[strange problem] ADT75 temperature sensor on i2c


I have a strange problem. I am reading two ADT75 via i2c, but ONE of the sensors fails on temperatures above approx. 34°C.

These guys are very small surface mounted chips, so in I soldered them with tiny copper wires on some small stripe-board. One is on address 0x048 the other one on 0x049 (Pin 7 (A0) connected to VDD). The other address pins are open.

I tested several values for Pull-up resistors. No change.

So did I killed one while soldering? DId someone encountered similar problems (even on other i2c devices)? Any other ideas?

Best regards, Carsten

HI Carsten,

what happens if you only connect the “failing” one does it show the same behaviour?

Do you have a link to the datasheet of teh ADT75? there might be a reset command? never give up hope :slight_smile:

Given your sensor is this one: www.analog.com/static/imported-files/data_sheets/ADT75.pdf, you have to solder the address pins that are not on Vcc to GND. A floating pin (not connected) may switch to high, maybe that could be driven even by a higher temperature.

Oh! Good advice. I try that.

Sorry for the late reply, notify was not on.