LIGHTTOFREQUENCY CONVERTER
t
t
D High-Resolution Conversion of Light
Intensity to Frequency With No External Components
D Communicates Directly Wit...
Description
t
t
D High-Resolution Conversion of Light
Intensity to Frequency With No External Components
D Communicates Directly With a
Microcontroller
D Compact Three-Leaded Clear-Plastic
Package
D Single-Supply Operation Down to 2.7 V D Nonlinearity Error Typically 0.2% at 100 kHz D Stable 100 ppm/°C Temperature Coefficient D Single-Supply Operation
TSL235 LIGHTĆTOĆFREQUENCY CONVERTER
SR PACKAGE (FRONT VIEW)
TAOS003 – MAY 1999
1 23
Description
GND VDD OUT
The TSL235 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 ultravioletto-visible light range of 300 nm to 700 nm and responds over the light range of 300 nm to 1100 nm. The TSL235 is characterized for operation over the temperature range of –25°C to 70°C.
Functional Block Diagram
Light
Photodiode
Current-to-Frequency Converter
Output
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VDD (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . ....
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