MPX4250AP - am i reading datasheet wrong?

[andrew3]

Hi all,

Trying to build a project for myself and I'm using an MPX4250ap absolute pressure sensor

Here's the data sheet - (https://www.nxp.com/docs/en/data-sheet/MPX4250A.pdf)

I have a few of these sensors and they are all outputting the same voltage, so I believe maybe I'm incorrect in my understanding of how they work, maybe someone could help me out?

The sensors output .5v which according to that sheet is near 30kpa. I believe this is incorrect because I'm at sea level and the current pressure reported from the weather is 103kpa. So I would think that I would expect an output value of near 2v based on the figure #5 on page 5.

I'm using an arduino microcontroller and using the 5v VCC line (with caps) to power pin 3, grounded pin 2, and pin 1 is my output to a cap, then the analog pin on the arduino. I verified arduino senses the same as my meter.

I attempted to take just one of the sensors I haven't used yet and connected it to a 5v regulated bench supply and also had ~.5v output on pin1 (Vout)

Am I just incorrect in thinking I should be getting near 2v and .5v is the correct output?

[Volvo940]

I have the same sensor the MPX4250AP and get the same reading at sealevel. Is the sensor faulty?

[TomasVaverka]

Hi Andy,

Your understanding is correct, when using the MPX4250AP, it is expected to have about 2V on the output (at sea level, atmospheric pressure) as it measures with reference to the absolute vacuum sealed inside the reference chamber of the die during manufacturing.

What I would recommend to check is the complete marking found on the top side of the sensors? Is it indeed MPX4250AP and not MPX4250GP which is a positive gauge pressure sensor measuring the positive pressure relative to the ambient pressure on the P2 side?

Best regards,

Tomas