TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
1
The LUMENOLOGY r Company r
r
Copyright E 2007, TAOS Inc.
www.taosinc.com
DHigh-Resolution Conversion of Light
Intensity to Frequency With No External
Components
DCommunicates Directly With a
Microcontroller
DCompact Three-Leaded Clear-Plastic
Package
DSingle-Supply Operation Down to 2.7 V
DNonlinearity Error Typically 0.2% at 100 kHz
DStable 150 ppm/°C Temperature Coefficient
DSingle-Supply Operation
DRoHS Compliant (−LF Package Only)
Description
The TSL235R 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 TSL235R is characterized for operation over the temperature range of −25°C to 70°C and is supplied in
a 3-lead clear plastic side-looker package with an integral lens. When supplied in the lead (Pb) free package,
the device is RoHS compliant.
Functional Block Diagram
Light Current-to-Frequency
Converter
Photodiode Output
Available Options
DEVICE TAPACKAGE − LEADS PACKAGE DESIGNATOR ORDERING NUMBER
TSL235R −25°C to 70°C3-lead Sidelooker S TSL235R
TSL235R −25°C to 70°C3-lead Sidelooker—Lead (Pb) Free S TSL235R−LF
TSL235R −25°C to 70°C3-lead Surface-Mount Sidelooker—Lead (Pb) Free SM TSL235RSM−LF
Terminal Functions
TERMINAL
TYPE
DESCRIPTION
NAME NO. TYPE DESCRIPTION
GND 1 Power supply ground (substrate). All voltages are referenced to GND.
OUT 3 O Output frequency.
VDD 2Supply voltage.
r
r
Texas Advanced Optoelectronic Solutions Inc.
1001 Klein Road S Suite 300 S Plano, TX 75074 S (972) 673-0759
PACKAGE S
SIDELOOKER
(FRONT VIEW)
1
GND
2
VDD
3
OUT
PACKAGE SM
SURFACE MOUNT
SIDELOOKER
(FRONT VIEW)
1
GND
2
VDD
3
OUT
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
2
r
r
Copyright E 2007, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)†
Supply voltage, VDD (see Note 1) 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, TA −25°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, Tstg −25°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds (S Package) 260°C. . . . . . . . . . . . . . . . . . . .
Reflow solder, in accordance with J-STD-020C or J-STD-020D (SM Package) 260°C. . . . . . . . . . . . . . . . . . .
†Stresses beyond those listed under “absolute maximum ratings” 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 “recommended operating conditions” 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.
Recommended Operating Conditions
MIN NOM MAX UNIT
Supply voltage, VDD 2.7 5 5.5 V
Operating free-air temperature range, TA−25 70 °C
Electrical Characteristics at VDD = 5 V, TA = 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VOH High-level output voltage IOH = −4 mA 4 4.5 V
VOL Low-level output voltage IOL = 4 mA 0.25 0.4 V
IDD Supply current 2 3 mA
Full-scale frequency‡500 kHz
Temperature coefficient of output frequency Wavelength < 700nm ±150 ppm/°C
kSVS Supply-voltage sensitivity VDD = 5 V ±10% ±0.5 %/ V
‡Full-scale frequency is the maximum operating frequency of the device without saturation.
Operating Characteristics at VDD = 5 V, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
f
Output frequency
Ee = 430 μW/cm2, λp = 635 nm 200 250 300 kHz
fOOutput frequency Ee = 0 μW/cm20.4 10 Hz
Nli it
§
fO = 0 kHz to 10 kHz ±0.1% %F.S.
Nonlinearity §
fO = 0 kHz to 100 kHz ±0.2% %F.S.
Step response to full-scale step input 1 pulse of new
frequency plus 1 μs
‡Full-scale frequency is the maximum operating frequency of the device without saturation.
§Nonlinearity is defined as the deviation of fO from a straight line between zero and full scale, expressed as a percent of full scale.
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
3
The LUMENOLOGY r Company r
r
Copyright E 2007, TAOS Inc.
www.taosinc.com
TYPICAL CHARACTERISTICS
1
0.1
0.01
0.001
0.001 0.01 0.1 1 10
10
100
OUTPUT FREQUENCY
vs
IRRADIANCE
100 1 k
Ee − Irradiance − μW/cm2
VDD = 5 V
λp = 635 nm
TA = 25°C
1000
fO — Output Frequency — kHz
Figure 1 Figure 2
300 400 500 600 700 1000800 900 1100
λ − Wavelength − nm
Normalized Responsivity
0
0.2
0.4
0.6
0.8
1.0
1.2
PHOTODIODE SPECTRAL RESPONSIVITY
DARK FREQUENCY
vs
TEMPERATURE
VDD = 5 V
Ee = 0
TA − Temperature − °Cλ − Wavelength of Incident Light − nm
VDD = 5 V
TEMPERATURE COEFFICIENT
OF OUTPUT FREQUENCY
vs
WAVELENGTH OF INCIDENT LIGHT
−25 0 25 50 75
0
0.2
0.4
0.6
0.8
1
1.2
0
1000
2000
3000
4000
5000
6000
7000
300 400 500 600 700 1000800 900
Temperature Coefficient of Output Frequency — ppm/5C
fO(dark) — Dark Frequency — Hz
Figure 3 Figure 4
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
4
r
r
Copyright E 2007, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
TYPICAL CHARACTERISTICS
OUTPUT FREQUENCY
vs
SUPPLY VOLTAGE
VDD − Supply Voltage − V
Normalized Output Frequency
2.5 3 3.5 4 4.5 5
0.980
0.985
0.990
0.995
1.000
1.005
1.010
5.5
TA = 25°C
fO = 250 kHz
Figure 5
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
5
The LUMENOLOGY r Company r
r
Copyright E 2007, TAOS Inc.
www.taosinc.com
APPLICATION INFORMATION
Power-supply considerations
Power-supply lines must be decoupled by a 0.01-μF to 0.1-μF capacitor with short leads placed close to the
TSL235R (Figure 6).
Output interface
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.
Measuring the frequency
The choice of interface and measurement technique depends on the desired resolution and data-acquisition
rate. For maximum data-acquisition rate, period-measurement techniques are used.
Period measurement requires the use of a fast reference clock with available resolution directly related to
reference-clock rate. The technique is employed to measure rapidly varying light levels or to make a fast
measurement of a constant light source.
Maximum resolution and accuracy may be obtained using frequency-measurement, pulse-accumulation,
or integration techniques. Frequency measurements provide the added benefit of averaging out random- or
high-frequency variations (jitter) resulting from noise in the light signal. Resolution is limited mainly by available
counter registers and allowable measurement time. Frequency measurement is well suited for slowly varying
or constant light levels and for reading average light levels over short periods of time. Integration, the
accumulation of pulses over a very long period of time, can be used to measure exposure — the amount of light
present in an area over a given time period.
TSL235R Timer / Port
MCU
0.1 μF
VDD
2
3
1
Figure 6. Typical TSL235R Interface to a Microcontroller
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
6
r
r
Copyright E 2007, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
APPLICATION INFORMATION
PCB Pad Layout
Suggested PCB pad layout guidelines for the SM surface mount package are shown in Figure 7.
3.2
1.0 1.0 1.0
1.01.0
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
Figure 7. Suggested SM Package PCB Layout
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
7
The LUMENOLOGY r Company r
r
Copyright E 2007, TAOS Inc.
www.taosinc.com
MECHANICAL DATA
The device is supplied in a clear plastic three-lead through-hole sidelooker package (S).
PACKAGE S PLASTIC SINGLE-IN-LINE SIDE-LOOKER PACKAGE
1.642.60
2.30
4.60
R 0.90
1.80
0.42
1
2y 2
0.47 TYP
TOP VIEW
SIDE VIEWFRONT VIEW
0.42
1.56
14.86 + 0.50
4.60
0.15
Note B
Lead Free
Available
Pb
NOTES: A. All linear dimensions are in millimeters; tolerance is ± 0.25 mm unless otherwise stated.
B. Dimension is to center of lens arc, which is located below the package face.
C. The integrated photodiode active area is typically 0.92 mm2 in size and is located in the center of the lens and 0.97 mm below the
top of the lens surface.
D. Index of refraction of clear plastic is 1.55.
E. Lead finish for TSL235R: solder dipped, 63% Sn/37% Pb. Lead finish for TSL235R−LF: solder dipped, 100% Sn.
F. This drawing is subject to change without notice.
Figure 8. Package S — Single-In-Line Side-Looker Package Configuration
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
8
r
r
Copyright E 2007, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
MECHANICAL DATA
PACKAGE SM PLASTIC SURFACE MOUNT SIDE-LOOKER PACKAGE
1.642.60
2.30
4.60
R 0.90
1.80
0.42
1.00
0.47 TYP
TOP VIEW
SIDE VIEWFRONT VIEW
0.42
5.73 + 0.50
4.60
0.15 Note B
2.59
0.62 + 0.10 1.97
0.62 +0.10
−0.15
Lead Free
Pb
2y 2
NOTES: A. All linear dimensions are in millimeters; tolerance is ± 0.25 mm unless otherwise stated.
B. Dimension is to center of lens arc, which is located below the package face.
C. The integrated photodiode active area is typically located in the center of the lens and 0.97 mm below the top of the lens surface.
D. Index of refraction of clear plastic is 1.55.
E. Lead finish for TSL235RSM−LF: solder dipped, 100% Sn.
F. This drawing is subject to change without notice.
Figure 9. Package SM — Surface Mount Side-Looker Package Configuration
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
9
The LUMENOLOGY r Company r
r
Copyright E 2007, TAOS Inc.
www.taosinc.com
PRODUCTION DATA — information in this document is current at publication date. Products conform to
specifications in accordance with the terms of Texas Advanced Optoelectronic Solutions, Inc. standard
warranty. Production processing does not necessarily include testing of all parameters.
LEAD-FREE (Pb-FREE) and GREEN STATEMENT
Pb-Free (RoHS) TAOS’ terms Lead-Free or Pb-Free mean semiconductor products that are compatible with the current
RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous
materials. Where designed to be soldered at high temperatures, TAOS Pb-Free products are suitable for use in specified
lead-free processes.
Green (RoHS & no Sb/Br) TAOS defines Green to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and
Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material).
Important Information and Disclaimer The information provided in this statement represents TAOS’ knowledge and
belief as of the date that it is provided. TAOS bases its knowledge and belief on information provided by third parties,
and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate
information from third parties. TAOS has taken and continues to take reasonable steps to provide representative
and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and
chemicals. TAOS and TAOS suppliers consider certain information to be proprietary, and thus CAS numbers and other
limited information may not be available for release.
NOTICE
Texas Advanced Optoelectronic Solutions, Inc. (TAOS) reserves the right to make changes to the products contained in this
document to improve performance or for any other purpose, or to discontinue them without notice. Customers are advised
to contact TAOS to obtain the latest product information before placing orders or designing TAOS products into systems.
TAOS assumes no responsibility for the use of any products or circuits described in this document or customer product
design, conveys no license, either expressed or implied, under any patent or other right, and makes no representation that
the circuits are free of patent infringement. TAOS further makes no claim as to the suitability of its products for any particular
purpose, nor does TAOS assume any liability arising out of the use of any product or circuit, and specifically disclaims any
and all liability, including without limitation consequential or incidental damages.
TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS, INC. PRODUCTS ARE NOT DESIGNED OR INTENDED FOR
USE IN CRITICAL APPLICATIONS IN WHICH THE FAILURE OR MALFUNCTION OF THE TAOS PRODUCT MAY
RESULT IN PERSONAL INJURY OR DEATH. USE OF TAOS PRODUCTS IN LIFE SUPPORT SYSTEMS IS EXPRESSLY
UNAUTHORIZED AND ANY SUCH USE BY A CUSTOMER IS COMPLETELY AT THE CUSTOMER’S RISK.
LUMENOLOGY, TAOS, the TAOS logo, and Texas Advanced Optoelectronic Solutions are registered trademarks of Texas Advanced
Optoelectronic Solutions Incorporated.
TSL235R
LIGHT-TO-FREQUENCY CONVERTER
TAOS038E −SEPTEMBER 2007
10
r
r
Copyright E 2007, TAOS Inc. The LUMENOLOGY r Company
www.taosinc.com
