TCS230

TCS230 ETC

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COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com High-Resolution Conversion of Light Intensity to Frequency Programmable Color and Full-Scale Output Frequency Communicates Directly With a Microcontroller Single-Supply Operation (2.7 V to 5.5 V) Power Down Feature Nonlinearity Error Typically 0.2% at 50 kHz Stable 200 ppm/°C Temperature Coefficient Low-Profile Surface-Mount Package

Description

The TCS230 programmable color light-to-frequency converter combines configurable silicon photodiodes and a current-to-frequency converter on single monolithic CMOS integrated circuit. The output is a square wave (50% duty cycle) with frequency directly proportional to light intensity (irradiance). The full-scale output frequency can be scaled by one of three preset values via two control input pins. Digital inputs and digital output allow direct interface to a microcontroller or other logic circuitry. Output enable (OE ) places the output in the high-impedance state for multiple-unit sharing of a microcontroller input line. The light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters. The four types (colors) of photodiodes are interdigitated to minimize the effect of non-uniformity of incident irradiance. All 16 photodiodes of the same color are connected in parallel and which type of photodiode the device uses during operation is pin-selectable. Photodiodes are 120 µm x 120 µm in size and are on 144-µm centers. Functional Block Diagram Light Current-to-Frequency ConverterPhotodiode Array S2 S3 S0 S1 OE Output Texas Advanced Optoelectronic Solutions Inc.

800 Jupiter Road, Suite 205 Plano, TX 75074 (972) 673-0759

6 OUT

5 VDD

(TOP VIEW) SO 1 S1 2 OE 3 GND 4

GND 4 Power supply ground. All voltages are referenced to GND. OE 3 I Enable for fo (active low). OUT 6 O Output frequency (fo). S0, S1 1, 2 I Output frequency scaling selection inputs. S2, S3 7, 8 I Photodiode type selection inputs. Table 1. Selectable Options implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. NOTE 1: All voltage values are with respect to GND.

COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com Electrical Characteristics at TA = 25°C, VDD = 5 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT VOH High-level output voltage IOH = –4 mA 4 4.5 V VOL Low-level output voltage IOL = 4 mA 0.25 0.40 V IIH High-level input current 5 µA IIL Low-level input current 5 µA I Supply current Power-on mode 2 3 mA IDD Supply current Power-down mode 7 15 µA S0 = H, S1 = H 500 600 kHz Full-scale frequency (See Note 2) S0 = H, S1 = L 100 120 kHzFull scale frequency (See Note 2) S0 = L, S1 = H 10 12 kHz Temperature coefficient of output frequency λ ≤ 700 nm, –25°C ≤ TA ≤ 70°C ±200 ppm/°C kSVS Supply voltage sensitivity VDD = 5 V ±10% ±0.5 %/V NOTE 2: Full-scale frequency is the maximum operating frequency of the device without saturation.

COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 Copyright 2003, TAOS Inc. The LUMENOLOGY Company www.taosinc.com Operating Characteristics at VDD = 5 V, TA = 25°C, S0 = H, S1 = H (unless otherwise noted) (See Notes 3, 4, 5, 6, and 7). PARAMETER TEST CONDITIONS CLEAR PHOTODIODE S2 = H, S3 = L BLUE PHOTODIODE S2 = L, S3 = H GREEN PHOTODIODE S2 = H, S3 = H RED PHOTODIODE S2 = L, S3 = L UNITCONDITIONS MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX Ee = 45.6 µW/cm 2, λp = 470 nm 16 20 24 11.2 16.4 21.6 kHz fO Output frequency Ee = 39.2 µW/cm 2, λp = 524 nm 16 20 24 8 13.6 19.2 kHz fO frequency Ee = 32.8 µW/cm 2, λp = 635 nm 16 20 24 14 19 24 kHz Ee = 0 2 12 2 12 2 12 2 12 Hz λp = 470 nm 439 360 88 31 R Irradiance responsivity λp = 524 nm 510 189 347 46 Hz/ ( W/R e responsivity (Note 8) λp = 565 nm 548 49 318 110 (µW/ cm 2)(Note 8) λp = 635 nm 610 30 37 579 cm 2) λp = 470 nm 1370 1670 Saturation Irradiance λp = 524 nm 1180 1730 µW/Irradiance (Note 9) λp = 565 nm 1090 1890 µW/ cm 2 (Note 9) λp = 635 nm 980 1040 λp = 470 nm 585 480 117 41 R Illuminance responsivity λp = 524 nm 98 36 67 9 Hz/R v responsivity (Note 10) λp = 565 nm 92 8 53 18 Hz/ lx(Note 10) λp = 635 nm 407 20 25 386 Nonlinearity Recovery from power down 100 100 100 100 µs Response time to out- put enable (OE) 100 100 100 100 ns NOTES: 3. Optical measurements are made using small-angle incident radiation from a light-emitting diode (LED) optical source. 4. The 470 nm input irradiance is supplied by an InGaN light-emitting diode with the following characteristics: peak wavelength λp = 470 nm, spectral halfwidth Δλ ‰ = 35 nm, and luminous efficacy = 75 lm/W. 5. The 524 nm input irradiance is supplied by an InGaN light-emitting diode with the following characteristics: peak wavelength λp = 524 nm, spectral halfwidth Δλ ‰ = 47 nm, and luminous efficacy = 520 lm/W. 6. The 565 nm input irradiance is supplied by a GaP light-emitting diode with the following characteristics: peak wavelength λp = 565 nm, spectral halfwidth Δλ ‰ = 28 nm, and luminous efficacy = 595 lm/W. 7. The 635 nm input irradiance is supplied by a AlInGaP light-emitting diode with the following characteristics: peak wavelength λp = 635 nm, spectral halfwidth Δλ ‰ = 17 nm, and luminous efficacy = 150 lm/W. 8. Irradiance responsivity Re is characterized over the range from zero to 5 kHz. 9. Saturation irradiance = (full-scale frequency)/(irradiance responsivity). 10. Illuminance responsivity Rv is calculated from the irradiance responsivity by using the LED luminous efficacy values stated in notes 4, 5, and 6 and using 1 lx = 1 lm/m2. 11. Nonlinearity is defined as the deviation of fO from a straight line between zero and full scale, expressed as a percent of full scale.

COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 The LUMENOLOGY Company Copyright 2003, TAOS Inc. www.taosinc.com TYPICAL CHARACTERISTICS Figure 1 300 500 700 900 Relative Responsivity 1100 λ – Wavelength – nm TA = 25°C PHOTODIODE SPECTRAL RESPONSIVITY 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0 Green

@ 680 nm Red Clear Green Blue Figure 2 300 500 700 900 Relative Responsivity 1100 λ – Wavelength – nm TA = 25°C PHOTODIODE SPECTRAL RESPONSIVITY WITH EXTERNAL HOYA CM500 FILTER 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Normalized to Clear @ 530 nmClear Green Red Blue

COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 Copyright 2003, TAOS Inc. The LUMENOLOGY Company www.taosinc.com

APPLICATION INFORMATION

Power supply considerations Power-supply lines must be decoupled by a 0.01-µF to 0.1-µF capacitor with short leads mounted close to the device package. 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. Photodiode type (color) selection The type of photodiode (blue, green, red, or clear) used by the device is controlled by two logic inputs, S2 and S3 (see Table 1). Output frequency scaling Output-frequency scaling is controlled by two logic inputs, S0 and S1. The internal light-to-frequency converter generates a fixed-pulsewidth pulse train. Scaling is accomplished by internally connecting the pulse-train output of the converter to a series of frequency dividers. Divided outputs are 50%-duty cycle square waves with relative frequency values of 100%, 20%, and 2%. Because division of the output frequency is accomplished by counting pulses of the principal internal frequency, the final-output period represents an average of the multiple periods of the principle 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, and 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. The response time to an input programming change or to an irradiance step change is one period of new frequency plus 1 µS. The scaled output changes 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 scaled-down outputs may be used where only a slower frequency counter is available, such as low-cost microcontroller, or where period measurement techniques are used. 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. 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. 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.

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. for the data sheet tolerances. D. Pin 4 (GND) is mechanically connected to the die mount pad. F. This drawing is subject to change without notice. Figure 3. TCS230 Mechanical Specifications

COLOR LIGHTTOFREQUENCY CONVERTER TAOS046 – JANUARY 2003 Copyright 2003, TAOS Inc. The LUMENOLOGY Company www.taosinc.com 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 is a registered trademark, and TAOS, the TAOS logo, and Texas Advanced Optoelectronic Solutions are trademarks of Texas Advanced Optoelectronic Solutions Incorporated.