MPXM2202

Sensors

4

Freescale Semiconductor

LINEARITY

Linearity refers to how well a transducer's output follows

pressure range. There are two basic methods for calculating

nonlinearity: (1) end point straight line fit (see Figure 2) or

(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. The

specified pressure sensor linearities are based on the end

point straight line method measured at the midrange

pressure.

Figure 2. Linearity Specification Comparison

ON-CHIP TEMPERATURE COMPENSATION AND

CALIBRATION

Figure 3 shows the minimum, maximum and typical output

characteristics of the MPXM2202 series at 25

°C. The output

is directly proportional to the differential pressure and is es-

sentially a straight line.

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.

Figure 3. Output versus Pressure Differential

Pressure(% Fullscale)

050

100

End Point Straight Line Fit

Exaggerated

Performance

Curve

Least Squares Fit

Least

Square

Deviation

Straight Line

Deviation

Offset

Least

Square

Deviation

kPa

PSI

40

35

30

25

15

10

5

0

-5

050

7.25

100

14.5

150

21.75

200

29

20

MAX

TYP

MIN

Offset

(TYP)

Span

Range

(TYP)

25

75

125

175