ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING
Figure 3 illustrates both the Differential/Gauge and the
Absolute Sensing Chip in the basic chip carrier (Case 867).
A fluorosilicone gel isolates the die surface and wire bonds
from the environment, while allowing the pressure signal to
be transmitted to the sensor diaphragm. (For use of the
MPX5700D in a high-pressure cyclic application, consult the
factory.)
The MPX5700 series pressure sensor operating
characteristics, and internal reliability and qualification tests
are based on use of dry air as the pressure media. Media,
other than dry air, may have adverse effects on sensor
performance and long-term reliability. Contact the factory for
information regarding media compatibility in your application.
Figure 2 shows the sensor output signal relative to
pressure input. Typical, minimum, and maximum output
curves are shown for operation over a temperature range of
0° to 85°C using the decoupling circuit shown in Figure 4. The
output will saturate outside of the specified pressure range.
Figure 4 shows the recommended decoupling circuit for
interfacing the output of the integrated sensor to the A/D input
of a microprocessor or microcontroller. Proper decoupling of
the power supply is recommended.
5.0
Transfer Function:
4.5
V
V
out = VS*(0.0012858*P+0.04) ± Error
S = 5.0 Vdc
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Temperature = 0 to 85°C
Typical
Maximum
Minimum
200
400
500
600
700
800
0
100
300
Differential Pressure (kPa)
Figure 2. Output versus Pressure Differential
Fluoro Silicone
Die Coat
Fluoro Silicone
Stainless Steel
Metal Cover
Stainless Steel
Metal Cover
Die Coat
Die
Die
P1
P2
P1
P2
Wire Bond
Wire Bond
Lead Frame
Lead Frame
RTV Die
Bond
RTV Die
Bond
Epoxy Case
Epoxy Case
DIFFERENTIAL/GAUGE ELEMENT
ABSOLUTE ELEMENT
Figure 3. Cross-Sectional Diagrams (not to scale)
+5 V
Output
Vout
Vs
IPS
1.0 µF
GND
470 pF
0.01 µF
Figure 4. Recommended Power Supply Decoupling and Output Filtering
(For additional output filtering, please refer to Application Note AN1646)
MPX5700
Sensors
Freescale Semiconductor
3
FREESCALE [ Freescale ]
