TCS3771 Datasheet, PDF (11/33 Pages) ams AG – COLOR LIGHT-TO-DIGITAL CONVERTER with PROXIMITY SENSING

TCS3771
COLOR LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS110A − MARCH 2011
RGBC Operation
The RGBC engine contains RGBC gain control (AGAIN) and four integrating analog-to-digital converters (ADC)
for the RGBC photodiodes. The RGBC integration time (ATIME) impacts both the resolution and the sensitivity
of the RGBC reading. Integration of all four channels occurs simultaneously and upon completion of the
conversion cycle, the results are transferred to the color data registers. This data is also referred to as channel
count. The transfers are double-buffered to ensure that invalid data is not read during the transfer. After the
transfer, the device automatically moves to the next state in accordance with the configured state machine.
ATIME(r 1)
2.4 ms to 700 ms
AGAIN(r 0x0F, b1:0)
1y, 4y, 16y, 60y Gain
lid _{RGBC Control}
a _Clear
v _Red
ill ^Green
Blue
Clear ADC
Red ADC
Green ADC
Blue ADC
Clear Data
Red Data
Green Data
Blue Data
CDATAH(r 0x15), CDATA(r 0x14)
RDATAH(r 0x17), RDATA(r 0x16)
GDATAH(r 0x19), GDATA(r 0x18)
BDATAH(r 0x1B), BDATA(r 0x1A)
G _{st Figure 8. RGBC Operation}
A ^t _{The registers for programming the integration and wait times are a 2’s compliment values. The actual time can}
be calculated as follows:
s ^{n ATIME = 256 − Integration Time / 2.4 ms}
e _{Inversely, the time can be calculated from the register value as follows:}
m ^{t Integration Time = 2.4 ms × (256 − ATIME)}
For example, if a 100-ms integration time is needed, the device needs to be programmed to:
a ⁿ 256 − (100 / 2.4) = 256 − 42 = 214 = 0xD6
o _{Conversely, the programmed value of 0xC0 would correspond to:}
Technical ^{c (256 − 0xC0) × 2.4 = 64 × 2.4 = 154 ms.}
Copyright E 2011, TAOS Inc.
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