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AS7331

Functional Description

Datasheet

• PUBLIC

DS001047

• v4-00 • 2023-Mar-24

│ 15

Functional Description

The AS7331 includes three internal photodiodes with different spectral sensitivities and three ADCs,

each one for each spectral photodetector. The irradiance responsivity Re and the time of conversion

TCONV are user-defined and determined by the registers CREG1:GAIN and CREG1:TIME. Both, Gain

and conversion time can be adapted to match the measurement conditions. At the end of each

conversion, the digital equivalents of the filtered input light signal regarding the area of the sensor are

stored in the output registers (MRES1 … MRES3). With the divider, the 16-bit of interest can be

selected out of the 24-bit ADC output. Additionally, a temperature sensor works in parallel to the three

optical channels, delivering the on-chip temperature at the end of conversion. The READY pin remains

at a low logic level during the conversion. The rising edge and the following high logic level of READY

signal, the end of the conversion. Internal information related to the conversion is available in a status

Figure 10:

Photodiode Array

7.1

Operational States

The AS7331 operates in two different states

“Configuration” and “Measurement”. The three least

significant bits of the Operational State Register (OSR) as Device Operational State (DOS) define the

current state. After applying the power supply voltage, including power-on reset, or after software

reset, the AS7331 stays in the Power-Down state. Then it is ready to be programmed via the I²C

interface. When Power-Down is switched off (OSR: PD set to

‚0‘), the AS7331 starts in the

Configuration state (CONFIG) or the Measurement state (MMODE) according to its DOS

programming.

AS7331 数据表(PDF) 16 Page - OSRAM GmbH