I'm working with the TMP01 chip to regulate temperature using batteries as the power supply. I have setup the chip to operate as in Figure 15b on the datasheet where it will turn on a heating element when the low temperature setpoint is reached.
The device works perfectly for a while but then something happens to the temperature regulation where the temperature (which I monitored using a separate device) starts to run way up (at least 5-10 C over the setpoint) until fading (likely because the batteries run out of power). The log of the test is attached to this post. I have tried this with different batteries (6V lantern battery and a set of 4 D cells) and I observed the same temperature control followed by a temperature spike and complete loss of heating ability.
Does anyone have ideas as to why this would behave in such a manner? I suspect it has to do with the supply voltage dropping below the minimum supply voltage (about 4.1V) but I don't understand why it would cause the heater to turn on.
Thanks for your comments.