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Pressure Measurement type pressure sensors

S

Spehro Pefhany

Jan 1, 1970
0

Absolute pressure sensors measure the pressure relative to an internal
vacuum reference. So, it will be close to 100kPA with the port open at
normal atmospheric pressure.

Differential type sensors measure the pressure on one port relative to
that on another port. So, it will read close to 0 kPA with both ports
open.

There are also sensors that have the second port
non-customer-connectable and left open to the atmosphere (gauge
pressure). They will also read close to 0kPA with the port open.

This is explained on page 2 of the data sheet.
if i use MPX2102A can i put Vout- to GND and read the output only from
Vout+ ?

No. Vout- is probably about half of the supply voltage. It's something
like a Wheatstone bridge internally, probably with some extra elements
for temperature compensation. You need a differential amplifier such
as an instrumentation amplifier to use this kind of pressure sensor.
There exist sensors with the circuitry built in, but of course they
are more expensive.


Best regards,
Spehro Pefhany
 
M

merco

Jan 1, 1970
0
thanks,

and what about interfacing it with a PIC16f88 with 10bit AD converter
with 2.048 vref, and 3.3V VCC supply ?
 
S

Spehro Pefhany

Jan 1, 1970
0
thanks,

and what about interfacing it with a PIC16f88 with 10bit AD converter
with 2.048 vref, and 3.3V VCC supply ?

Shouldn't be any major problems. You'll need an amplifier, as I
suggested.

Note that the output is ratiometric to the supply voltage for the
sensor, so it may not make sense to use two references, as that may
unnecessarily add two error terms. If you run the sensor from your
3.3V supply rather than the regulation 10V, you'll get 1/3 the output
voltage (about 13mV F.S.), which is not too bad with high performance
parts, given the 1%-ish accuracy of the part. Less self-heating as
well.


Best regards,
Spehro Pefhany
 
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