TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER r r TAOS080G - DECEMBER 2007 D High-Resolution Conversion of Light PACKAGE T 4-LEAD SMD (TOP VIEW) Intensity to Frequency With No External Components High Irradiance Responsivity . . . 3.4 kHz/(mW/cm2) at p = 640 nm Low Dark Frequency . . . < 6 Hz at 50 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 D D D D D D D 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 -40C to 85C and is supplied in a compact 4-lead surface-mount package that is lead (Pb) free and RoHS compliant. Functional Block Diagram Light Current-to-Frequency Converter Photodiode Output Available Options DEVICE TSL238T TA -40C to 85C PACKAGE - LEADS PACKAGE DESIGNATOR 4-lead Low Profile Surface Mount T ORDERING NUMBER TSL238T Terminal Functions TERMINAL NAME T PKG NO. TYPE GND 2 OE 1 I OUT 4 O VDD 3 DESCRIPTION Power supply ground (substrate). All voltages are referenced to GND. Enable for fO (active low). Output frequency. Supply voltage. The LUMENOLOGY r Company Copyright E 2007, TAOS Inc. r Texas Advanced Optoelectronic Solutions Inc. 1001 Klein Road S Suite 300 S Plano, TX 75074 S (972) r 673-0759 www.taosinc.com 1 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) Supply voltage, VDD (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V Input voltage range, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to VDD +0.3 V Output current, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 mA Short circuit of output to ground duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 s Operating free-air temperature range, TA (see Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40C to 85C Storage temperature range, Tstg (see Note 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40C to 85C Solder conditions in accordance with JEDEC, J-STD-020C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260C 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. NOTES: 1. All voltage values are with respect to GND. 2. Long-term storage or operation above 70C could cause package yellowing that will lower the sensitivity to wavelengths < 500nm. Recommended Operating Conditions Supply voltage, VDD High-level input voltage, VIH MIN NOM 2.7 5 MAX UNIT 5.5 V 0.8 x VDD VDD V 0 0.5 V -40 70 C Low-level input voltage, VIL Operating free-air temperature range, TA Electrical Characteristics at VDD = 5 V, TA = 25C, p = 640 nm (Note 1) (unless otherwise noted) PARAMETER TEST CONDITIONS MIN VOH High-level output voltage IOH = - 1 mA VOL Low-level output voltage IOL = 1 mA IIH High-level input current IIH Low-level input current IDD Supply current Ee = 14.7 W/cm2 Full-scale frequency (Note 2) TA = 50C (Note 3) Temperature coefficient of responsivity Wavelength < 600nm, fO = 50 kHz VDD = 5 V 10% kSVS Supply-voltage sensitivity 4 TYP MAX 4.5 0.25 UNIT V 0.4 V -10 10 A -10 10 A 3 mA 2 500 1000 kHz 200 ppm/C 0.5 %/ V NOTES: 1. The input irradiance is supplied with red LED light source with peak wavelength = 640 nm. 2. Full-scale frequency is the maximum frequency of the device without saturation. Higher irradiance will not result in any additional increase of output frequency. The output frequency will remain at approximately the saturation frequency to a minimum of 1000 W/sq-cm 640-nm irradiance. During production testing, devices are not tested at this very high irradiance level. 3. Measured at wafer probe using 50C hot chuck. Copyright E 2007, TAOS Inc. 2 The LUMENOLOGY r Company r www.taosinc.com r TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 Operating Characteristics at VDD = 5 V, TA = 25C, p = 640 nm (unless otherwise noted) PARAMETER fO fD TEST CONDITIONS Output frequency Ee = 14.7 W/cm2 Ee = 0 W/cm2 Dark frequency Ee = 0 W/cm2, TA = 50C (Note 1) MIN TYP MAX 40 50 60 0 0.3 0 UNIT kHz Hz 6 Hz Re Irradiance responsivity 3.4 kHz/(W/ cm2) p Peak response wavelength 700 nm 1% % F.S. fO = 0 kHz to 10 kHz Nonlinearity (Note 2) Step response to full-scale step input 1 pulse of new frequency plus 1 s Time from OE low to output enabled 1 period of output frequency NOTES: 1. Measured at wafer probe using 50C hot chuck. 2. Nonlinearity is defined as the deviation from a straight line between zero and maximum of stated range, expressed as a percent of stated range. The LUMENOLOGY r Company Copyright E 2007, TAOS Inc. r www.taosinc.com r 3 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 TYPICAL CHARACTERISTICS OUTPUT FREQUENCY vs IRRADIANCE PHOTODIODE SPECTRAL RESPONSIVITY 1 100 VDD = 5 V p = 640 nm TA = 25C 0.8 Normalized Responsivity Output Frequency (fO - fD) -- kHz 1000 10 1 0.1 0.4 0.2 0.01 0.001 0.001 0.6 0.01 0.1 1 Ee - Irradiance - 10 10 0 0 1k 300 400 500 W/cm2 900 1000 1100 OUTPUT FREQUENCY vs. FREE-AIR TEMPERATURE 1.6 1.2 fO -- Output Frequency -- Normalized IDD -- Supply Current -- mA 800 Figure 2 SUPPLY CURRENT vs. FREE-AIR TEMPERATURE 1.4 1.2 1 0.8 -15 10 35 60 TA - Free-Air Temperature - C 85 1.1 1.0 0.9 0.8 0.7 0.6 0.5 -25 0 25 50 TA - Free-Air Temperature - C Figure 3 Copyright E 2007, TAOS Inc. 4 700 - Wavelength - nm Figure 1 0.6 -40 600 75 Figure 4 The LUMENOLOGY r Company r www.taosinc.com r TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 TYPICAL CHARACTERISTICS NORMALIZED OUTPUT VOLTAGE vs. ANGULAR DISPLACEMENT NORMALIZED OUTPUT VOLTAGE vs. ANGULAR DISPLACEMENT 0.8 0.6 0.4 0.2 0 -90 -Q -60 +Q -30 0 30 60 Q - Angular Displacement - 0.8 0.6 0.4 0.2 0 -90 90 Optical Axis VO -- Output Voltage -- Normalized 1 Optical Axis VO -- Output Voltage -- Normalized 1 -Q -60 -30 0 30 60 Q - Angular Displacement - Figure 5 11k 6.0 10k Temperature Coefficient -- ppm/degC fD -- Dark Frequency -- Hz PHOTODIODE RESPONSIVITY TEMPERATURE COEFFICIENT vs. WAVELENGTH OF INCIDENT LIGHT 7.5 4.5 3.0 1.5 0.0 -1.5 -3.0 NOTE A -6.0 -7.5 -25 90 Figure 6 DARK FREQUENCY vs. FREE-AIR TEMPERATURE -4.5 +Q -5 15 35 55 TA - Free-Air Temperature - C 75 9k 8k 7k 6k 5k 4k 3k 2k 1k 0 600 650 700 750 800 850 900 950 1000 - Wavelength of Incident Light - nm Figure 7 Figure 8 NOTE A: Internal offsets that result in dark frequency can be both positive and negative. The dashed line represents the case of negative offset in which an equivalent amount of light signal is required to obtain a non-zero output frequency. The LUMENOLOGY r Company Copyright E 2007, TAOS Inc. r www.taosinc.com r 5 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 APPLICATION INFORMATION Power-Supply Considerations Power-supply lines must be decoupled by a 0.01-F to 0.1-F capacitor with short leads placed close to the TSL238T (Figure 9). A low-noise power supply is required to minimize jitter on output pulse. VDD VDD 0.1 F TSL238T OUT GND Timer / Port MCU Figure 9. Typical TSL238T Interface to a Microcontroller Device Operational Details The frequency at the output pin (OUT) is given by: fO = fD + (Re) (Ee) where: fO fD Re Ee is the output frequency is the output frequency for dark condition (Ee = 0) is the device responsivity for a given wavelength of light given in kHz/(W/cm2) is the incident irradiance in W/cm2 fD is a constant error term in the output frequency calculation resulting from leakage currents, and is independent of light intensity. The TSL238T die is trimmed to minimize the magnitude of this dark frequency component so that it can be neglected in the transfer function calculation. In many applications, measurement of the actual dark frequency may be impractical due to measurement times ranging from several seconds to several minutes, and the fact that some devices may never transition (zero dark frequency). Output Interface The output of the device is designed to drive a CMOS logic input over short distances. If lines greater than 12 inches in length are used on the output, a buffer or line driver is recommended. Copyright E 2007, TAOS Inc. 6 The LUMENOLOGY r Company r www.taosinc.com r 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 0.90 1.00 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 Copyright E 2007, TAOS Inc. r www.taosinc.com r 7 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 MECHANICAL DATA The TSL238T is supplied in a low-profile surface-mount package. This package contains no lead (Pb). PACKAGE T Four-Lead Surface Mount Device TOP VIEW 1.89 2.60 1.0 3.80 Photodiode (Note C) DETAIL A: TYPICAL PACKAGE TERMINAL 0.10 SIDE VIEW 3.10 0.90 7 0.35 III EEEEEEEE III EEEEEEEE 0.40 0.80 1.35 0.45 R 0.20 0.50 BOTTOM VIEW A 1.50 Pb PIN 1 Lead Free 0.55 NOTES: A. All linear dimensions are in millimeters. B. Terminal finish is gold, 1.3 m minimum. C. The center of the 0.84 mm x 0.84 mm integrated photodiode active area is referenced to the upper left corner of the package (near Pin 1). D. Dimension tolerance is 0.15 mm. E. This drawing is subject to change without notice. Figure 11. Package T -- Four-Lead Surface Mount Device Packaging Configuration Copyright E 2007, TAOS Inc. 8 The LUMENOLOGY r Company r www.taosinc.com r TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 MECHANICAL DATA 2.10 0.30 0.050 SIDE VIEW 1.75 0.100 B 1.50 4 0.100 8 Typ END VIEW 2 0.100 TOP VIEW 12 0.100 5.50 0.100 1.50 R 0.20 TYP B A A DETAIL B DETAIL A 2.90 0.100 Ao 3.09 MAX R 0.20 TYP R 0.20 TYP 4.29 MAX 4.10 0.100 Bo 1.80 Ko NOTES: A. B. C. D. E. F. G. All linear dimensions are in millimeters. The dimensions on this drawing are for illustrative purposes only. Dimensions of an actual carrier may vary slightly. Symbols on drawing Ao, Bo, and Ko are defined in ANSI EIA Standard 481-B 2001. Each reel is 178 millimeters in diameter and contains 1000 parts. TAOS packaging tape and reel conform to the requirements of EIA Standard 481-B. In accordance with EIA standard, device pin 1 is located next to the sprocket holes in the tape. This drawing is subject to change without notice. Figure 12. Four Lead Surface Mount Package Carrier Tape The LUMENOLOGY r Company Copyright E 2007, TAOS Inc. r www.taosinc.com r 9 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 MANUFACTURING INFORMATION The reflow profile specified here describes expected maximum heat exposure of devices during the solder reflow process of the device on a PWB. Temperature is measured at the top of the device. Devices should be limited to one pass through the solder reflow profile. Table 1. TSL238T Solder Reflow Profile PARAMETER REFERENCE TSL238T Average temperature gradient in preheating Soak time 2.5C/sec tsoak 2 to 3 minutes Time above T1, 217C t1 Max 60 sec Time above T2, 230C t2 Max 50 sec Time above T3, (Tpeak -10C) t3 Max 10 sec Tpeak 260 C (-0C/+5C) Peak temperature in reflow Temperature gradient in cooling Tpeak Max -5C/sec Not to scale -- for reference only T3 T2 Temperature (C) T1 Time (sec) t3 t2 tsoak t1 Figure 13. TSL238T Solder Reflow Profile Copyright E 2007, TAOS Inc. 10 The LUMENOLOGY r Company r www.taosinc.com r TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 MANUFACTURING INFORMATION Moisture Sensitivity Optical characteristics of the device can be adversely affected during the soldering process by the release and vaporization of moisture that has been previously absorbed into the package molding compound. To ensure the package molding compound contains the smallest amount of absorbed moisture possible, each device is dry-baked prior to being packed for shipping. Devices are packed in a sealed aluminized envelope with silica gel to protect them from ambient moisture during shipping, handling, and storage before use. This package has been assigned a moisture sensitivity level of MSL 3 and the devices should be stored under the following conditions: Temperature Range Relative Humidity Total Time Opened Time 5C to 50C 60% maximum 6 months from the date code on the aluminized envelope -- if unopened 168 hours or fewer Rebaking will be required if the devices have been stored unopened for more than 6 months or if the aluminized envelope has been open for more than 168 hours. If rebaking is required, it should be done at 90C for 4 hours. The LUMENOLOGY r Company Copyright E 2007, TAOS Inc. r www.taosinc.com r 11 TSL238T HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS080G - DECEMBER 2007 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. Copyright E 2007, TAOS Inc. 12 The LUMENOLOGY r Company r www.taosinc.com r