
3–386
Motorola Sensor Device Data
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MPX2000 Series:
The MPX2000 Series sensors (MPX2010, MPX2050,
MPX2100, and MPX2200) add span compensation and trim
resistors to the Uncompensated model. These resistors are
shown in Figure 2 as RS9, RS11, and RS10. The temperature
coefficient of resistance (TCR) for the bridge resistors works
against fixed resistors RS9 and RS11 to produce a bias to the
bridge that increases with temperature. This increasing bias
compensates for the temperature coefficient of span, which is
negative.
Resistor RS12 is also added to the Uncompensated model.
It represents additional impedance that is associated with the
MPX2000 series sensors’ offset trim network. Offset perfor-
mance is modeled behaviorally. Inputs for offset (VOFFSET)
and temperature coefficient of offset (TCOS) are translated
into bridge resistance values that produce the specified per-
formance. This behavioral approach was chosen in order to
make it easy to plug in different values for VOFFSET and
TCOS.
Figure 2. MPX2000 Series PSPICE Compound Coefficient Model
6
0
2
4
5
1
3
7
8
**
**
**
**
*
*
NOTES:
*TEMPERATURE SENSITIVE
**TEMPERATURE & PRESSURE SENSITIVE
RS11
RS4
RS1
RS2
RS3
RS9
RS8
RS7
RS12
RS5
RS6
RS10
MPX5000 Series:
The MPX5000 Series sensors (MPX5010, MPX5050,
MPX5100, MPX5700, and MPX5999) add an instrumentation
amplifier to the MPX2000 series model. This amplifier is
shown in Figure 3. It consists of operational amplifiers ES1,
ES2, ES3, and ES4. Amplifiers ES1, ES2 and ES3 are mod-
eled as voltage controlled voltage sources with gains of
100,000. Offset voltage, input bias current effects, etc. are tak-
en into account with the values that are used to determine off-
set voltage and temperature coefficient of the sensor bridge.
Amplifier ES4 models saturation voltage. Its output follows the
output of ES3 with saturation limits at 75 millivolts and 4.9 volts.
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Freescale Semiconductor, Inc.
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