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TSL235R
Datasheet (TAOS)
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Datasheet TSL235R Datasheet (TAOS)

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Page 1
TSL235R
LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
High-Resolution Conversion of Light
Intensity to Frequency With No External
PACKAGE
(FRONT VIEW)
Components
Communicates Directly With a
Microcontroller
Compact Three-Leaded Clear-Plastic
321
Package
Single-Supply Operation Down to 2.7 V Nonlinearity Error Typically 0.2% at 100 kHz Stable 150 ppm/°C Temperature Coefficient Single-Supply Operation
GND
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.
DD
OUTV
Functional Block Diagram
The
LUMENOLOGY
Light
Company
Photodiode Output
Texas Advanced Optoelectronic Solutions Inc.
800 Jupiter Road, Suite 205 Plano, TX 75074 (972) 673-0759
Current-to-Frequency
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Converter
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TSL235R LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
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, T
–25°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
stg
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 240°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, V Operating free-air temperature range, T
DD
A
2.7 5 5.5 V
–25 70 °C
Electrical Characteristics at VDD = 5 V, TA = 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
OH
V
OL
I
DD
k
SVS
‡
Full-scale frequency is the maximum operating frequency of the device without saturation.
High-level output voltage IOH = –4 mA 4 4.5 V Low-level output voltage IOL = 4 mA 0.25 0.4 V Supply current 2 3 mA Full-scale frequency Temperature coefficient of output frequency Wavelength < 700nm ±150 ppm/°C Supply-voltage sensitivity VDD = 5 V ±10% ±0.5 %/V
‡
500 kHz
†
Operating Characteristics at VDD = 5 V, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
fOOutput frequency
‡
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.
p
Nonlinearity
Step response to full-scale step input
§
Ee = 430 µW/cm2, λp = 635 nm 200 250 300 kHz Ee = 0 µW/cm
f
= 0 kHz to 10 kHz ±0.1% %F.S.
O
f
= 0 kHz to 100 kHz ±0.2% %F.S.
O
2
frequency plus 1 µs
0.4 10 Hz
1 pulse of new
2
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Page 3
1000
100
VDD = 5 V
λp = 635 nm
TA = 25°C
TYPICAL CHARACTERISTICS
OUTPUT FREQUENCY
vs
IRRADIANCE
TSL235R
LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
PHOTODIODE SPECTRAL RESPONSIVITY
1.2
1.0
10
1
0.1
— Output Frequency — kHz
O
f
0.01
0.001
0.001 0.01 0.1 1 10 Ee – Irradiance – µW/cm
Figure 1
DARK FREQUENCY
vs
TEMPERATURE
1.2 VDD = 5 V
Ee = 0
1
100 1 k
2
0.8
0.6
0.4
Normalized Responsivity
0.2
0
300 400 500 600 700 1000800 900 1100
λ – Wavelength – nm
Figure 2
TEMPERATURE COEFFICIENT
OF OUTPUT FREQUENCY
vs
WAVELENGTH OF INCIDENT LIGHT
7000
VDD = 5 V
6000
0.8
0.6
0.4
— Dark Frequency — Hz
O(dark)
f
0.2
0
–25 0 25 50 75
The
LUMENOLOGY
TA – Temperature – °C
Figure 3
Company
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5000
4000
3000
2000
1000
0
Temperature Coefficient of Output Frequency — ppm/C
300 400 500 600 700 1000800 900
λ – Wavelength of Incident Light – nm
Figure 4
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TSL235R LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
TYPICAL CHARACTERISTICS
1.010
1.005
1.000
0.995
0.990
Normalized Output Frequency
0.985
TA = 25°C fO = 250 kHz
OUTPUT FREQUENCY
vs
SUPPLY VOLTAGE
0.980
2.5 3 3.5 4 4.5 5 VDD – Supply Voltage – V
Figure 5
5.5
4
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Page 5
LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
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.
TSL235R
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.
V
DD
2
0.1 µF
TSL235R Timer/Port
3
1
MCU
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LUMENOLOGY
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Figure 6. Typical TSL235R Interface to a Microcontroller
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TSL235R LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
MECHANICAL DATA
The device is supplied in a clear plastic three-lead package.
0.189 (4,80)
0.173 (4,40)
0.165 (4,20)
0.150 (3,80)
0.071 (1,80)
0.110 (2,80)
0.016 (0,40)
PLASTIC SINGLE-IN-LINE PACKAGE
0.072 (1,84)
0.057 (1,44)
0.032 (0,80)
0.016 (0,40)
R 0.035 (0,90)
0.071 (1,8)
0.189 (4,80)
0.173 (4,40)
0.079 (2,00)
0.039 (1,00)
0.027 (0,70)
0.079 (2,00)
0.026 (0,65)
0.018 (0,45)
0.079 (2,00)
Figure 7. Package Configuration
NOTES: A. All linear dimensions are in inches (millimeters).
B. This drawing is subject to change without notice. C. All dimensions apply before solder dip. D. Package body is a clear nonfilled optically transparent material E. Index of refraction of clear plastic is 1.55.
0.029 (0,75)
0.102 (2,6)
0.630 (16,00)
0.531 (13,50)
0.018 (0,45)
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Page 7
TSL235R
LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
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.
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 RESUL T I N PERSONAL INJURY OR D EATH. 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 is a registered trademark, and TAOS, the TAOS logo, and Texas Advanced Optoelectronic Solutions are trademarks of Texas Advanced Optoelectronic Solutions Incorporated.
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TSL235R LIGHTTOFREQUENCY CONVERTER
TAOS038 – APRIL 2002
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