LM35 temperature equation?

Hey guys,

I found this link about the LM35 sensor. The link explained how to get the equation but I still don't get it. So, someone please explain to me how the equation comes. I don't understand how why the 100 is there in the equation. Let say for example the room temperature is 19 degrees. How do you apply this equation.

Equation to get temperature using LM35: temp = (5.0 * analogRead(tempPin) * 100.0) / 1024
Link: Arduino Playground - LM35HigherResolution

Thanks.

Also one more thing I found about the sensor says that " No matter what supply you use, the analog voltage reading will range from about 0V (ground) to about 1.75V." for LM35. I would like to know why that is if anyone knows.

This can be found at Temperature sensor tutorial - Using the TMP36 / LM35.

thanks

two different sensors LM35 and tmp36 - have you read the datasheets...

yaantey:
Also one more thing I found about the sensor says that " No matter what supply you use, the analog voltage reading will range from about 0V (ground) to about 1.75V." for LM35. I would like to know why that is if anyone knows.

1.75v = 1750 mV = 175°C The LM35 is only good to 150°C so outputs above 1.5V (1500 mV) can't be relied on.

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The sensor has 100 degrees per volt of output so of course you read voltage and multiply by that factor to get degree.

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