Teensy 4.0 results in small enclosure

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analog&RFmodels

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spacing in final post not what i had after pasting text in - not sure how to prevent that
maybe i should attach a text file next time


FYI - here are some results for T4 in a small sealed plastic box.

Results are good even down to 4 cubic inches.

tamb = 26-27 c, 1 hour soak, ir thermometer w 0.1 inch target dia

all below: t4 running at 816 mhz fed w 5.0 volts

situation iq top center cpu tempmon

horizontal with small air flow ceiling fan 133 ma 48 c 61 c

horizontal still air 139 ma 61 c 75 c

inside sealed plastic box 4 cubic inch 143 ma 72 c 87 c
top center box outside surf at 39 c
816 is not usable but 720 is

4 cubic inch box was 0.66 x 2.10 x 2.90 inch medium hardness
plastic with 0.050 inch wall thickness.

Although the tempco of iq is positive, there is not enough gain
for a runaway (gain seems to be about 0.2).

The variance with volume/surface area was small - 5 deg c
improvement when vol increased to 11 cubic inch plastic.

The variance with material was small - 7 deg c improvement
when box matl 0.032 aluminum.

Versus clock in 4 cubic inch plastic box, amb = 26-27 c, still
air, box horizontal on plastic spacers, all numbers from
tempmon (limit is 90 c):

Code:
  clock   no box    with box  allow amb c  allow amb f

   396     50 c       58 c            58           136
   528     54 c       61 c            55           131
   600     60 c       67 c            49           120
   720     67 c       78 c            38           100
   816     76 c       87 c            29            84  nil margin

Outdoor:
Direct sunlight on the box will subtract 10-30 deg f from the
allow amb numbers. Here where I am, in the summer, 396 would
be borderline so for outdoor use it would be best to provide
a decent, short conduction path between the chip top surface
and the inside wall of an aluminum box.

Variance was +- 0.7 deg c from run to run and about +- 2 T4 to
T4 giving an rss of +- 2.1 deg c.

defragster edit: { added # / CODE block around table - that preserves some spacing elements }
 
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