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SEMICONDUCTOR APPLICATION NOTE
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Liquid Level Control Using a
Motorola Pressure Sensor
Prepared by: JC Hamelain
Toulouse Pressure Sensor Laboratory
Semiconductor Products Sector, Toulouse, France
Motorola Discrete Products provides a complete solution
for designing a low cost system for direct and accurate liquid
level control using an ac powered pump or solenoid valve.
This circuit approach which exclusively uses Motorola
semiconductor parts, incorporates a piezoresistive pressure
sensor with on–chip temperature compensation and a new
solid–state relay with an integrated power triac, to drive
directly the liquid level control equipment from the domestic
110/220 V 50/60 Hz ac main power line.
PRESSURE SENSOR DESCRIPTION
The MPXM2000 Series pressure sensor integrates
on–chip, laser–trimmed resistors for offset calibration and
temperature compensation. The pressure sensitive element
is a patented, single piezoresistive implant which replaces the
four resistor Wheatstone bridge traditionally used by most
pressure sensor manufacturers.
MPAK AXIAL PORT
Depending on the application and pressure range, the sensor
may be chosen from the following portfolio. For this application
the MPXM2010GS was selected.
Device Pressure Range Application Sensitivity*
MPXM2010GS 0 to 10 kPa
MPXM2053GS 0 to 50 kPa
MPXM2102GS 0 to 100 kPa
MPXM2202GS 0 to 200 kPa
* after proper gain adjustment
± 0.01 kPa (1 mm H2O)
± 0.05 kPa (5 mm H2O)
± 0.1 kPa (10 mm H2O)
± 0.2 kPa (20 mm H2O)
Pin 3 + VS
Pin 1 Laser Trimmed On–Chip
Figure 1. Pressure Sensor MPXM2000 Series
POWER OPTO is a trademark of Motorola Inc.
Motorola Sensor Device Data For More Information On This Product,
© Motorola, Inc. 2002
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