ALS-PDIC17-57B-TR8 Datasheet, PDF (13/19 Pages) Everlight Electronics Co., Ltd – Surface - Mount I2C Digital Ambient Light Sensor

Surface - Mount
I²C Digital Ambient Light Sensor
ALS-PDIC17-57B/TR8
(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
0x29 followed by a command byte of 0x30.
(5). To read the ADC conversion result, issue an Receive Word protocol (see Figure 13-c)
with the device address 0x29 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 this cases, the power consumption of the device can be reduced by issue
a send Byte protocol with the device address 0x29 followed by a data byte of
1xxx_xxxx.(Binary code)
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 nx16.66ms (n = 1, 2...n_i) is zero.
Similarly, setting the ALS-PDIC17-57B integration time to an integer multiple of periodic noise
signal greatly improves the light sensor output signal in the presence of noise. The maximum
detection range is inversely proportional to the integration time; that means the longer
integration time the lower detection range. (See Table 3)
Table 3 Detection Range Guide
Integration time
( mS )
50
100
200
300
400
Detection range
( Lux )
88,400
44,200
22,200
14,500
11,100
Resolution
( Lux / count )
2.7
1.35
0.68
0.45
0.34
Everlight Electronics Co., Ltd.
Document No: DLS-00000xx Rev0.1
13
http://www.everlight.com
Jun. 22, 2011