98ASB42280B Просмотр технического описания (PDF) - NXP Semiconductors.

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98ASB42280B

MPX53, 0 to 50 kPa, Differential and Gauge, Uncompensated, Silicon Pressure Sensors

NXP Semiconductors. 

2.3 Voltage output versus applied differential pressure

The differential voltage output of the sensor is directly proportional to the differential pressure (P1) relative to the vacuum side

(P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side

(P1).

2.4 Temperature compensation

Figure 3 shows the typical output characteristics of the MPX53 series over temperature.

The piezoresistive pressure sensor element is a semiconductor device which gives an electrical output signal proportional to the

pressure applied to the device. This device uses a unique transverse voltage diffused semiconductor strain gauge which is

sensitive to stresses produced in a thin silicon diaphragm by the applied pressure.

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 MPX2053 series sensors.

Several approaches to external temperature compensation over –40 to +125 °C and 0 to +80 °C are presented in Freescale

Application Note, AN840.

2.5 Linearity

Linearity refers to how well a transducer's output follows the equation: VOUT = VOFF + (sensitivity x P) over the operating pressure

range (see Figure 3). There are two basic methods for 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 unibody chip carrier (Case 98ASB42280B). 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 MPX53 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.

Refer to application note AN3728, for more information regarding media compatibility.

100

90

80

70

60

50

40

30

20

10

0

PSI

0

kPa 0

MPX53

VS = 3 Vdc

P1 > P2

12

10

–40°C

+ 25°C

+ 125ºC

3 4 5 67

20

30

40

50

Pressure Differential

Span

Range

(Typ)

Offset

(Typ)

8

Figure 3. Output vs. pressure differential

Sensors

Freescale Semiconductor, Inc.

MPX53

5

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