ams AG - global leader in the design and manufacture of high performance analog ICs (integrated circuits)

TSL237T Light-to-Frequency

High-sensitivity converter low profile 4-lead package


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).

Key Features

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

Key Benefits

  • 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

Product Facts

Supply Voltage [V] 2,7-5,5
Responsivity [Hz/uW/cm²] 1200 @ 640
Output Frequency [Max.] 1 MHz
Selectable Sensitivity and Full-scale Output Frequency
Output Frequency Tolerances [+/- %] 20
Temperature Range [°C] -40 to 85
Packages T

Additional Information

  • Pulse oximetry
  • Color sensing
  • Turbidity sensing
  • Optical Switch