LM35 Temperature sensor getting too hot! - Page 1
Forum section: electronics / general

author: Mint.
author_rank: Frequent Contributor
timestamp: May 26, 2012, 01:25:01 am
content: So I bought a two LM35 temperature sensors off eBay to do this project:http://embedded-lab.com/blog/?p=4951I decided to see how it worked so I hooked the thing up to 5v and after 10 seconds the device got really hot! The sensor was outputting 2.2v max before I switched it off. Thats not supposed to be like that right?I decided to hook it up to 9v next, it was a little bit less warmer at first, but then it started to heat up also. The sensor was outputting 1.2v max before I switched it off.Did I ruin my sensor?What am I doing wrong here?

author: IanB
author_rank: Super Contributor
timestamp: May 26, 2012, 01:31:03 am
content: If you are sure you are connecting power to the right pins then the device must be faulty. What assurance do you have that it is a real and genuine part?

author: Mint.
author_rank: Frequent Contributor
timestamp: May 26, 2012, 01:39:21 am
content: Quote from: IanB on May 26, 2012, 01:31:03 amNoneI guess I'll take the risk to switch the two pins around to see if it works.

author: Mint.
author_rank: Frequent Contributor
timestamp: May 26, 2012, 01:42:35 am
content: Whoops! It worked, sorry for my ignorance

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: May 26, 2012, 06:30:13 am
content: Quote from: Mint. on May 26, 2012, 01:39:21 amPerhaps taking time to look at the data sheet would have been a good idea?

author: TriodeTiger
author_rank: Regular Contributor
timestamp: May 26, 2012, 06:59:00 am
content: Quote from: Jon Chandler on May 26, 2012, 06:30:13 amHe wouldn't have learned from this neat experiment, and may forget the consequences of even low power devices and how they can smoulder when mistreated.

author: Mint.
author_rank: Frequent Contributor
timestamp: May 26, 2012, 08:10:54 am
content: Quote from: Jon Chandler on May 26, 2012, 06:30:13 amI did get a data sheet from the seller, but it was incorrect. So thats why I decided to ask around...

author: amyk
author_rank: Super Contributor
timestamp: May 26, 2012, 11:26:58 am
content: Did it match the official datasheet?http://www.ti.com/lit/gpn/lm35I've seen some off-brand transistors (like '13009s) that had different pinouts to the "genuine" parts.

author: TriodeTiger
author_rank: Regular Contributor
timestamp: May 27, 2012, 12:03:03 am
content: Quote from: Mint. on May 26, 2012, 08:10:54 amThis could serve a purpose in learning as well, there are too many sites (not the big guys) that link to outdated, incorrect (by revision or number) or dead links.A quick search of LM35 should bring up the top manufacturers and the accurate datasheets, you can always download these on to a folder for further reference now that you know "it really is for my device."

author: lasmart613
author_rank: Newbie
timestamp: February 19, 2016, 06:48:55 pm
content: I also had the same problem. Double-checked, triple-checked datasheet. Did Google search on the problem and found this thread. I switch the +V and GND terminals and it worked great. The datasheet is wrong on the pinout for the TO-92 package.Even though the device got hot, it still worked when I switched the leads.

author: Zero999
author_rank: Super Contributor
timestamp: February 19, 2016, 08:47:33 pm
content: Another possibility is you got a fake/reject with the connections reversed. I've bought LEDs before with the anode and cathode backwards.