The TSL237 light-to-frequency converter combines a silicon photodiode and a current-to-frequency converter on a single monolithic CMOS integrated circuit. The output is a square wave (50% duty cycle) with frequency directly proportional to light intensity. Because it is TTL compatible, the 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.
Communicates directly with a microcontroller
Compact 3-lead clear plastic package
High-resolution conversion of light intensity to frequency with no external components
Nonlinearity Error (Typically 0.2% at 100 kHz)
Stable 150ppm/° C Temperature Coefficient
Supply Voltage 2.7 - 5.5 VDC
Operating Temperature range -25 - 70 C
Typical current draw 2 mA
Output Frequency 200 - 300 kHz
Note: Power-supply lines must be decoupled by a 0.01 µF to 0.1 µF capacitor with short leads placed close to the TSL237R. 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.