TSL238

r r TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 D High-Resolution Conversion of Light D D D D D D D Intensity to Frequency With No External Components High Irradiance Responsivity . . . 2.3 kHz/(mW/cm2) at λp = 524 nm Low Dark Frequency . . . < 2 Hz at 255 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 PACKAGE D 8-LEAD SOIC (TOP VIEW) NC 1 NC 2 NC 3 NC 4 8 OUT 7 VDD 6 GND 5 OE Description The TSL238 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 TSL238 is characterized for operation over the temperature range of − 25°C to 70°C and is supplied in an 8-lead plastic small outline package. When supplied in the lead (Pb) free package, the device is RoHS compliant. For automotive and other extended temperature applications, please contact TAOS for information. Functional Block Diagram Current-to-Frequency Converter Light Photodiode Output Available Options DEVICE TSL238 TA − 25°C to 70°C PACKAGE − LEADS 8-lead Plastic Small Outline IC PACKAGE DESIGNATOR D ORDERING NUMBER TSL238D The LUMENOLOGY r Company Texas Advanced Optoelectronic Solutions Inc. 1001 Klein Road S Suite 300 S Plano, TX 75074 S (972) 673-0759 r www.taosinc.com 1 r Copyright E 2007, TAOS Inc. TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 Terminal Functions TERMINAL NAME GND NC NC D PKG NO. 6 1, 2, 3 4 TYPE DESCRIPTION Power supply ground. All voltages are referenced to GND. No connection. Substrate. Pin 4 is resistively connected to the substrate of the die, which is at the same potential as pin 6. Pin 4 must either be connected to pin 6 or left unconnected. Pin 4 cannot be used for a ground connection by itself. I O Enable for fO (active low). Output frequency. Supply voltage. OE OUT VDD 5 8 7 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . − 25°C to 70°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . − 40°C to 85°C Solder conditions in accordance with JEDEC J−STD−020A, maximum temperature (see Note 2) . . . 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. NOTES: 1. All voltage values are with respect to GND. 2. The device may be hand soldered provided that heat is applied only to the solder pad and no contact is made between the tip of the solder iron and the device lead. The maximum time heat should be applied to the device is 5 seconds. Recommended Operating Conditions MIN Supply voltage, VDD High-level input voltage, VIH Low-level input voltage, VIL Operating free-air temperature range, TA 2.7 0.8 × VDD 0 − 25 NOM 5 MAX 5.5 VDD 0.5 70 UNIT V V V °C Electrical Characteristics at VDD = 5 V, TA = 25°C (Note 1) (unless otherwise noted) PARAMETER VOH VOL IIH IIH IDD High-level output voltage Low-level output voltage High-level input current Low-level input current Supply current Full-scale frequency (Note 2) Temperature coefficient of output frequency kSVS Supply-voltage sensitivity Ee = 21.2 μW/cm2 TA = 50°C (Note 3) Wavelength < 700nm, fO = 50 kHz VDD = 5 V ±10% 500 ± 200 ± 0.5 TEST CONDITIONS IOH = − 1 mA IOL = 1 mA −10 −10 2 MIN 4 TYP 4.5 0.25 0.4 10 10 3 1000 MAX UNIT V V μA μA mA kHz ppm/°C %/ V NOTES: 1. The input irradiance is supplied with green LED light source with peak wavelength = 524 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 μW/sqcm 524-nm irradiance. During production testing, devices are not tested at this very high irradiance level. 3. Measured at wafer probe using 50°C hot chuck. Copyright E 2007, TAOS Inc. r r The LUMENOLOGY r Company 2 www.taosinc.com TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 Operating Characteristics at VDD = 5 V, TA = 25°C, λp = 524 nm (unless otherwise noted) PARAMETER fO fD Re λp Output frequency Dark frequency Irradiance responsivity Peak response wavelength Nonlinearity (Note 2) Step response to full-scale step input fO = 0 kHz to 10 kHz Ee = 0 TEST CONDITIONS Ee = 21.2 μW/cm2 μW/cm2 Ee = 0 μW/cm2, TA = 50°C (Note 1) MIN 40 0 0 2.3 700 ± 1% 1 pulse of new frequency plus 1 μs TYP 50 MAX 60 1.2 6 UNIT kHz Hz Hz kHz/(μW/ cm2) nm %F.S. NOTES: 1. Measured at wafer probe using 50°C 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 r r Copyright E 2007, TAOS Inc. www.taosinc.com 3 TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 TYPICAL CHARACTERISTICS OUTPUT FREQUENCY vs IRRADIANCE 1000 VDD = 5 V λp = 524 nm TA = 25°C Normalized Responsivity 1 PHOTODIODE SPECTRAL RESPONSIVITY Output Frequency (fO − fD) — kHz 100 0.8 10 0.6 1 0.4 0.1 0.01 0.2 0.001 0.001 0.01 0.1 1 10 μW/cm2 10 0 1k 0 300 400 500 600 700 800 900 1000 1100 Ee − Irradiance − λ − Wavelength − nm Figure 1 SUPPLY CURRENT vs. FREE-AIR TEMPERATURE 2.0 1.200 fO — Output Frequency — Normalized 1.100 1.000 0.900 0.800 0.700 0.600 0.500 −25 Figure 2 OUTPUT FREQUENCY vs. FREE-AIR TEMPERATURE IDD — Supply Current — mA 1.6 1.2 0.8 0.4 0 −25 0 25 50 TA − Free-Air Temperature − °C 75 0 25 50 TA − Free-Air Temperature − °C 75 Figure 3 Figure 4 Copyright E 2007, TAOS Inc. r r The LUMENOLOGY r Company 4 www.taosinc.com TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 TYPICAL CHARACTERISTICS NORMALIZED OUTPUT FREQUENCY vs. ANGULAR DISPLACEMENT 1 fO — Output Frequency — Normalized 0.8 Optical Axis Angular Displacement is Equal for Both Aspects 0 −90 −60 −30 0 30 60 Q − Angular Displacement − ° 90 0.6 0.4 0.2 Figure 5 DARK FREQUENCY vs. FREE-AIR TEMPERATURE 7.5 6.0 fD — Dark Frequency — Hz 4.5 3.0 1.5 0.0 −1.5 −3.0 −4.5 −6.0 −7.5 −25 −5 15 35 55 TA − Free-Air Temperature − °C 75 NOTE A Figure 6 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 r r Copyright E 2007, TAOS Inc. www.taosinc.com 5 TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 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 TSL238 (Figure 7). A low-noise power supply is required to minimize jitter on output pulse. VDD VDD 0.1 μF TSL238 OUT Timer / Port GND MCU Figure 7. Typical TSL238 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/(μW/cm2) is the incident irradiance in μW/cm2 fD is a constant error term in the output frequency calculation resulting from leakage currents, and is independent of light intensity. The TSL238 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. r r The LUMENOLOGY r Company 6 www.taosinc.com TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 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. The LUMENOLOGY r Company r r Copyright E 2007, TAOS Inc. www.taosinc.com 7 TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 MECHANICAL DATA This SOIC package consists of an integrated circuit mounted on a lead frame and encapsulated with an electrically nonconductive clear plastic compound having an index of refraction of 1.55. PACKAGE D TOP VIEW PLASTIC SMALL-OUTLINE BOTTOM VIEW PIN 1 NOTE B PIN 1 6 y 1.27 8 y 0.510 0.330 SIDE VIEW j 2.8 TYP CLEAR WINDOW END VIEW 0.50 0.25 455 0.88 TYP TOP OF SENSOR DIE A 1.75 1.35 4.00 3.80 6.20 5.80 0.25 0.19 5.00 4.80 5.3 MAX DETAIL A Pb 1.27 0.41 0.25 0.10 NOTES: A. All linear dimensions are in millimeters. B. The center of the 0.84-mm by 0.84-mm photo-active area is located in the center of the package ± 0.25 mm. C. Pin 4 is resistively coupled to the substrate of the die, which is at the same potential as Pin 6. Pin 4 must either be connected to Pin 6 or left unconnected. Pin 4 cannot be used as the sole ground connection. D. Leads are plated with Pd (min 0.1 μ inch) + Ni (min 10 μ inch) + Au (min 0.1 μ inch). E. This drawing is subject to change without notice. Figure 8. Package D — Plastic Small Outline IC Packaging Configuration Copyright E 2007, TAOS Inc. r r The LUMENOLOGY r Company 8 www.taosinc.com TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 MECHANICAL DATA SIDE VIEW Ko 2.11 + 0.10 [0.083 + 0.004] 0.292 + 0.013 [0.0115 + 0.0005] TOP VIEW j 1.50 8 + 0.1 [0.315 + 0.004] 4 + 0.1 [0.157 + 0.004] 2 + 0.05 [0.079 + 0.002] 1.75 + 0.10 [0.069 + 0.004] END VIEW B 5.50 + 0.05 [0.217 + 0.002] 12 + 0.3 − 0.1 [0.472 + 0.12 − 0.004] A A B DETAIL A DETAIL B Ao NOTES: A. B. C. D. E. F. 6.45 + 0.10 [0.254 + 0.004] Bo 5.13 + 0.10 [0.202 + 0.004] All linear dimensions are in millimeters [inches]. 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. This drawing is subject to change without notice. Figure 9. Package D Carrier Tape The LUMENOLOGY r Company r r Copyright E 2007, TAOS Inc. www.taosinc.com 9 TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 MANUFACTURING INFORMATION The Plastic Small Outline IC package (D) has been tested and has demonstrated an ability to be reflow soldered to a PCB substrate. The solder reflow profile describes the expected maximum heat exposure of components during the solder reflow process of product on a PCB. Temperature is measured on top of component. The component should be limited to a maximum of three passes through this solder reflow profile. Table 1. TSL238 Solder Reflow Profile PARAMETER Average temperature gradient in preheating Soak time Time above 217°C Time above 230°C Time above Tpeak −10°C Peak temperature in reflow Temperature gradient in cooling tsoak t1 t2 t3 Tpeak REFERENCE TSL238 2.5°C/sec 2 to 3 minutes Max 60 sec Max 50 sec Max 10 sec 260° C (−0°C/+5°C) Max −5°C/sec Tpeak Not to scale — for reference only T3 T2 T1 Temperature (5C) Time (sec) tsoak Figure 10. Solder Reflow Profile Graph t3 t2 t1 Copyright E 2007, TAOS Inc. r r The LUMENOLOGY r Company 10 www.taosinc.com TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 2007 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 prevent these adverse conditions, all devices shipped in carrier tape have been pre-baked and shipped in a sealed moisture-barrier bag. No further action is necessary if these devices are processed through solder reflow within 24 hours of the seal being broken on the moisture-barrier bag. However, for all devices shipped in tubes or if the seal on the moisture barrier bag has been broken for 24 hours or longer, it is recommended that the following procedures be used to ensure the package molding compound contains the smallest amount of absorbed moisture possible. For devices shipped in tubes: 1. Remove devices from tubes 2. Bake devices for 4 hours, at 90°C 3. After cooling, load devices back into tubes 4. Perform solder reflow within 24 hours after bake Bake only a quantity of devices that can be processed through solder reflow in 24 hours. Devices can be re-baked for 4 hours, at 90°C for a cumulative total of 12 hours (3 bakes for 4 hours at 90°C). For devices shipped in carrier tape: 1. Bake devices for 4 hours, at 90°C in the tape 2. Perform solder reflow within 24 hours after bake Bake only a quantity of devices that can be processed through solder reflow in 24 hours. Devices can be re−baked for 4 hours in tape, at 90°C for a cumulative total of 12 hours (3 bakes for 4 hours at 90°C). The LUMENOLOGY r Company r r Copyright E 2007, TAOS Inc. www.taosinc.com 11 TSL238 HIGH-SENSITIVITY LIGHT-TO-FREQUENCY CONVERTER TAOS073F − OCTOBER 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. r r The LUMENOLOGY r Company 12 www.taosinc.com