AS7150 datasheet(32/159 Pages) AMSOSRAM

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AS7150

Functional description

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7.6.3

Measurement modes

AS7150 basic measurement mode is the Single Measurement Mode which does not support

any kind of ambient light compensation. If ambient light compensation measurement modes

are desired, please refer to chapter 7.6.4 Ambient light compensation. However, it’s worth

mentioning that all measurement modes for ambient light compensation do rely on the basic

principle and timing of the Single Measurement mode which is described in this chapter and

illustrated in Figure 22.

7.6.3.1

Single measurement mode

The Single Measurement mode is the simplest measurement which can be selected and

assigned to a subsample. A timing diagram to explain the operation mode and working

principle of the Single Measurement is shown in Figure 22. Once a Single measurement is

executed, the first step in the measurement procedure is that the assigned photodiode is

connected via the internal multiplexers to the selected ADC channel. At the same time a DAC

offset current, which is setup in AOC_MOD1_SEQ1_SUBx and AOC_MOD2_SEQ1_SUBx

a short delay, which can be configured as part of the chip configuration, the LEDs with the

configured LED currents in registers SEQ1_LED1_CURR, SEQ1_LED2_CURR and

SEQ1_LED3_CURR are enabled for the measurement and in parallel, the ADC is started.

After a configurable modulator reset time, the SINC down-sampler filter is fed with data. The

measurement time depends now very much on the configuration of the SINC filter, filter order

and internal clock speed of AS7150. These parameters are typically configured with

SEQ1_MODE_A, SEQ1_MODE_B, SEQ1_SEL_ORDER and SEQ1_SINC_DEC register for

both modulators. Once the measurement time has elapsed the sample data is written to the

FIFO memory and ready for readout by a host MCU. Please refer to chapter 7.6.5 Parameters

for more detailed timing diagrams and timing characteristics.

AS7150 Datasheet(PDF) 32 Page - ams-OSRAM AG