# Confused on a basic convention

I'm really new to any circuitry and electrical stuff... just got started with Arduino this week. I'm reading a datasheet for a temp sensor and can't understand all of the variables.

http://www.analog.com/media/en/technical-documentation/data-sheets/TMP35_36_37.pdf

This sheet on page three in the test conditions/comments section repeatedly refers to $T_A$. What is that, temperature average or something?

I've scoured around but it's a pretty specific thing to search for. Does anyone know the best way to learn about these types of variables/abbreviations, or is it just expected that you're going to figure it out and know what this stuff means? I know datasheets are written for engineers by engineers but that makes a high bar for entry for those of us without the necessary tribal knowledge.

There are other things in there too -- $I_l$, $V_s$, etc. While I understand the primary variable the subset throws me off. I imagine there are a set of basic ones that I just need to learn...

• Without looking at the datasheet I would say it is an ambient temperature... Update : After looking at it I won't change my mind. – Eugene Sh. Oct 11 '17 at 16:21
• @Eugene Sh. Would you say then that the first entry in that table is saying that at 25deg C ambient temperature you will see typical variance of +/- 1deg C? Seems reasonable. Also, do you just "know" that from experience or is there a way for me to learn this stuff better? – dudewad Oct 11 '17 at 16:24
• Yup as @EugeneSh. states its ambient temperature.. or more precisely the temperature of the air surrounding and contacting the device package. – Trevor_G Oct 11 '17 at 16:24
• $T_A$ Ambient temperature (temperature of the environment). $T_C$ Temperature of case. $T_J$ Temp of semiconductor junction. You might benefit from a search for "Thermal management (electronics)". – glen_geek Oct 11 '17 at 16:26
• @Trevor +-2c is indeed a ton but its the crappy little temp sensor that came with the arduino starter kit... I'm just using this as a foray into understanding the world of electronics. When I feel like I'm able to build circuitry without frying my components I'll start buying actual, useful sensors :P – dudewad Oct 11 '17 at 17:01