DA5541B_005.doc

10

00005541766 ECN865

Example:

Word1, Word2, Word3 and Word4 (4x16 Bit)

D1 = 17788

D2 = 26603

Start

Convert calibration data into coefficients:

(see bit pattern of Word1-Word4)

Read calibration data (factory calibrated) from

PROM of MS5541

Read digital pressure value from MS5541

D1 (16 Bit)

Read digital temperature value from MS5541

Display pressure and temperature value

Basic equations:

Calculate calibration temperature

UT1=8*C5+10000

Calculate temperature compensated pressure

Difference between actual temperature and reference

temperature:

dT = D2 - UT1

Actual temperature:

resolution)

Calculate actual temperature

D2 (16 Bit)

SENST1

OFFT1

TCS

TCO

TEMPSENS

C1: Pressure sensitivity

(13 Bit)

C2: Pressure offset

(13 Bit)

C3: Temperature coefficient of pressure sensitivity (10 Bit)

C4: Temperature coefficient of pressure offset

(9 Bit)

C5: Reference Temperature

(12 Bit)

C6: Temperature coefficient of the temperature

(7 Bit)

Word1 = 18556

Word2 = 49183

Word3 = 22354

Word4 = 28083

C1 = 2319

C2 = 4864

C3 =

349

C4 =

219

C5 = 2002

C6 =

51

TEMP(D2)=20°+dT(D2)*TEMPSENS

Offset at actual temperature:

Sensitivity at actual temperature:

Temperature compensated pressure in mbar:

OFF(D2)=OFFT1+TCO*dT(D2)

SENS(D2)=SENST1+TCS*dT(D2)

P(D1,D2)=D1*SENS(D2)-OFF(D2)

dT

= 587

TEMP = 243

= 24.3 °C

OFF = 14859

SENS = 4198

P

= 4001

= 4001 mbar

UT1 = 26016

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.