ADT6401 Output Problem

Question

Hi, 
 We are using two ADT6401 temperature switches on our board. They are open-drain output. We use one for the high temperature (+85 degrees celcius) and one for the low temperature (-45 degrees celcius). Our schematic is attached. 
 Temperature switches can shutdown our board. While we are testing the board at room temperature, our board shuts down because one of the temperature switches pulls their output low. We could not understand which of them. But the temperature is very far away from both high and low limits. So temperature switches do not operate correctly, that's for sure. 
 Our low temp. switch inputs are Float - GND - Float. If the float on the S2 pin, is measured as GND some time, the temperature setting goes to +65 degrees celcius. Could this be a problem? Or could it be a soldering effect? 
 Thanks, 
 Celil

ADIApproved · Accepted Answer

Hi, apologies for delay in getting back. We have looked at ADT6401 on the bench and when the rise time is >10mS from 0->2.7V, the part isn’t entering the correct mode with the associated floating inputs. 
 We also tied the S2 & S0 pins to Vdd/2 but to no avail as part interprets the pins as a high. 
 The next nearest family is ADT6501, these have factory set trip points in a similar SOT23 package.)

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ADT6401 Output Problem