MPX10

Sensors

4

Freescale Semiconductor

Pressure

Temperature Compensation

MPX10 series over temperature.

Because this strain gauge is an integral part of the silicon

diaphragm, there are no temperature effects due to

differences in the thermal expansion of the strain gauge and

the diaphragm, as are often encountered in bonded strain

gauge pressure sensors. However, the properties of the

strain gauge itself are temperature dependent, requiring that

the device be temperature compensated if it is to be used

over an extensive temperature range.

Temperature compensation and offset calibration can be

achieved rather simply with additional resistive components,

or by designing your system using the MPX2010D series

sensor.

LINEARITY

Linearity refers to how well a transducer’s output follows

calculating nonlinearity: 1) end point straight line fit 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.

Freescale’s specified pressure sensor linearities are based

on the end point straight line method measured at the

midrange pressure.

Figure 4 illustrates the differential or gauge configuration

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 MPX10 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.Refer to application note AN3728, for more

information regarding media compatibility.

Figure 2. Output vs. Pressure Differential

Figure 3. Linearity Specification Comparison

Figure 4. Unibody Package — Cross-Sectional Diagram

(Not to Scale)

Pressure Differential

80

70

60

50

40

30

20

10

0

0

0.3

2.0

0.6

4.0

0.9

6.0

1.2

8.0

10

1.5

PSI

kPa

Span

Range

(Typ)

Offset

(Typ)

MPX10

P1 > P2

-40°C

+25°C

+125°C

Linearity

Actual

Theoretical

Offset

Max

Pressure (kPa)

70

60

50

40

30

20

10

0

0

Span

Silicone

Die Coat

Die

P1

P2

Wire Bond

Lead Frame

RTV Die

Bond

Epoxy

Case

Stainless Steel

Metal Cover