HDC2080: HDC2080 - wrong humidity

German Kirillov

Part Number: HDC2080

Hi All,

I get right temperature from HDC2080, but humidity is very low. From 15% to 26% for real humidity 67% (measured by psychrometer with two thermometers).

I wait several days after soldering - no change.

If I make 100% humidity near sensor (drop of water directly to sensor window) - I get 80%-90%.

And after I remove water from sensor during 10 minutes I get again 26%.

over 6 years ago

0 German Kirillov over 6 years ago

Prodigy 75 points

I tried to use 3 pieces HDC2080. Result is the same.

0 Josh Wyatt over 6 years ago in reply to German Kirillov

TI__Guru* 91206 points

Dear German -

Did you follow the bake and re-hydration procedure after reflow - found in Section 11 of the datasheet? Page 30, link here:

0 German Kirillov over 6 years ago in reply to Josh Wyatt

Prodigy 75 points

I made drying not so big time. Only about 30 minutes, hot air 120 C.
But re-hydration - it is my room conditions - every day and night - +23C and 60..70% of humidity.
First IC works two weeks, another ICs - only two days.

0 German Kirillov over 6 years ago in reply to German Kirillov

Prodigy 75 points

Ok,

I made:

1. 10 hours - 102 C.

2. 24 hour - humidity 57%..67%, temperature 23...24.5 C.

Now I have temperature 24 C, humidity 60% in my room.

I read from sensor every 10 seconds :

Temperature 23.7 (0x62F3, 0x62F5, 0x62F2...)

Humidity 19.5% .. 20.9% (0x320B 0x33BF,0x359A...)

0 Josh Wyatt over 6 years ago in reply to German Kirillov

TI__Guru* 91206 points

German -
OK - seems like you are in the right direction of the procedure - but it seems you still have an issue, since you expect a value around 0x999A or 0x9999. (which would give you 60% RH) - since using the offset register (bit 7 register 0x09) would not put you that far off, nor would using the other 7 bits in that register bring you up high enough - perhaps you have damaged the sensor somehow through handling - can you give any detail about any the solder profile or cleaning you are using/doing?

Please ensure that you have also followed: www.ti.com/.../snia025.pdf

0 German Kirillov over 6 years ago in reply to Josh Wyatt

Prodigy 75 points

I soldered one chip with hot air, and other two with soldering iron. No different.

I did not used cleaning.

I measured humidity outside of my room. Wheather forecasters said humidity is 49%, temperature is -2 C.

And HDC2080 during 30 minutes crawled from 18 to 42%. I measured the humidity at the 6th floor above ground with good wind, so the humidity is slightly lower than expected.

Now I think that my psyсhrometer is wrong. It is impossible, but it's fact.

0 Josh Wyatt over 6 years ago in reply to German Kirillov

TI__Guru* 91206 points

German -
From your description - it makes sense what you describe as device behavior after you subjected them to hot air or a soldering iron.

We do not recommend using hot air or hand soldering with these devices.

As mentioned in the datasheet - IR reflow with a controlled profile is recommended and the bottom pad must be soldered as well. Please see and follow if possible Sections 11.1.1.2 through 11.1.1.5 (page 30) www.ti.com/.../hdc2080.pdf

0 German Kirillov over 6 years ago in reply to Josh Wyatt

Prodigy 75 points

Thanks, Josh

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HDC2080: HDC2080 - wrong humidity