26 Apr 2013 The new TSL2591 family of digital light sensors from ams offers low-light sensitivity down to 0.000377 lux.
With a wide 600M:1 dynamic range up to 88,000 lux (bright sunlight), the TSL2591 device family increases design flexibility and offers engineers new levels of performance in ambient light sensors for displays and other applications.
Designs using lower-sensitivity light sensors face severe constraints due to the properties of the attenuating material they are placed behind, the physical placement of the sensor, and the minimum intensity of light required in order to deliver sufficiently accurate measurements.
Available from Pacer, the TSL2591 devices can deliver accurate and meaningful measurements even when exposed to extremely low light levels. Thus the sensor can be placed away from the direct path of the light it is measuring and behind a wider variety of darkened glass or attenuating materials. The devices provide an interrupt feature that simplifies and improves system efficiency by eliminating the need to poll a sensor for a light intensity value, as the primary purpose of the interrupt function is to detect a meaningful change in light intensity. Meaningful change can be defined by the user in terms of light intensity and time, or the persistence of a change in intensity. The TSL2591 is a fully integrated light-to-digital sensor with dual analog-to-digital converters and an I2C interface. It offers programmable gain and programmable integration time.
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.
For display applications, the sensor exhibits a photopic response to ambient light intensity that mimics the human eye. Its ultra-high sensitivity reduces or eliminates design concerns for smartphone and tablet displays in which inked glass variations can result in costly design alterations to accommodate less sensitive devices. The TSL2591 can be placed deeper within the end product, providing more efficient and lower-cost solutions, and also provides for a sleek, seamless industrial design with no unsightly apertures or voids in inked glass.
For full details visit Pacer's website:
http://www.pacer.co.uk/products/sensors/smartlightandcoloursensors/lighttodigital/
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