Using FIFO modes

AN4450

20/26

DocID025978 Rev 1

Figure 9. Hardware digital filter

The digital filter reduces the pressure noise level to 0.010 hPa rms (1 Pa at 1 sigma) and

allows to reduce the internal ADC HW average, reducing power consumption while keeping

the same pressure noise level.

Filter enabling and suggested configuration

To reduce power consumption while keeping a low noise figure, the recommendation is to

reduce the pressure and temperature averaging, reduce ODR to minimum and enable the

digital filter (FIFO).

For example:



RES_CONF(0x10) = 0x05 (set AVGT=16, AVGP=32, or less)



FIFO_CTRL (0x2E) = 0xC1 (Set FIFO Mean mode with average on 2 samples or more,

up to 0xDF)



CTRL_REG2 (0x21) = 0x40 (FIFO enabled, decimation disabled)



CTRL_REG1 (0x20) = 0x90 (ODR = 1 Hz, power-on device)

In this way, the power consumption at 1 Hz is reduced from the typical 26.4 µA to about 4.5

µA with a pressure noise of 0.01 hPa rms.