[time-nuts] Thermal Time Constant

[jimlux]

Brooke Clarke wrote:
> Hi Bruce:
> 
> If a square meter of Styrofoam is 1.5 deg C/W then a cubic inch would be 
> 39.37 * 39.37 * 1.5 or 2,325 deg C/W
> 
> The DS3231 dissipates about 1 mw when running.  I'm not sure how to come 
> up with an allowable temp increase, but suspect it's based on not 
> exceeding the max allowed operating temp.  But for this part the Temp 
> vs. freq curve is flattest at room temp so best to minimize the temp rise.
> So:  (1 deg C) / (0.001 W) = 1000 deg C/W, the same number you had.
> 
> That requires 185 g of Aluminum or about 69 cc volume or 4.25 cubic 
> inches.  That's a block about 1.62" on a side.
> 
> How does that look?
> 
>

you can also use U.S. R-values..  BTU/hr/ft^2/deg F.