TCS3771 Datasheet, PDF (3/33 Pages) ams AG – COLOR LIGHT-TO-DIGITAL CONVERTER with PROXIMITY SENSING

TCS3771
COLOR LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS110A − MARCH 2011
The proximity function is targeted specifically towards battery-powered mobile devices, LCD monitor, laptop,
and flat-panel television applications. In cell phones, the proximity detection can detect when the user positions
the phone close to their ear. The device is fast enough to provide proximity information at a high repetition rate
needed when answering a phone call. It can also detect both close and far distances so the application can
implement more complex algorithms to provide a more robust interface. In laptop or monitor applications, the
product is sensitive enough to determine whether a user is in front of the laptop using the keyboard or away from
the desk. This provides both improved green power saving capability and the added security to lock the
computer when the user is not present.
Functional Block Diagram
lid _LDR
IR LED Constant
Current Sink
Interrupt
INT
va GND
Prox
Integration
Prox Control
Prox
ADC
Prox
Data
Upper Limit
ill Lower Limit
SCL
Wait Control
V_DD
t _{RGBC Control}
Upper Limit
G _{s Clear ADC Clear Data}
Clear
SDA
A ^{t Red ADC Red Data}
Lower Limit
Red
s ^{n Green}
Green ADC Green Data
Blue ADC Blue Data
e ^Blue
am _{ont Detailed Description}
c _{The TCS3771 light-to-digital device contains a 4 × 4 photodiode array, integrating amplifiers, ADCs,}
l ^{accumulators, clocks, buffers, comparators, a state machine, and an I2C interface. The 4 × 4 photodiode array}
is composed of red-filtered, green-filtered, blue-filtered, and clear photodiodes — four of each type. Four
a ^{integrating ADCs simultaneously convert the amplified photodiode currents to a digital value providing up to 16}
bits of resolution. Upon completion of the conversion cycle, the conversion result is transferred to the data
ic ^{registers. The transfers are double-buffered to ensure that the integrity of the data is maintained.}
Communication to the device is accomplished through a fast (up to 400 kHz), two-wire I²C serial bus for easy
connection to a microcontroller or embedded controller.
n _{The TCS3771 provides a separate pin for level-style interrupts. When interrupts are enabled and a pre-set value}
is exceeded, the interrupt pin is asserted and remains asserted until cleared by the controlling firmware. The
h _{interrupt feature simplifies and improves system efficiency by eliminating the need to poll a sensor for a light}
c ^{intensity or proximity value. An interrupt is generated when the value of an RGBC or proximity conversion}
exceeds either an upper or lower threshold. In addition, a programmable interrupt persistence feature allows
e the user to determine how many consecutive exceeded thresholds are necessary to trigger an interrupt.
T^{Interrupt thresholds and persistence settings are configured independently for both RGBC and proximity.}
Copyright E 2011, TAOS Inc.
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www.taosinc.com
The LUMENOLOGY r Company
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