ams TSL237T Light-to-Frequency



The TSL237 light-to-frequency converter combines a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit. Output is a square wave (50% duty cycle) with frequency directly proportional to light intensity (irradiance) on the photodiode. The digital output allows direct interface to a microcontroller or other logic circuitry. Output enable (OE) places the output in a high-impedance state for multiple-unit sharing of a microcontroller input line. The device has been temperature compensated for the ultraviolet-to-visible light range of 320 nm to 700 nm and responds over the light range of 320 nm to 1050 nm. The TSL237 is characterized for operation over the temperature range of −40°C to 85°C and is supplied in a 4-lead ChipLED package (CL) and a compact 4-lead surface-mount package (T).



  • 5M:1 input dynamic range
  • Low dark frequency (0.1Hz typical)
  • High irradiance responsivity 1.2kHz/(µW/cm2) @ λp = 640nm
  • 2.6mm x 3.8mm 4-lead SMD (T) package


  • Detects light intensity at a high resolution
  • Provides low light level operation
  • Provides for high sensitivity to detect a small change in light
  • Reduces board space requirements while simplifying designs


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TSL237T DS000129


Application note

Environmental documents

Lifecycle documents