer (FAE) so he / she can provide you that information.

In order to contact a Field Application Engineer (FAE), you need to call an Authorized Intel® Distributor at:

http://www.intel.com/cd/channel/reseller/asmo-na/eng/227304.htm http://www.intel.com/cd/channel/reseller/asmo-na/eng/227304.htm

If you are in a different location please check this link:

http://premierlocator.intel.com/Default.aspx http://premierlocator.intel.com/Default.aspx