MPX2010

Sensors

4

Freescale Semiconductor

Pressure

On-Chip Temperature Compensation and Calibration

series at 25

°C. The output is directly proportional to the

differential pressure and is essentially a straight line.

The effects of temperature on full scale span and offset are

very small and are shown under Operating Characteristics.

This performance over temperature is achieved by having

both the shear stress strain gauge and the thin-film resistor

circuitry on the same silicon diaphragm. Each chip is

dynamically laser trimmed for precise span and offset

calibration and temperature compensation.

Figure 3. illustrates the differential/gauge die in the basic

chip carrier (Case 344). A silicone gel isolates the die surface

and wire bonds from the environment, while allowing the

pressure signal to be transmitted to the silicon diaphragm.

The MPX2010 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.

LINEARITY

Linearity refers to how well a transducer's output follows

pressure range. There are two basic methods for calculating

(2) a least squares best line fit. While a least squares fit gives

the “best case” linearity error (lower numerical value), the

calculations required are burdensome.

Conversely, an end point fit will give the “worst case” error

(often more desirable in error budget calculations) and the

calculations are more straightforward for the user.

Freescale’s specified pressure sensor linearities are based

on the end point straight line method measured at the

midrange pressure.

Figure 2. Output vs. Pressure Differential

Figure 3. Unibody Package: Cross Sectional Diagram

(not to scale)

Figure 4. Linearity Specification Comparison

Offset

(Typical)

kPa

PSI

2.5

0.362

5

0.725

7.5

1.09

10

1.45

Span

Range

(Typical)

P1 > P2

30

25

20

15

10

5

0

–

5

TYP

MIN

Silicone

Die Coat

Die

P1

P2

Wire Bond

Lead Frame

RTV Die

Bond

Epoxy

Case

Stainless Steel

Metal Cover

Least

Square

Deviation

Pressure (% Full Scale)

0

50

100

End Point Straight

Line Fit

Exaggerated

Performance

Curve

Least Squares Fit

Offset

Straight Line

Deviation