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TSL237T
HIGH-SENSITIVITY
LIGHT-TO-FREQUENCY CONVERTER
TAOS055G
−
JUNE 2007
D
High-Resolution Conversion of Light
D
D
D
D
D
D
Intensity to Frequency With No External
Components
High Irradiance Responsivity . . .
1.2 kHz/(mW/cm
2
) at
λ
p
= 640 nm
Low Dark Frequency . . . < 2 Hz at 505 C
Single-Supply Operation . . . 2.7 V to 5.5 V
Stable 200 ppm/°C Temperature Coefficient
Communicates Directly with a
Microcontroller
RoHS Compliant
PACKAGE T
4-LEAD SMD
(TOP VIEW)
OE 1
GND 2
4 OUT
3 V
DD
Description
The TSL237T 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 TSL237T 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.
Functional Block Diagram
Current-to-Frequency
Converter
Light
Photodiode
Output
OE
Available Options
DEVICE
TSL237T
T
A
−40°C
to 85°
PACKAGE
−
LEADS
4-lead Low Profile Surface Mount
PACKAGE DESIGNATOR
T
ORDERING NUMBER
TSL237T
Terminal Functions
TERMINAL
NAME
GND
OE
OUT
V
DD
T PKG
NO.
2
1
4
3
I
O
TYPE
DESCRIPTION
Power supply ground (substrate). All voltages are referenced to GND.
Enable for f
O
(active low).
Output frequency.
Supply voltage.
The
LUMENOLOGY
r
Company
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road
S
Suite 300
S
Plano, TX 75074
S
(972) 673-0759
r
www.taosinc.com
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Copyright
E
2007, TAOS Inc.
TAOS [ TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS ]
