TCS230中文资料

D High-Resolution Conversion of Light Intensity to FrequencyD Programmable Color and Full-Scale Output Frequency

D Communicates Directly With a Microcontroller D Single-Supply Operation (2.7 V to 5.5 V)D Power Down FeatureD Nonlinearity Error Typically 0.2% at 50 kHz D Stable 200 ppm/°C Temperature Coefficient DLow-Profile Surface-Mount PackageDescription

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) withfrequency directly proportional to light intensity (irradiance). The full-scale output frequency can be scaled by one of threepreset values via two control input pins. Digital inputs and digital output allow direct interface to a microcontroller or otherlogic circuitry. Output enable (OE) places the output in the high-impedance state for multiple-unit sharing of a microcontrollerinput line.

The light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have blue filters, 16photodiodeshave green filters, 16 photodiodes have red filters, and 16 photodiodes are clear with no filters.The four types (colors) ofphotodiodes are interdigitated to minimize the effect of non-uniformity of incident irradiance. All 16 photodiodes of the samecolor are connected in parallel and which type of photodiode the device uses during operation is pin-selectable. Photodiodesare 120 µm x 120 µm in size and are on 144-µm centers.8 S37 S26 OUT 5 V DDSOIC PACKAGE (TOP VIEW)SO 1S1 2OE 3GND 4

Terminal Functions

Table 1. Selectable Options

Available Options

Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)?

Supply voltage, V DD (see Note 1) 6 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Input voltagerange, all inputs, V I –0.3 V to V DD + 0.3 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Operating free-airtemperature range, T A 0°C to 70°

C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Storage temperature range –25°C to 85°C . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ?

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These arestress 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 periodsmay affect device reliability.

NOTE 1:All voltage values are with respect to GND.

Recommended Operating Conditions

Electrical Characteristics at T

= 25°C, V = 5 V (unless otherwise noted)

Operating Characteristics at V DD = 5 V, T A = 25°C, S0 = H, S1 = H (unless otherwise noted) (See Notes 3, 4, 5, 6, and 7).

4.The 470 nm input irradiance is supplied by an I nGaN light-emitting diode with the following characteristics:peak wavelength λp = 470 nm, spectral halfwidth ?λ? = 35 nm, and luminous efficacy = 75 lm/W.

5.The 524 nm input irradiance is supplied by an I nGaN light-emitting diode with the following characteristics:peak wavelength λp = 524 nm, spectral halfwidth ?λ? = 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 ?λ? = 28 nm, and luminous efficacy = 595 lm/W.

7.The 635 nm input irradiance is supplied by a Al I nGaP light-emitting diode with the following characteristics:peak wavelength λp = 635 nm, spectral halfwidth ?λ? = 17 nm, and luminous efficacy = 150 lm/W.8.Irradiance responsivity R e 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 valuesstated in notes

4, 5, and 6 and using 1 lx = 1 lm/m2.

11.Nonlinearity is defined as the deviation of f O from a straight line between zero and full scale, expressed as a percent offull scale.

TYPICAL CHARACTERISTICS

Figure 1300500700900

R e l a t i v e R e s p o n s i v i t y1100λ – Wavelength – nm

PHOTODIODE SPECTRAL RESPONSIVITY0.10.20.30.40.50.60.70.80.910Figure 23005007009001100

λ – Wavelength – nm

PHOTODIODE SPECTRAL RESPONSIVITY WITH

APPLICATION INFORMATIONPower 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 devicepackage.Input interface

A low-impedance electrical connection between the device OE pin and the device GND pin is required forimproved 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 than12 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 Table1).

Output frequency scaling

Output-frequency scaling is controlled by two logic inputs, S0 and S1. The internal light-to-frequency converter generates afixed-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, thefinal-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 newvalid period. This minimizes the time delay between a change on the input lines and the resulting new output period. Theresponse 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 whereperiod measurement techniques are used.Measuring the frequency

The choice of interface and measurement technique depends on the desired resolution and data acquisition rate. Formaximum 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 clockrate. Output scaling can be used to increase the resolution for a given clock rate or to maximize resolution as the light inputchanges. Period measurement is used to measure rapidly varying light levels or to make a very fast measurement of aconstant light source.

Maximum resolution and accuracy may be obtained using frequency-measurement, pulse-accumulation, or integrationtechniques. 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 averagelight levels over short periods of time. Integration (the accumulation of pulses over a very long period of time) can be used tomeasure exposure, the amount of light present in an area over a given time period.

MECHANICAL INFORMATIONPACKAGE D

PLASTIC SMALL-OUTLINE PACKAGE

DETAIL AA

2y 6y 1.8 +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 productMUST allow

for the data sheet tolerances.

D.Pin 4 (GND) is mechanically connected to the die mount pad.E.The 8 × 8 photodiode array area is 1.15 mm × 1.15 mm (1.33 sq. mm).F.This drawing is subject to change without notice.Figure 3. TCS230 Mechanical Specifications

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