LSM303AGR datasheet(21/68 Pages) STMICROELECTRONICS

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LSM303AGR

Functionality

4.1

Magnetometer

4.1.1

Magnetometer power modes

The LSM303AGR magnetometer provides two different power modes: high-resolution and

low-power modes.

The tables below summarize the selection of the low-pass filter and current consumption of

the operating modes.

When the low-pass filter is enabled, the bandwidth is reduced while noise performance is

improved without any increase in power consumption.

The following table summarizes the turn-on time of the magnetometer in the two different

power modes with the offset cancellation function enabled or disabled (see Section 4.1.2:

Magnetometer offset cancellation).

Table 10. Digital low-pass filter

CFG_REG_B_M

[LPF]

(CFG_REG_A_M [LP = 0])

high-resolution mode

(CFG_REG_A_M [LP = 1])

low-power mode

BW [Hz]

Noise RMS [mg]

BW [Hz]

Noise RMS [mg]

0 (disable)

ODR/2

8.5

1 (enable)

ODR/4

Table 11. Current consumption of operating modes

ODR

(Hz)

Current consumption (μA)

(CFG_REG_A_M [LP] = 0) - high-resolution

Current consumption (μA)

(CFG_REG_A_M [LP] = 1) - low-power

100

200

500

125

100

1000

250

Table 12. Operating mode and turn-on time

Operating mode

Turn-on time

CFG_REG_A_M[LP]

CFG_REG_A_M[OFF_CANC = 0]

CFG_REG_A_M[OFF_CANC = 1]

0 (high-resolution)

9.4 ms

9.4 ms + 1/ODR

1 (low-power)

6.4 ms

6.4 ms + 1/ODR

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