M
P
X
2
0
5
0
SE R I ES
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.
L EA S T S Q UA RE S FI T
E X AG G E RATE D
P E RFO RMA NC E
CURV E
STR AI G HT L IN E
D EVI ATIO N
L EA S T
S Q UA RE
DE V I ATI O N
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 pres-
sure.
E ND P O IN T
S TRA I G HT L I NE FI T
O FFS E T
5 0
P RE SS UR E (% FUL L SC AL E )
1 0 0
0
Figure 2. Linearity Specification Comparison
ON–CHIP TEMPERATURE COMPENSATION and CALIBRATION
Figure 3 shows the minimum, maximum and typical output
characteristics of the MPX2050 series at 25°C. The output is
directly proportional to the differential pressure and is essen-
tially a straight line.
The effects of temperature on Full–Scale Span and Offset
are very small and are shown under Operating Characteris-
tics.
V
T
=
1
0
V
d
c
S
4 0
=
°
C
2
5
A
3 5
3 0
2 5
2 0
1 5
1 0
MPX 20 5 0
S TA I NL ES S STE EL
TY P
P
1
>
P
2
S PA N
RA NG E
(T YP )
ME TA L C O VER
S I LI CO NE
M
A
X
D
I
E
C
O
A
T
D
I
E
EP O XY
C ASE
P
1
W IR E B O ND
L EA D FRA ME
M
I
N
5
0
O FFS E T
(T YP )
-
ā
RTV D IE
BO N D
0
12 .5
1. 8
25
3. 6
37 .5
5. 4
5
0
kPa
PSI
7
.
2
5
P
2
Figure 3. Output versus Pressure Differential
Figure 4. Cross–Sectional Diagram (not to scale)
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.
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.
The MPX2050 series pressure sensor operating charac-
Motorola Sensor Device Data
3