t
TSL235
LIGHT TO FREQUENCY CONVERTER
t
TAOS003 鈥?MAY 1999
D
High-Resolution Conversion of Light
D
Intensity to Frequency With No External
Components
Communicates Directly With a
Microcontroller
Package
Single-Supply Operation Down to 2.7 V
Nonlinearity Error Typically 0.2% at 100 kHz
Stable 100 ppm/擄C Temperature Coefficient
Single-Supply Operation
SR PACKAGE
(FRONT VIEW)
D
Compact Three-Leaded Clear-Plastic
D
D
D
D
1
2
3
GND V
DD
OUT
Description
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 ultraviolet-
to-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 鈥?5擄C to 70擄C.
Functional Block Diagram
Light
Photodiode
Current-to-Frequency
Converter
Output
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)
鈥?/div>
Supply voltage, V
DD
(see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.5 V
Operating free-air temperature range, T
A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 鈥?5擄C to 70擄C
Storage temperature range, T
stg
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 鈥?5擄C to 85擄C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240擄C
鈥?/div>
Stresses beyond those listed under 鈥渁bsolute maximum ratings鈥?may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under 鈥渞ecommended operating conditions鈥?is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltage values are with respect to GND.
www.taosinc.com
Texas Advanced Optoelectronic Solutions Inc.
800 Jupiter Road, Suite 205
S
Plano, TX 75074
S
(972) 673-0759
t
t
Copyright
漏
2000, TAOS Inc.
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