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부품번호 | TSL238T 기능 |
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기능 | HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER | ||
제조업체 | TAOS | ||
로고 | |||
전체 12 페이지수
r
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D High-Resolution Conversion of Light
Intensity to Frequency With No External
Components
D High Irradiance Responsivity . . .
3.4 kHz/(mW/cm2) at λp = 640 nm
D Low Dark Frequency . . . < 6 Hz at 505 C
D Single-Supply Operation . . . 2.7 V to 5.5 V
D Stable 200 ppm/°C Temperature Coefficient
D Interfaces Directly to a Microcontroller
D Lead (Pb) Free Package
D RoHS Compliant
TSL238T
HIGH-SENSITIVITY
LIGHT-TO-FREQUENCY CONVERTER
TAOS080G − DECEMBER 2007
PACKAGE T
4-LEAD SMD
(TOP VIEW)
OE 1
4 OUT
GND 2
3 VDD
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. 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 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
Light
Photodiode
Current-to-Frequency
Converter
Output
Available Options
DEVICE
TSL238T
TA
−40°C to 85°C
PACKAGE − LEADS
4-lead Low Profile Surface Mount
PACKAGE DESIGNATOR ORDERING NUMBER
T TSL238T
Terminal Functions
TERMINAL
NAME
T PKG
NO.
GND
2
OE 1
OUT
4
VDD
3
TYPE
I
O
DESCRIPTION
Power supply ground (substrate). All voltages are referenced to GND.
Enable for fO (active low).
Output frequency.
Supply voltage.
The
LUMENOLOGY
r
Company
Texas
Advarnced
Optoelectronic
Solutions
Inc.
1001 Klein Road S Suite 300 S Plano, TX 75074 S (972r) 673-0759
www.taosinc.com
Copyright E 2007, TAOS Inc.
1
TSL238T
HIGH-SENSITIVITY
LIGHT-TO-FREQUENCY CONVERTER
TAOS080G − DECEMBER 2007
TYPICAL CHARACTERISTICS
1000
100
OUTPUT FREQUENCY
vs
IRRADIANCE
VDD = 5 V
λp = 640 nm
TA = 25°C
PHOTODIODE SPECTRAL RESPONSIVITY
1
0.8
10
0.6
1
0.4
0.1
0.01 0.2
0.001
0.001
0.01 0.1
1
10 10 0
Ee − Irradiance − μW/cm2
Figure 1
1k
SUPPLY CURRENT
vs.
FREE-AIR TEMPERATURE
1.6
1.4
1.2
1
0.8
0.6
−40
−15 10 35 60
TA − Free-Air Temperature − °C
Figure 3
85
0300 400
500 600 700 800 900 1000 1100
λ − Wavelength − nm
Figure 2
OUTPUT FREQUENCY
vs.
FREE-AIR TEMPERATURE
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
−25
0 25 50
TA − Free-Air Temperature − °C
Figure 4
75
Copyright E 2007, TAOS Inc.
4
r
www.taosinc.com
The LUMENOLOGY r Company
r
4페이지 TSL238T
HIGH-SENSITIVITY
LIGHT-TO-FREQUENCY CONVERTER
TAOS080G − DECEMBER 2007
APPLICATION INFORMATION
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 the
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.
Output enable (OE) places the output in a high-impedance state for multiple-unit sharing of a microcontroller
input line. When the OE line goes low, the device resynchronizes the output to an integration cycle. The rising
edge of the output signal (OUT) will occur exactly one period of the output frequency after OE goes low.
PCB Pad Layout
Suggested PCB pad layout guidelines for the T package are shown in Figure 10.
2.90
1.50
1.00 0.90
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
Figure 10. Suggested T Package PCB Layout
The LUMENOLOGY r Company
r
www.taosinc.com
r
Copyright E 2007, TAOS Inc.
7
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부품번호 | 상세설명 및 기능 | 제조사 |
TSL238 | HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER | TAOS |
TSL238T | HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER | TAOS |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |