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

TSL238T Light-to-Frequency

High-sensitivity converter low profile 4-pin package


The TSL238T 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 TSL238T is characterized for operation over the temperature range of −40°C to 85°C and is supplied in a compact 4-lead surface-mount package that is lead (Pb) free and RoHS compliant.

Key Features

  • 850K:1 input dynamic range
  • Low dark frequency of 0.6 Hz (Typ)
  • 2.6mm x 3.8mm 4-lead SMD (T) package

Key Benefits

  • Detects light intensity at a high resolution
  • Provides low light level operation 
  • Reduces board space requirements while simplifying designs

Product Facts

Supply Voltage [V] 2,7-5,5
Responsivity [Hz/uW/cm²] 3400 @ 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
  • Turbidity sensing
  • Optical Switch