The TSL235R-LF 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. Because it is TTL compatible, the digital output allows direct interface to a microcontroller or other logic circuitry. 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 TSL235R is characterized for operation over the temperature range of −25°C to +70°C and is supplied in a 3-lead clear plastic side-looker package with an integral lens.
Light-to-Frequency Converter Features
Note: Power-supply lines must be decoupled by a 0.01 µF to 0.1 µF capacitor with short leads placed close to the TSL235R. The output of the device is designed to drive a standard TTL or CMOS logic input over short distances. If lines greater than 12 inches are used on the output, a buffer or line driver is recommended.
- High-resolution conversion of light intensity to frequency with no external components
- Communicates directly With a microcontroller
- Compact three-lead clear plastic package
- Single-supply operation from 2.7V to 5.5V DC
- Typical current draw: 2 mA
- Output frequency: 200 to 300 kHz
- Nonlinearity error typically 0.2% at 100 kHz
- Stable 150 ppm/°C temperature coefficient
- Operating Temperature: -25 to +70 °C
Light-to-Frequency Converter Resources