Sensors

4

Freescale Semiconductor

MPX4250D

ON-CHIP TEMPERATURE COMPENSATION AND CALIBRATION

Figure 2. Cross Sectional Diagram (not to scale)

Figure 3. Recommended Power Supply Decoupling and Output Filtering

(For additional output filtering, please refer to Application Note AN1535)

Figure 4. Output versus Absolute Pressure

Figure 2 illustrates the differential/gauge pressure 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.

The MPX4250D 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 3 shows the recommended decoupling circuit for

interfacing the output of the integrated sensor to the A/D input

of a microprocessor or microcontroller.

Figure 4 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 3. The

output will saturate outside of the specified pressure range.

Stainless Steel

Metal Cover

Epoxy Case

RTV Die Bond

P2

Sealed Vacuum Reference

Lead Frame

Wire Bond

Die

P1

Fluoro Silicone

Die Coat

+5 V

1.0 µF

0.01 µF

470 pF

GND

IPS

Output

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

Pressure in kPa

TYP

MIN

MAX

Transfer Function:

Temperature = 0 to 85°C