MS5540C

Miniature Barometer Module

09/2015

Page 12

NOTES

1)

Readings of D2 can be done less frequently, but the display will be less stable in this case.

2) For a stable display of 1 mbar resolution, it is recommended to display the average of 8 subsequent

pressure values.

C1 (15 Bit)

C5/I

1 Bit

Word1

DB14

DB13

DB12

DB11

DB10

DB9

DB8

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

DB10

C5/II (10 Bit)

C6 (6 Bit)

Word2

DB9

DB8

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

DB5

DB4

DB3

DB2

DB1

DB0

C4 (10 Bit)

C2/I (6 Bit)

Word3

DB9

DB8

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

DB11

DB10

DB9

DB8

DB7

DB6

C3 (10 Bit)

C2/II (6-Bit)

Word4

DB9

DB8

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

DB5

DB4

DB3

DB2

DB1

DB0

Fig. 4: Arrangement (Bit-pattern) of calibration data in Word1 to Word4

SECOND-ORDER TEMPERATURE COMPENSATION

In order to obtain full temperature accuracy over the whole temperature range, it is recommended to compensate

for the non-linearity of the output of the temperature sensor. This can be achieved by correcting the calculated

temperature and pressure by a second order correction factor. The second-order factors are calculated as follows:

Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.

No correction

T2 = 0

P2 = 0

High Temperatures

P2 = T2 * (P - 10000)/2

13

TEMP < 200

yes

Calculate pressure and temperature

TEMP = TEMP – T2

P = P – P2

Low Temperatures

P2 = 3 *T2 * (P - 3500)/2

14

TEMP > 450

yes

200



TEMP



450

yes