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AS7331

Functional Description

Datasheet

• PUBLIC

DS001047

• v4-00 • 2023-Mar-24

│ 24

In case the Device Operational State (DOS) is set to the measurement mode, the start/stop of

measurement is possible by setting the OSR:SS bit and reading measurement data. The power down

can be switched on and off by the bit OSR:PD (Figure 45). Switching on power down via the bit

SR:PD = “1”, changes the AS7331 to the power down state after the end of an ongoing

measurement. Switching off power down (OSR:PD =

‚0‘) results in a change to the Idle state (IDLE for

waiting) or standby state depending on the bit CREG3:SB. This change to another operational state is

delayed by the startup time (TSTARTPD) typically of 1.2 ms. A conversion can start in all the

measurement modes while the power down

state is activated (OSR:PD = “1”). In the measurement

modes CMD and CONT, it is done by setting the bit OSR:SS to

‚1‘. In addition, the falling edge of the

signal at pin SYN for the measurement modes SYNS and SYND initiate the start. In all cases, the start

of the conversion is delayed by the startup time (TSTARTPD). After the conversion in the CMD, SYNS

and SYND modes, the AS7331 changes back into the power down state, whereas the measurement

of the CONT mode is interactive until it is stopped by setting the bit OSR:SS = to

“0” before it changes

back into the power down state.

There are two methods for startup of the AS7331:

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

OSR:PD bit must be set to “0” via the I²C interface communication. The analog part and the

internal clock system start to work along with the defined configuration of the AS7331.

Nevertheless, it is still possible to change the configuration in front of the time b) in Figure 18.

The Device Operational State changes to the Measurement state to start the measurement

(OSR:SS = “1”) without further delay caused by energy-saving options.

Figure 18 shows the principle sequence after power-on reset and separated writing of the bits

OSR:PD, OSR:DOS, and OSR:SS:

OSR programming: 02h, after TSTARTPD continuing within only the configuration state,

OSR programming: 03h, change to the Measurement state

– waiting is shown as IDLE,

OSR programming: 80h, start of the measurement as stated in t

he device’s configuration.

Figure 18:

Principle Sequence After Power-On Reset and Separated Writing of the Bits OSR:PD, OSR:DOS

and OSR:SS

POWDOWN

MEASUREMENT

CONFIGURATION

IDLE

STATE

TSTARTPD

I²C activity

Start

OSR:SS ← ‚1'

OSR:DOS

011b

OSR:PD ← ‚0'

AS7331 数据表(PDF) 25 Page - ams-OSRAM AG

AS7331 数据表(HTML) 25 Page - ams-OSRAM AG

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