TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 High-Resolution Conversion of Light PACKAGE D 8-LEAD SOIC (TOP VIEW) Intensity to Frequency With No External Components Programmable Sensitivity and Full-Scale Output Frequency Communicates Directly With a Microcontroller High Irradiance Responsivity . . . 830 Hz/(W/cm2) Typical at 640 nm Single-Supply Operation . . . 2.7 V to 5.5 V Power-Down Feature . . . 5 A Typical Nonlinearity Error Typically 0.2% at 100 kHz Stable 200 ppm/°C Temperature Coefficient Low-Profile Surface-Mount Package S0 1 8 S3 S1 2 7 S2 OE 3 6 OUT GND 4 5 VDD Description The TSL230RD programmable light-to-frequency converter combines a configurable silicon photodiode and a current-to-frequency converter on single monolithic CMOS integrated circuit. The output can be either a pulse train or a square wave (50% duty cycle) with frequency directly proportional to light intensity. Device sensitivity is selectable in three ranges, providing two decades of adjustment. The full-scale output frequency can be scaled by one of four preset values. All inputs and the output are TTL compatible, allowing direct two-way communication with a microcontroller for programming and output interface. The output enable (OE) places the output in the 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. It is characterized over the temperature range of -25°C to 70°C. Functional Block Diagram Output Light Photodiode Array Current-to-Frequency Converter OE S0 The LUMENOLOGY Company S1 S2 S3 Copyright 2003, TAOS Inc. Texas Advanced Optoelectronic Solutions Inc. 800 Jupiter Road, Suite 205 Plano, TX 75074 (972) 673-0759 www.taosinc.com 1 TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 Terminal Functions TERMINAL TYPE DESCRIPTION NAME NO. GND 4 OE 3 I Enable for fO (active low) OUT 6 O Scaled-frequency (fO) output S0, S1 1, 2 I Sensitivity-select inputs S2, S3 7, 8 I fO scaling-select inputs VDD Ground 5 Supply voltage Selectable Options S1 S0 SENSITIVITY S3 S2 fO SCALING (divide-by) L L Power down L L 1 L H 1× L H 2 H L 10× H L 10 H H 100× H H 100 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage, VDD (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V Input voltage range, all inputs, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 0.3 V to VDD + 0.3 V Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 25°C to 70°C Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - 25°C to 85°C Solder conditions in accordance with JEDEC J-STD-020A, maximum temperature . . . . . . . . . . . . . . . 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 Supply voltage, VDD High-level input voltage, VIH Low-level input voltage, VIL VDD = 4.5 V to 5.5 V VDD = 4.5 V to 5.5 V Operating free-air temperature range, TA Copyright 2003, TAOS Inc. NOM MAX 2.7 5 5.5 UNIT V 2 VDD V 0 0.8 V - 25 70 °C The LUMENOLOGY Company 2 MIN www.taosinc.com TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 Electrical Characteristics at TA = 25°C, VDD = 5 V (unless otherwise noted) PARAMETER TEST CONDITIONS VOH High-level output voltage IOH = -4 mA VOL Low-level output voltage IOL = 4 mA IIH High-level input current IIL Low-level input current MIN TYP 4 MAX 4.5 UNIT V 0.25 0.4 V 5 µA 5 µA Power-on mode 2 3 mA Power-down mode 5 12 µA IDD Supply current F.S. Full-scale frequency (See Note 2) S0=S1=H, S2=S3=L Temperature coefficient of output frequency λ ≤ 700 nm (See Note 3) ±200 ppm/°C Supply voltage sensitivity VDD = 5 V ±10% ±0.5 %/V kSVS 1.1 MHz NOTES: 2. Full-scale frequency is the maximum operating frequency of the device without saturation. 3. The temperature coefficient of output frequency is measured with constant irradiance as the temperature is varied between -25°C and 70°C. The constant irradiance is sufficiently high that the output frequency is much greater than the dark frequency over the entire temperature range. Operating Characteristics at VDD = 5 V, TA = 25°C, Ee = 120 µW/cm2, λp = 640 nm (unless otherwise noted) TSL230RD PARAMETER fO TEST CONDITIONS Output frequency TYP MAX S0 = S1 = H, S2 = S3 = L 80 100 120 kHz S1 = H, S0 = S2 = S3 = L 8 10 12 kHz S0 = H, S1 = S2 = S3 = L 0.8 1 1.2 kHz S0 = S1 = S2 = H, S3 = L 40 50 60 kHz S0 = S1 = S3 = H, S2 = L 8 10 12 kHz 1 1.2 kHz 0.4 10 Hz S0 = S1 = S2 = S3 = H fD Dark frequency Ee = 0, Re Responsivity S0 = S1 = H, S2 = S3 = L tw Output pulse duration 0.8 S0 = S1 = H, S2 = S3 = L kHz/ (µW/cm2) 0.83 S2 = S3 = L 125 S2 or S3 = H Nonlinearity (See Notes 4 and 5) UNIT MIN 600 ns 1/2fO s fO = 0 MHz to 10 kHz ±0.1% %F.S. fO = 0 MHz to 100 kHz ±0.2% %F.S. fO = 0 MHz to 1 MHz ±0.5% Recovery from power down %F.S. 100 µs 1 pulse of new frequency plus 1 µs Step response to full-scale step input 2 periods of new principal frequency plus 1 µs (Note 6) Response time to programming change Response time to output enable (OE) 50 150 ns NOTES: 4. Nonlinearity is defined as the deviation of fO from a straight line between zero and full scale, expressed as a percent of full scale. 5. Nonlinearity test condition: S0 = S1 = H, S2 = S3 = L. 6. Principal frequency is the internal oscillator frequency, equivalent to divide-by-1 output selection. The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com 3 TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 TYPICAL CHARACTERISTICS OUTPUT FREQUENCY vs IRRADIANCE PHOTODIODE SPECTRAL RESPONSIVITY 1.2 VDD = 5 V λp = 640 nm TA = 25°C S2 = S3 = L 100 10 1.0 Normalized Responsivity Output Frequency (fO - fD) — kHz 1000 S0 = H, S1 = H 1 0.1 S0 = L, S1 = H 0.01 0.8 0.6 0.4 0.2 S0 = H, S1 = L 0.001 0.001 0.01 0.1 1 10 100 1k 10k 100k 0 300 1M 400 500 600 DARK FREQUENCY vs TEMPERATURE 1.2 fD — Dark Frequency — Hz VDD = 5 V Ee = 0 S0 = S1 = H S2 = S3 = L 0.8 0.6 0.4 0.2 0 -25 0 25 1000 1100 50 75 7000 VDD = 5 V 6000 5000 4000 3000 2000 1000 0 300 400 500 600 700 800 900 1000 λ - Wavelength of Incident Light - nm Figure 3 Figure 4 The LUMENOLOGY Company 4 900 TEMPERATURE COEFFICIENT OF OUTPUT FREQUENCY vs WAVELENGTH OF INCIDENT LIGHT TA - Temperature - °C Copyright 2003, TAOS Inc. 800 Figure 2 Temperature Coefficient of Output Frequency — ppm/C Figure 1 1 700 λ - Wavelength - nm Ee - Irradiance - µW/cm2 www.taosinc.com TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 TYPICAL CHARACTERISTICS OUTPUT FREQUENCY vs SUPPLY VOLTAGE 1.010 TA = 25°C fO = 100 kHz Normalized Output Frequency 1.005 1.000 0.995 0.990 0.985 0.980 2.5 3 3.5 4 4.5 5 5.5 VDD - Supply Voltage - V Figure 5 The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com 5 TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 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 TSL230RD device package. A low-noise power supply is required to minimize jitter on output pulses. 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 an output frequency resulting from leakage currents. As shown in the equation above, this frequency represents a light-independent term in the total output frequency fO. At very low light levels, this dark frequency can be a significant portion of fO. The dark frequency is temperature dependent. For optimum performance of any given device over the full output range, the value of fD should be measured (in the absence of light) and later subtracted from subsequent light measurement (see Figure 1). Input Interface A low-impedance electrical connection between the device OE pin and the device GND pin is required for improved noise immunity. 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. Sensitivity Adjustment Sensitivity is controlled by two logic inputs, S0 and S1. Sensitivity is adjusted using an electronic iris technique — effectively an aperture control — to change the response of the device to a given amount of light. The sensitivity can be set to one of three levels: 1×, 10× or 100×, providing two decades of adjustment. This allows the responsivity of the device to be optimized to a given light level while preserving the full-scale output-frequency range. Changing of sensitivity also changes the effective photodiode area by the same factor. Copyright 2003, TAOS Inc. The LUMENOLOGY Company 6 www.taosinc.com TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 APPLICATION INFORMATION Output-Frequency Scaling Output-frequency scaling is controlled by two logic inputs, S2 and S3. Scaling is accomplished on chip by internally connecting the pulse-train output of the converter to a series of frequency dividers. Divided outputs available are divide-by 2, 10, 100, and 1 (no division). Divided outputs are 50 percent-duty-cycle square waves while the direct output (divide-by 1) is a fixed-pulse-width pulse train. Because division of the output frequency is accomplished by counting pulses of the principal (divide-by 1) frequency, the final-output period represents an average of n (where n is 2, 10, or 100) periods of the principal frequency. The output-scaling-counter registers are cleared upon the next pulse of the principal frequency after any transition of the S0, S1, S2, S3, or OE lines. The output goes high upon the next subsequent pulse of the principal frequency, beginning a new valid period. This minimizes the time delay between a change on the input lines and the resulting new output period in the divided output modes. In contrast with the sensitivity adjust, use of the divided outputs lowers both the full-scale frequency and the dark frequency by the selected scale factor. The frequency-scaling function allows the output range to be optimized for a variety of measurement techniques. The divide-by-1 or straight-through output can be used with a frequency counter, pulse accumulator, or high-speed timer (period measurement). The divided-down outputs may be used where only a slower frequency counter is available, such as a low-cost microcontroller, or where period measurement techniques are used. The divide-by-10 and divide-by-100 outputs provide lower frequency ranges for high resolution-period measurement. 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. Using the divide-by-2 output, data can be collected at a rate of twice the output frequency or one data point every microsecond for full-scale output. Period measurement requires the use of a fast reference clock with available resolution directly related to reference-clock rate. Output scaling can be used to increase the resolution for a given clock rate or to maximize resolution as the light input changes. Period measurement is used to measure rapidly varying light levels or to make a very 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 or from noise in the power supply. 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 Company Copyright 2003, TAOS Inc. www.taosinc.com 7 TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 APPLICATION INFORMATION PCB Pad Layout Suggested PCB pad layout guidelines for the D package is shown in Figure 6. 3.81 6.60 4.19 1.27 9.01 2.41 0.64 NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. Figure 6. Suggested D Package PCB Layout Copyright 2003, TAOS Inc. The LUMENOLOGY Company 8 www.taosinc.com TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 MECHANICAL INFORMATION This SOIC package consists of an integrated circuit mounted on a lead frame and encapsulated with an electrically nonconductive clear plastic compound. The TSL230RD has a 10 × 10 array of photodiodes with a total size of 0.96 mm by 0.96 mm. The photodiodes are 0.084 mm × 0.084 mm in size and are positioned on 0.096 mm centers. PACKAGE D PLASTIC SMALL-OUTLINE 5.1 0.10 8 7 6 5 (Center of photodiode array coincides CL with package center.) 4.1 0.12 7.3 0.20 A 1 2 3 4 2 0.65 0.10 6 1.27 0.10 DETAIL A 0.8 0.1 1.8 0.200 8 0.175 0.175 0.215 0.035 0.4 Nom 8 0.65 0.12 3.5 + 3.5 - 7 0.825 0.425 NOTES: A. All linear dimensions are in millimeters. B. Package is molded with an electrically nonconductive clear plastic compound having an index of refraction of 1.55. C. Actual product will vary within the mechanical tolerances shown on this specification. Designs for use of this product MUST allow for the data sheet tolerances. D. This drawing is subject to change without notice. Figure 7. Package D — Plastic Small Outline IC Packaging Configuration The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com 9 TSL230RD PROGRAMMABLE LIGHT−TO−FREQUENCY CONVERTERS TAOS054 - SEPTEMBER 2003 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 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 2003, TAOS Inc. The LUMENOLOGY Company 10 www.taosinc.com