MS5561C Datasheet, PDF (11/21 Pages) TE Connectivity Ltd – High accuracy temperature measurement

MS5561C
Micro Altimeter
Start
Read calibration data (factory calibrated) from
PROM of MS5561C
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
(15 Bit)
(12 Bit)
(10 Bit)
(10 Bit)
(11 Bit)
(6 Bit)
SENST1
OFFT1
TCS
TCO
Tref
TEMPSENS
Example:
Word1 = 46940
Word2 = 40217
Word3 = 25172
Word4 = 47212
C1 = 23470
C2 = 1324
C3 = 737
C4 = 393
C5 = 628
C6 = 25
Read digital pressure value from MS5561C
D1 (16 Bit)
Read digital temperature value from MS5561C
D2 (16 Bit)
Calculate calibration temperature
UT1 = 8*C5+20224
Calculate actual temperature
Difference between actual temperature and reference
temperature:
dT = D2 - UT1
Actual temperature:
TEMP = 200 + dT*(C6+50)/2¹⁰ (0.1°C resolution)
dT(D2) = D2 - Tref
TEMP(D2) = 20°+dT(D2)*TEMPSENS
Calculate temperature compensated pressure
Offset at actual temperature:
OFF = C2*4 + ((C4-512)*dT)/2¹²
Sensitivity at actual temperature:
SENS = C1 + (C3*dT)/2¹⁰ + 24576
X = (SENS * (D1-7168))/2¹⁴ - OFF
Temperature compensated pressure:
P = X*10/2⁵ + 250*10 (0.1 mbar resolution)
OFF(D2) = OFFT1+TCO*dT(D2)
SENS(D2) = SENST1+TCS*dT(D2)
P(D1,D2) = D1*SENS(D2)-OFF(D2)
D1 = 16460
D2 = 27856
UT1 = 25248
dT = 2608
TEMP = 391
= 39.1 °C
OFF = 5220
SENS = 49923
X = 23093
P = 9716
= 971.6 mbar
Display pressure and temperature value
Fig. 3: Flow chart for pressure and temperature reading and software compensation
SENSOR SOLUTIONS ///MS5561C
09/2015
Page 11