TAOS TSL245 Datasheet
TSL245
INFRARED LIGHTTOFREQUENCY CONVERTER
TAOS005 – MAY 1999
High-Resolution Conversion of Light
Intensity to Frequency With No External
SR PACKAGE
(FRONT VIEW)
Components
Communicates Directly With a
Microcontroller
Compact Three-Leaded Plastic Package
321
Single-Supply Operation Down to 2.7 V
Nonlinearity Error Typically 0.2% at 100 kHz
Integral Visible-Light Cutoff Filter
Description
GND
The TSL245 infrared 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 the output is TTL compatible, it allows direct interface to a
microcontroller or other logic circuitry. The device responds over the infrared light range of 800 nm to 1100 nm and
is characterized for operation over the temperature range of –25°C to 70°C.
DD
OUTV
Functional Block Diagram
Light
Photodiode Output
Current-to-Frequency
Converter
Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)
Supply voltage, VDD (see Note 1) 6.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, TA –25°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
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.
–25°C to 85°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
stg
†
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Texas Advanced Optoelectronic Solutions Inc.
800 Jupiter Road, Suite 205 Plano, TX 75074 (972) 673-0759
Copyright 2000, TAOS Inc.
1
TSL245
INFRARED LIGHTTOFREQUENCY CONVERTER
TAOS005 – MAY 1999
Recommended Operating Conditions
MIN NOM MAX UNIT
Supply voltage, V
Operating free-air temperature range, T
DD
A
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 4.3 V
Low-level output voltage IOL = 4 mA 0.17 0.26 V
Supply current 2 3 mA
Full-scale frequency
‡
Supply-voltage sensitivity VDD = 5 V ±10% 0.5 %/V
Operating Characteristics at VDD = 5 V, TA = 25°C
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
fOOutput frequency
p
Nonlinearity
§
Step response to full-scale step input
‡
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.
Ee = 920 µW/cm2, λp = 940 nm 200 250 300 kHz
Ee = 0 0.25 10 Hz
f
= 0 kHz to 10 kHz ±0.1% %F.S.
O
f
= 0 kHz to 100 kHz ±0.2% %F.S.
O
2.7 5 6 V
–25 70 °C
500 kHz
1 pulse of new
frequency plus 1 µs
2
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1000
100
VDD = 5 V
λp = 940 nm
TA = 25°C
TYPICAL CHARACTERISTICS
OUTPUT FREQUENCY
vs
IRRADIANCE
TSL245
INFRARED LIGHTTOFREQUENCY CONVERTER
TAOS005 – MAY 1999
PHOTODIODE SPECTRAL RESPONSIVITY
1
TA = 25°C
0.9
0.8
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 Figure 2
DARK FREQUENCY
vs
TEMPERATURE
100
VDD = 5 V
Ee = 0
10
100 1 k
2
0.7
0.6
0.5
0.4
0.3
Normalized Responsivity
0.2
0.1
0
600 700 800 900
λ – Wavelength – nm
TEMPERATURE COEFFICIENT
OF OUTPUT FREQUENCY
C
10000
8000
WAVELENGTH OF INCIDENT LIGHT
VDD = 5 V
TA = 25°C to 70°C
1000 1100
vs
1
– Dark Frequency – Hzf
0.1
O(dark)
0.01
– 25 0 25 50
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6000
4000
2000
75
TA – Temperature – °C
0
Temperature Coefficient of Output Frequency – ppm/°
700 800 900 1000
750 850 950
λ – Wavelength of Incident Light – nm
Figure 3 Figure 4
3
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