r
r
TSL238T
HIGH-SENSITIVITY
LIGHT-TO-FREQUENCY CONVERTER
TAOS080E
−
JUNE 2007
D
High-Resolution Conversion of Light
D
D
D
D
D
D
D
Intensity to Frequency With No External
Components
High Irradiance Responsivity . . .
3.4 kHz/(mW/cm
2
) at
λ
p
= 640 nm
Low Dark Frequency . . . < 6 Hz at 505 C
Single-Supply Operation . . . 2.7 V to 5.5 V
Stable 200 ppm/°C Temperature Coefficient
Interfaces Directly to a Microcontroller
Lead (Pb) Free Package
RoHS Compliant
PACKAGE T
4-LEAD SMD
(TOP VIEW)
OE 1
GND 2
4 OUT
3 V
DD
Description
The TSL238T 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. 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 TSL238T 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 that is lead (Pb) free and RoHS compliant.
Functional Block Diagram
Current-to-Frequency
Converter
Light
Photodiode
Output
Available Options
DEVICE
TSL238T
T
A
−40°C
to 85°C
PACKAGE
−
LEADS
4-lead Low Profile Surface Mount
PACKAGE DESIGNATOR
T
ORDERING NUMBER
TSL238T
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
1
r
Copyright
E
2007, TAOS Inc.