1980 Adafruit

TSL2591 Datasheet - Apr. 2013 - ams163.5 The TSL2591 is a very-high sensitivity light-to-digital converter General Description that transforms light intensity into a digital signal output 2 capable of direct I C interface. The device combines one broadband photodiode (visible plus infrared) and one infrared-responding photodiode on a single CMOS integrated circuit. Two integrating ADCs convert the photodiode currents into a digital output that represents the irradiance measured on each channel. This digital output can be input to a microprocessor where illuminance (ambient light level) in lux is derived using an empirical formula to approximate the human eye response. The TSL2591 supports a traditional level style interrupt that remains asserted until the firmware clears it. Figure TSL2591 1: Key Benefits and Features Benefits Features Approximates Human Eye Response Dual Diode Flexible Operation Programmable Analog Gain and Integration Time Suited for Operation Behind Dark Glass 600M:1 Dynamic Range Two Internal Interrupt Sources Low Operating Overhead Programmable Upper and Lower Thresholds One Interrupt Includes Programmable Persistence Filter Low Power 3.0 A Sleep State User Selectable Sleep Mode Data Rates up to 400 kbit/s 2 I C Fast Mode Compatible Interface Input Voltage Levels Compatible with 3.0V Bus Datasheet - Apr. 2013 - ams163.5 TSL2591 1Figure TSL2591 2: Block Diagram The TSL2591 contains two integrating analog-to-digital Detailed Description converters (ADC) that integrate currents from two photodiodes. Integration of both channels occurs simultaneously. Upon completion of the conversion cycle, the conversion result is transferred to the Channel 0 and Channel 1 data registers, respectively. The transfers are double-buffered to ensure that the integrity of the data is maintained. After the transfer, the device automatically begins the next integration cycle. Communication with the device is accomplished through a 2 standard, two-wire I C serial bus. Consequently, the TSL2591 can be easily connected to a microcontroller or embedded controller. No external circuitry is required for signal conditioning. Because the output of the device is digital, the output is effectively immune to noise when compared to an analog signal. The TSL2591 also supports an interrupt feature that simplifies and improves system efficiency by eliminating the need to poll a sensor for a light intensity value. The primary purpose of the interrupt function is to detect a meaningful change in light intensity. The concept of a meaningful change can be defined by the user both in terms of light intensity and time, or persistence, of that change in intensity. The device has the ability to define two sets of thresholds, both above and below the current light level. An interrupt is generated when the value of a conversion exceeds either of these limits. One set of thresholds can be configured to trigger an interrupt only when the ambient light exceeds them for a configurable amount of time (persistence) while the other set can be configured to trigger an immediate interrupt. TSL2591 2 Datasheet - Apr. 2013 - ams163.5