TSL2571 LIGHT-TO-DIGITAL CONVERTER TAOS117A FEBRUARY 2011 PACKAGE FN Features DUAL FLAT NO-LEAD Ambient Light Sensing (ALS) (TOP VIEW) Approximates Human Eye Response Programmable Analog Gain V 1 6 SDA DD Programmable Integration Time Programmable Interrupt Function with SCL 2 5 INT Upper and Lower Threshold GND 3 4 NC Resolution Up to 16 Bits Very High Sensitivity Operates Well Behind Darkened Glass Up to 1,000,000:1 Dynamic Range Applications Programmable Wait Timer Display Management Programmable from 2.72 ms Backlight Control to > 8 Seconds Wait State 65 A Typical Current Portable Device Power Optimization 2 I C Interface Compatible Cell Phones, PDA, GPS 2 Up to 400 kHz (I C Fast Mode) Notebooks and Monitors Dedicated Interrupt Pin LCD TVs Small 2 mm 2 mm ODFN Package Sleep Mode 2.5 A Typical Current Description The TSL2571 family of devices provides ambient light sensing (ALS) that approximates human eye response to light intensity under a variety of lighting conditions and through a variety of attenuation materials. While useful for general purpose light sensing, the device is particularly useful for display management with the purpose of extending battery life and providing optimum viewing in diverse lighting conditions. Display panel and keyboard backlighting can account for up to 30 to 40 percent of total platform power. The ALS features are ideal for use in notebook PCs, LCD monitors, flat-panel televisions, and cell phones. Functional Block Diagram Interrupt INT GND Wait Control Upper Limit CH0 V CH0 DD ADC Data SCL Lower Limit ALS Control CH0 CH1 CH1 SDA ADC Data CH1 The LUMENOLOGY Company Copyright 2011, TAOS Inc. Texas Advanced Optoelectronic Solutions Inc. 1001 Klein Road Suite 300 Plano, TX 75074 (972) 673-0759 www.taosinc.com 1 2 I C InterfaceTSL2571 LIGHT-TO-DIGITAL CONVERTER TAOS117A FEBRUARY 2011 Detailed Description The TSL2571 light-to-digital device includes on-chip photodiodes, integrating amplifiers, ADCs, accumulators, 2 clocks, buffers, comparators, a state machine, and an I C interface. The device combines one photodiode (CH0), which is responsive to both visible and infrared light, and one photodiode (CH1), which is responsive primarily to infrared light. Two integrating ADCs simultaneously convert the amplified photodiode currents into 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. This digital output can be read by a microprocessor through which the illuminance (ambient light level) in lux is derived using an empirical formula to approximate the human eye response. 2 Communication to the device is accomplished through a fast (up to 400 kHz), two-wire I C serial bus for easy connection to a microcontroller or embedded controller. The digital output of the device is inherently more immune to noise when compared to an analog interface. The device 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 value. An interrupt is generated when the value of an ALS 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. Copyright 2011, TAOS Inc. The LUMENOLOGY Company 2 www.taosinc.com