ILPS22QSTR datasheet(13/57 Pages) STMICROELECTRONICS

No de pièce	ILPS22QSTR

Description	Dual full-scale, 1260 hPa and 4060 hPa, absolute digital output barometer with embedded Qvar electrostatic sensor

PDF	57 Pages

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Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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4.4

Interpreting pressure readings

The pressure data are stored in three registers: PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and

PRESS_OUT_XL (28h). The value is expressed as a 24-bit signed number (in two's complement).

To obtain the pressure in hPa, take the complete 24-bit word and then divide by the sensitivity 4096

LSB/hPa when the FS_MODE bit is 0 (in mode 1, full scale is up to 1260 hPa) or divide by the

sensitivity 2096 LSB/hPa when the FS_MODE bit is 1 (in mode 2, full scale is up to 4060 hPa).

This same interpretation is applied to pressure readings when FIFO is enabled and the pressure data

are stored in three registers:FIFO_DATA_OUT_PRESS_XL (78h), FIFO_DATA_OUT_PRESS_L (79h), and

FIFO_DATA_OUT_PRESS_H (7Ah).

Figure 6. Pressure readings

(1)

PressureValue=PRESS_OUT_H2Aℎ &PRESS_OUT_L29ℎ &PRESS_OUT_XL 28ℎ =3FF58Dℎ=4191629LSB signeddecimal

(2)

When FS_MODE bit = 0 (CTRL_REG2 (11h)), for full scale up to 1260 hPa:

Pressure ℎPA =Pressurevalue LSB

Sensitivity = 4191629LSB

4096LSB/ℎPA=1023.3ℎPA

When FS_MODE bit = 1 (CTRL_REG2 (11h)), for full scale up to 4060 hPa:

Pressure ℎPA =Pressurevalue LSB

Sensitivity = 4191629LSB

2048LSB/ℎPA=2046.7ℎPA

ILPS22QS

Interpreting pressure readings

DS13431 - Rev 3

page 13/57

ILPS22QSTR Fiches technique(PDF) 13 Page - STMicroelectronics