SI1133 Datasheet, PDF (26/43 Pages) Silicon Laboratories – UV Index/Ambient Light Sensor IC with IC Interface

Si1133 Data Sheet
Measurement: Principle of Operation
6.4 Interrupt Operation
The INT output pin is asserted by the sensor when an enabled channel in the CHAN_LIST (which has the corresponding bit in the
RESET register) has finished. In Burst Mode, the interrupt is delayed until the number of readings is reached or the buffer is full.
When the host reads the IRQ_STATUS register to learn which source generated the interrupt, the IRQ_STATUS register is cleared
automatically.
The most efficient method of extracting measurements from the Si1133 is an I²C Burst Read beginning at the IRQ_STATUS register.
6.5 Timing of Channel Measurements
The timing of measurements has two aspects:
1. The length of time to take a measurement.
2. How frequently the measurement is taken.
The amount of time to take the measurement is controlled by factors like HW_GAIN (which is really the integration time), SW_GAIN,
and the decimation rate setting.
Note: Each measurement is composed of two measurement times.
In an ALS measurement, two measurements are always taken and added together.
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