0
\$\begingroup\$

The differential ADC on my circuit has 1 channel open, and I decided that to place a temperature sensor IC. The temperature IC is LMT70. According to the output voltage table from the datasheet, the output voltage in relation to the temperature are:

enter image description here

My uncertainty comes from that the table shown is for a 2.7V supply, and I can only provide 3.0V (same as the ADC's supply.)

Would this table still hold true even for a 3.0V supply? The ADC uses an internal 1.2V reference and although that 1.2V on this table is -20 degrees Celsius a situation where my circuit will most likely not be exposed to im worried that the 1.2V Vtao of 3.0V supply would creep to the 20 degree Celsius where the circuit will be exposed to.

Simplified circuit:

enter image description here

I would hope that I won't have to use a voltage divider to lower the output to not waste the accuracy of the IC.

\$\endgroup\$
0
1
\$\begingroup\$

I don't think the output voltage changes much with supply voltage variations. For instance, look at this figure for the output voltage at 30 °C versus supply voltage change. I've added vertical lines for supplies of 2.7 volts and 3.3 volts: -

enter image description here

BTW your schematic is incorrect: -

enter image description here

\$\endgroup\$
4
  • \$\begingroup\$ Sorry about the decoupling I made a mistake there. \$\endgroup\$
    – Jake quin
    Nov 22 '20 at 18:10
  • \$\begingroup\$ Do you think some sort of calibration is needed per board with this IC ? The table gives values in the microvolt (which my adc can theoretically handle) so a slight change in supply voltage might offset the reading. Im already having a hard time thinking of how to get an accurate temperature controlled room to get the readings from >.< \$\endgroup\$
    – Jake quin
    Nov 22 '20 at 18:14
  • \$\begingroup\$ Though i dont think i need it to be that accurate since this is just a filler component, ill just have to assume that they are the same. Thank you good sir. \$\endgroup\$
    – Jake quin
    Nov 22 '20 at 18:16
  • \$\begingroup\$ I think if you can get hold of a decent thermocouple sensor then a spot check at a couple of temperatures will be useful as a check. \$\endgroup\$
    – Andy aka
    Nov 22 '20 at 18:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.