LM35 temperature sensing limits

what is the maximum temperature that LM35 sensor can sense ? According to its specification it can measure upto 150 degree Celsius, but in my case it stucks at exactly 100 degrees. Can anyone explain why ?

it is probably because it is not very sensitive after 100 degree celsius and thus it is set up to measure only till 100 degree celsius.

Here’s an image from the datasheet:
lm35
I guess you should go for circuit 2.

Also examples (pretty complex tho) are given at page 16 of the datasheet

Datasheet : http://www.ti.com/lit/ds/symlink/lm35.pdf

Also, can you show the conversion code you used for voltage to temperature?

hello @jazib980 !
I will try your suggestion and let you know if it works.
I have used following conversion formula-
T °C = sensor value/ 10.24.
I think the problem is because, bolt can read upto 10 bit data through analog read, and max. value in this is 2^10 = 1024. And at 100°C sensor value is also 1024.

Hey @ravi_verma, you’re right.
Here’s what I found in the docs: https://docs.boltiot.com/docs/bolt-wifi-module

ADC : 1 pin 10 bit ADC [0-1V input]

The Lm35 has 0.01V/ °C so at 100°C it gives 0.01*100 = 1V which is the max it can measure.
Since Lm35 is calibrated even connecting to a lower voltage won’t help.

So Bolt microcontroller is restricting us to use LM35 at it’s full potential.:laughing:

1 Like

yes the limit is from -55 to 150 degree but if its giving error try contacting the bolt support at support@boltiot.com either they will replace the sensor or provide the solution.

Yup and you probably shouldn’t try to light these components on fire, seriously what are you subjecting these poor microcontrollers to

no bro I’m not subjecting these components on fire.:sweat_smile::sweat_smile: I’m just subjecting the temperature sensor only to high temperature because according to its specification it can bear that tempreture levels. by the way, i had placed the sensor just near the coil of hot air blower.

1 Like