Precision local temperature sensing in a hermetic can
The LM35AH: It outputs 10 mV per degree Celsius, so a reading of 250 mV at the analog pin directly corresponds to 25°C without external scaling — the calibration is built into the silicon. The supply voltage can be anything from 4V to 30V, and the output is ratiometric to the die temperature, not the supply rail — so a noisy or drifting supply does not shift the reading.
The TO-46 metal can (TO-206AB, three-lead) is a through-hole package. The case itself is the thermal junction — in a still-air environment the self-heating error is about 0.2°C, but in moving air or when bonded to a surface with thermal epoxy, the case temperature tracks the target within a fraction of a degree. The metal tab is internally connected to ground, so no electrical isolation is needed if the mounting surface is at circuit common.