Re: LM92 temp problems - again


seegoon99@xxxxxxxxx wrote:
Hi there.
Both LM92's are running from 5V. That's about 1.75mW or 0.35 deg C rise
in temp.
The difference I'm seeing is 2.5 deg C. That's a big difference.
Still stumped:0(
Cheers
Rob

Hmm, the LM92 accuracy spec at +5v is -0.13/+.53 degrees C, so 2.5
degrees difference _is_ more than the maximum 0.53-(-0.13)=0.66 deg. C
expected.

1) Are the parts really measuring the same temperature? Try making
sure by clamping both to one big bar of copper or aluminum, the whole
covered in bubble-wrap or some such to protect from air currents.

2) Digital output loading: if high, could cause self-heating.

3) Are both active and inactive for equal amounts of time? That
could produce differential heating. While active the LM92 draws
0.35-0.63mA; inactive the parts draw <5uA.

Cheers,
James Arthur

.

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