We have a question regarding the Auto-Zero function that can reduce the offset of pressure sensors.
Currently, we are checking whether auto-zero would be a suitable way to our application. For this I need to explain a little about our system:
We have created a control unit of a cooling product that has two main functions: (1) controlling a pump by a button press; and (2) logging sensor data on an SD card (two of the five sensors are freescale pressure sensors: MP3V5010DP and MP3V5004DP). This control unit is continuously ON, from the moment that the system is installed at the customer’s house to years after. The control unit will be standing nearly at the same place.
We read that an application that lends itself for auto zero experiences a zero-pressure condition at system start up. It is no problem to have a moment of zero pressure at system startup, but since the startup is only once in maybe 5 or 10 years, I’m wondering if the offset isn’t changing over time? After startup there will always be pressure on the sensor so at startup is the only option. What we’ve seen with the sensors at our office, is that over time/place the offset of the sensor is also fluctuating.
Could you advise us on whether the auto-zero function would be a solution for us?
Thank you!
Lia Bardoel
Hello Lia,
Thank you very much for writing.
I highly recommend to implement Auto-Zero routinely. In this way, the accuracy of the device would be highly improved over time.
AN1636: Implementing Auto-Zero for Integrated Pressure Sensors
http://www.freescale.com/files/sensors/doc/app_note/AN1636.pdf
The main error contributor in any application were pressure sensors are used is the offset and the easiest and most efficient way to avoid this error it's Auto-Zero.
I hope this information helps.
Best regards,
David
I have the same problem in HVAC application.
we've seen 100mV of offset variation over time. It's 30% of my FS.
what variation you found?
Tank you.