ams – TSL2591: Low Light, Sensitive Digital Light Sensor



The TSL2591 is a very high sensitivity light-to-digital converter that transforms light intensity into a digital signal output capable of direct I2C 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.


  • Dual diode
  • Programmable analog gain and integration time
  • 600M:1 dynamic range
  • Two internal interrupt sources
  • Programmable upper and lower thresholds
  • One interrupt includes programmable persistence filter
  • User selectable sleep mode
  • Data rates up to 400kbit/s
  • Input voltage levels compatible with 3.0V Bus

  • Ambient light sensing (ALS) for mobile handsets, tablets, notebooks, TVs and monitors
  • Digital signage
  • White goods
  • Medical and industrial instrumentation
  • Keyboard illumination control
  • Solid state and general lighting control
  • Printer paper detection


  • Design flexibility for dark glass and placement
  • Enables operation in IR light environments
  • Enables dark room to sunlight operation
  • Reduces microprocessor interrupt overhead
  • Improves lux accuracy across various light sources
  • Reduces board space requirements while simplifying designs