ALS-PDIC17-79NB-TR8 Datasheet, PDF (13/21 Pages) Everlight Electronics Co., Ltd – I2 Digital Ambient Light Sensor

Surface - Mount
I²C Digital Ambient Light Sensor
ALS-PDIC17-79NB/TR8
(4). If a conversion has not been completed since being activated, the valid bit ( D[15] ) will be 0 to
indicate that the data is not valid. If there is a valid conversion result available, the valid bit ( D[15] )
will be set logic high, and the remaining 15 bits will represent valid data from the ADC register.
(5). Data may be read repeatedly from the ADC register, and although it will remain valid, the ADC
register will not be updated until a new conversion completes.
Case 2: Using external integration timing
(1). After being powered on, the device will initially be in the shut-down mode (default setting).
(2). To operate the device, issue an Send Byte protocol (see Figure 11-a) with the device address 0x39
followed by a command byte of 0x04 to activate the ambient light sensor and put the device into "one
time integration mode".
(3). I²C master sends a "start integration command" to the salve device by issuing Send Byte protocol
with the device address 0x39 followed by a command byte of 0x08.
(4). After a period of user defined integration time, I²C master sends a "stop integration command" to the
salve device by issuing Send Byte protocol with the device address 0x39 followed by a command
byte of 0x30.
(5). To read the ADC conversion result, issue an Receive Word protocol (see Figure 11-c) with the device
address 0x39 followed by two-byte reading procedures.
(6). If the stop integration command is not received by the device, the valid bit ( D[15] ) will be 0 to
indicate that the data is not valid. If there is a valid conversion result available, the valid bit ( D[15] )
will be set logic high, and the remaining 15 bits will represent valid data from the ADC register.
(7). Data may be read repeatedly from the ADC register, and although it will remain valid, the ADC
register will not be updated until a new complete integration cycle has been carried out.
In both cases, the power consumption of the device can be reduced by issue an Send Byte protocol
with the device address 0x39 followed by a data byte of 0x8C.
Noise Rejection and Integration Time
In general, integrating type ADC’s have an excellent noise rejection characteristics for periodic noise
sources whose frequency is an integer multiple of the integration time. For instance, a 60Hz AC unwanted
signal’s sum from 0ms to n*16.66ms (n = 1,2...ni) is zero.
Everlight Electronics Co., Ltd.
Document No: DLS-xxxxxxx Rev1
13
http://www.everlight.com
Oct. 12, 2010