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TMP01 battery operation

Question asked by dw2600 on Aug 18, 2014
Latest reply on Aug 18, 2014 by harryh

Hi,

 

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.

140818_D_battery_entire_test.jpg.

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