TMP117： TMP117 temperature error issue

Huang yuohm

Part Number: TMP117

Hi ,all

I have two TMP117 (QFN Footprint) , I2C communication are OK , but they show the temperature value is more different even though int the same environment , one of them value is 26.1 ℃ ，another one value is 26.6 ℃ , what is the trouble of them ?

over 5 years ago

0 Josh Wyatt over 5 years ago

TI__Guru* 91206 points

Dear Huang -

Could you share the image of the layout? did you solder that bottom pad?

Can you review the "checklist" of items in Section 10 (starts on page 36) of the datasheet https://www.ti.com/lit/ds/symlink/tmp117.pdf and comment on any differences you might have implemented from these recommendations?

0 Huang yuohm over 5 years ago in reply to Josh Wyatt

Prodigy 140 points

that is my layout design , and circuit refer from official datasheet pages 35 . must not the thermal pad be solder ?

0 Ren Schackmann over 5 years ago in reply to Huang yuohm

TI__Mastermind 43995 points

Hi Huang,

What is the test environment? You will need a liquid bath to achieve better than about 0.5C uniformity. This is because air is a bad thermal conductor.

You may see variation due to mechanical stress of soldering if the devices are hand soldered, or if the guidelines are not followed. This mechanical stress should only cause errors less than 0.1C. The 0.5C variation you're reporting is likely from something else.

thanks,

ren

0 Huang yuohm over 5 years ago in reply to Ren Schackmann

Prodigy 140 points

There work in air by a small plastic bag now , The first chip value is 26.63 , the second chip value is 26.69 , and chip's register setting are reset default value , 1HZ 8 average .