HDC1080: Humidity sensor %RH reading variance vs EVM

Leo Chow

Part Number: HDC1080

Hi,

one of my client is currently using HDC1080 sensor on their test to read out humidity in a closed environment. During design tape out, pin-7 was left floating as per datasheet guideline whereas pin-7 was connected to GND on the EVM. Will this affect the accuracy of sensor in reading RH levels?

the issue that showed up was the accuracy of %RH reading; upon inspection the HDC1080 on customer board is labeled as 741R & reading differed up to 15%RH vs EVM. Next we performed AB swap on humidity sensor (carrying datecode of 821R) & the outcome tallies with what we're reading on EVM. Are there any calibration required which we may have missed out that may caused the issue mentioned? Please advise.

Regards,

Leo

over 6 years ago

0 Ren Schackmann over 6 years ago

TI__Mastermind 43805 points

Hi Leo,

The electrical connection at the thermal pad does not affect the humidity reading.

Are you saying that the error followed the board and not the device?

Thanks,
Ren

0 Leo Chow over 6 years ago in reply to Ren Schackmann

TI__Expert 3120 points

Hi Ren,
okay then we shall rule out the condition of Pin-7 then. The error followed the device, not board. When i mentioned AB swap it's device level. Swap from (DC 821R device to DC 741R) device.

Regards,
Leo

0 Ren Schackmann over 6 years ago in reply to Leo Chow

TI__Mastermind 43805 points

Leo,

If you are seeing your devices gain a positive offset, your solder process may be damaging the humidity transducer. The transducer is a polymer applied to the top of the silicon IC and exposed by the opening in the plastic packaging. This polymer can't be submerged in water or cleaning solutions, because it will absorb moisture that permanently alters its behavior.

Thanks,
Ren

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HDC1080: Humidity sensor %RH reading variance vs EVM