Datasheet

DocID17530 Rev 2 19/54
LIS3DH Terminology and functionality
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The LIS3DH features a Data-Ready signal (DRDY) which indicates when a new set of
measured acceleration data is available, thus simplifying data synchronization in the digital
system that uses the device.
The LIS3DH may also be configured to generate an inertial wake-up and free-fall interrupt
signal accordingly to a programmed acceleration event along the enabled axes. Both free-
fall and wake-up can be available simultaneously on two different pins.
3.5 Factory calibration
The IC interface is factory calibrated for sensitivity (So) and Zero-g level (TyOff).
The trim values are stored inside the device in non-volatile memory. Any time the device is
turned on, these values are downloaded into the registers to be used during active
operation. This allows using the device without further calibration.
3.6 FIFO
The LIS3DH contains a 10-bit, 32-level FIFO. Buffered output allows 4 operation modes:
FIFO, Stream, Stream-to-FIFO and FIFO bypass. When FIFO bypass mode is activated,
FIFO is not operating and remains empty. In FIFO mode, measurement data from
acceleration detection on the x, y, and z axes are stored in the FIFO buffer.
3.7 Auxiliary ADC and temperature sensor
The LIS3DH contains an auxiliary ADC with 3 separate dedicated inputs: pins ADC1, ADC2,
ADC3.
The user can retrieve the converted data from registers OUT_ADC1_L (08h),
OUT_ADC1_H (09h), OUT_ADC2_L (0Ah), OUT_ADC2_H (0Bh) and OUT_ADC3_L (0Ch),
OUT_ADC3_H (0Dh).
In order to use the auxiliary ADC, the user must set the BDU bit (bit 7) to 1 in CTRL_REG4
(23h) and the ADC_EN bit (bit 7) to 1 in TEMP_CFG_REG (1Fh). The ADC sampling
frequency is the same as that of the ODR in CTRL_REG1 (20h).
The input range is 1200 mv ±400 mV and the data output is expressed in 2's complement
left-aligned.
The ADC resolution is 10 bits if the LPen (bit 3) in CTRL_REG1 (20h) is cleared (high-
resolution / normal mode), otherwise, in low-power mode, the ADC resolution is 8-bit.
Channel 3 of the ADC can be connected to the temperature sensor by setting the
TEMP_EN bit (bit 6) to 1 in TEMP_CFG_REG (1Fh). Refer to Table 5: Temperature sensor
characteristics for the conversion factor.