MPX7050 SERIES

3

Motorola Sensor Device Data

LINEARITY

Linearity refers to how well a transducer’s output follows

the equation: Vout = Voff + sensitivity x P over the operating

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. Motorola’s

specified pressure sensor linearities are based on the end

point straight line method measured at the midrange

pressure.

Figure 2. Linearity Specification Comparison

LEAST

SQUARE

DEVIATION

PRESSURE (% FULLSCALE)

0

50

100

END POINT

STRAIGHT LINE FIT

EXAGGERATED

PERFORMANCE

CURVE

LEAST SQUARES FIT

STRAIGHT LINE

DEVIATION

OFFSET

ON–CHIP TEMPERATURE COMPENSATION and CALIBRATION

Figure 3 shows the output characteristics of the MPX7050

series at 25

°C. The output is directly proportional to the dif-

ferential 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.

Figure 3. Output versus Pressure Differential

Figure 4. Cross–Sectional Diagram

(not to scale)

SILICONE

DIE COAT

WIRE BOND

LEAD FRAME

DIE

STAINLESS STEEL

METAL COVER

EPOXY

CASE

RTV DIE

BOND

P1

P2

DIFFERENTIAL/GAUGE ELEMENT

40

35

30

25

20

15

10

5

0

–5

0

12.5

1.83

25

3.63

37.5

5.44

50

7.3

SPAN

RANGE

(TYP)

OFFSET

(TYP)

kPa

PSI

VS = 10 Vdc

TA = 25°C

P1 > P2

MAX

TYP

MIN

Figure 4 illustrates the differential or gauge configuration

in the basic chip carrier (Case 344–15). A silicone gel iso-

lates the die surface and wire bonds from the environment,

while allowing the pressure signal to be transmitted to the sil-

icon diaphragm.

The MPX7050 series pressure sensor operating charac-

teristics 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 perfor-

mance and long term reliability. Contact the factory for in-

formation regarding media compatibility in your application.