MS5541C Datasheet, PDF (11/19 Pages) Intersema Sensoric SA – MINIATURE 14 bar MODULE

Start
Read calibration data (factory calibrated) from
PROM of MS5541
Word1, Word2, Word3 and Word4 (4x16 Bit)
Basic equations:
Convert calibration data into coefficients:
(see bit pattern of Word1-Word4)
C1: Pressure sensitivity
C2: Pressure offset
C3: Temperature coefficient of pressure sensitivity
C4: Temperature coefficient of pressure offset
C5: Reference Temperature
C6: Temperature coefficient of the temperature
(13 Bit)
(13 Bit)
(10 Bit)
(9 Bit)
(12 Bit)
(7 Bit)
SENST1
OFFT1
TCS
TCO
Tref
TEMPSENS
Example:
Word1 = 18556
Word2 = 49183
Word3 = 22354
Word4 = 28083
C1 =
C2 =
C3 =
C4 =
C5 =
C6 =
2319
4864
349
219
2002
51
Read digital pressure value from MS5541
D1 (16 Bit)
Read digital temperature value from MS5541
D2 (16 Bit)
Calculate calibration temperature
UT1=8*C5+10000
Calculate actual temperature
Difference between actual temperature and reference
temperature:
dT = D2 - UT1
Actual temperature:
TEMP = 200 + dT*(C6+100)/2¹¹ (0.1°C)
dT(D2) = D2 - T_ref
TEMP(D2)=20°+dT(D2)*TEMPSENS
Calculate temperature compensated pressure
Offset at actual temperature:
OFF = C2 + ((C4-250)*dT)/2¹² + 10000
Sensitivity at actual temperature:
SENS = C1/2 + ((C3+200)*dT)/2¹³ + 3000
OFF(D2)=OFFT1+TCO*dT(D2)
SENS(D2)=SENST1+TCS*dT(D2)
Temperature compensated pressure in mbar:
P = (SENS * (D1-OFF))/2¹² + 1000
P(D1,D2)=D1*SENS(D2)-OFF(D2)
D1 = 17788
D2 = 26603
UT1 = 26016
dT = 587
TEMP = 243
= 24.3 °C
OFF = 14859
SENS = 4198
P = 4001
= 4001 mbar
Display pressure and temperature value
Fig. 3: Flow chart for pressure/temperature reading and software compensation.
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 4 to 8 subsequent
pressure values.
DA5541C_004.doc
June 16th, 2008
11
0005541C1194 ECN1118