Sensors

Freescale Semiconductor

3

MPX5700

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.

Figure 2. Output versus Pressure Differential

Figure 3. Cross-Sectional Diagrams (not to scale)

Figure 4. Recommended Power Supply Decoupling and Output Filtering

(For additional output filtering, please refer to Application Note AN1646)

Differential Pressure (kPa)

Typical

Minimum

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0

100

200

300

400

600

500

Maximum

700

800

Transfer Function:

Temperature = 0 to 85°C

Fluoro Silicone

Die Coat

Wire Bond

Die

P1

Stainless Steel

Metal Cover

Lead Frame

RTV Die

Bond

Epoxy Case

P2

Fluoro Silicone

Die Coat

Wire Bond

Die

P1

Stainless Steel

Metal Cover

Lead Frame

RTV Die

Bond

Epoxy Case

P2

ABSOLUTE ELEMENT

DIFFERENTIAL/GAUGE ELEMENT

+5 V

1.0 µF

0.01 µF

470 pF

GND

IPS

Output