MS5540C Datasheet, PDF (11/18 Pages) Intersema Sensoric SA – MINIATURE BAROMETER MODULE

C1 (15 Bit)
C5/I
1 Bit
Word1
DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB10
Word2
C5/II (10 Bit)
C6 (6 Bit)
DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB5 DB4 DB3 DB2 DB1 DB0
Word3
C4 (10 Bit)
C2/I (6 Bit)
DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 DB11 DB10 DB9 DB8 DB7 DB6
Word4
C3 (10 Bit)
C2/II (6-Bit)
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 best 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:
TEMP < 200
yes
Low Temperatures
T2 = 11*(C6+24)*(200 - TEMP)*(200 – TEMP) / 2²⁰
P2 = 3 *T2 * (P - 3500)/2¹⁴
200 ≤ TEMP ≤ 450
TEMP > 450
yes
No correction
T2 = 0
P2 = 0
yes
High Temperatures
T2 = 3*(C6+24)*(450 - TEMP)*(450 – TEMP) / 2²⁰
P2 = T2 * (P - 10000)/2¹³
Calculate pressure and temperature
TEMP = TEMP – T2
P = P – P2
Fig. 5: Flow chart for calculating the temperature and pressure to the optimum accuracy.
DA5540C_003
June 16th, 2008
11
0005540C1193 ECN 1118