tcs3771 ETC-unknow, tcs3771 Datasheet - Page 2

• Manufacturer Part Number: tcs3771
• Description: Color Light-to-digital Converter With Proximity Sensing
• Manufacturer: ETC-unknow

TCS3771
COLOR LIGHT-TO-DIGITAL CONVERTER
with PROXIMITY SENSING
TAOS110A − MARCH 2011
Functional Block Diagram
Detailed Description
2
Copyright E 2011, TAOS Inc.
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.
The TCS3771 light-to-digital device contains a 4 × 4 photodiode array, integrating amplifiers, ADCs,
accumulators, clocks, buffers, comparators, a state machine, and an I
is composed of red-filtered, green-filtered, blue-filtered, and clear photodiodes — four of each type. Four
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
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 I
connection to a microcontroller or embedded controller.
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
interrupt feature simplifies and improves system efficiency by eliminating the need to poll a sensor for a light
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
the user to determine how many consecutive exceeded thresholds are necessary to trigger an interrupt.
Interrupt thresholds and persistence settings are configured independently for both RGBC and proximity.
V
DD
GND
LDR
Clear
Red
Integration
Green
Prox
Blue
r
IR LED Constant
Green ADC
Clear ADC
Blue ADC
Prox
ADC
Red ADC
Current Sink
Prox Control
Wait Control
www.taosinc.com
RGBC Control
Prox
Data
Green Data
Clear Data
Blue Data
Red Data
Upper Limit
Lower Limit
Upper Limit
Lower Limit
2
C interface. The 4 × 4 photodiode array
r
Interrupt
The LUMENOLOGY r Company
2
C serial bus for easy
SCL
SDA
INT