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> New pressure sensor, silicon transducer, 0-300MM hg rel
New pressure sensor, silicon transducer, 0-300MM hg rel
Motorola Part MPX2301DT1 (now Freescale Semiconductor)
You connect a flexible tube to the sensor's inlet port, and it measures the pressure in the tube. A hermetic gel protects the semiconductor wafer from contaminants in the medium to be measured.
RELATIVE measurement: senses the pressure on the nozzle side of the device relative to the pressure on the back of the silicon chip.
So if you were to seal off the nozzle with a non-flexible plug, device would sense the pressure behind the chip as an absolute measurement, (having as baseline the ambient pressure at the moment the nozzele was plugged.)
Hookup is, (from left): VCC, Out+, Out-, GND.
You can find application info on the web.
All pressure sensors are essentially a Wheatstone Bridge on a silicon wafer, see below
http:// /HowPage004.html
You apply a clean DC voltage at the top and bottom nodes of the bridge, and you measure the differential voltage at the remaining 2 middle nodes. Best done by feeding these to the +/- inputs of an opamp or instrumentation (differential) amp.
A typical application (for a different sensor, pinout has different order, but same connections)
http:// /pic/files/altim1c.gif
If you look at all application schematics ( many are for rocket altimeters, by hobbyists) you see a common denominator: 2 pins to a DC voltage, 2 pins to an op-amp's differential inputs.
NB. Avoid using any schematic that mentions the Motorola MPX4xxx or 5xxx series, as these are Absolute pressure sensors, and have different pin assignments, different implementation.
NOTE: The silicon die and gold wire bonds are exposed on the back of the device. Application mounting must ensure mechanical protection from this side. Simply mounting the part flat on a PCB, as in the top photo will provide that protection.
