SDP8476-201 Low Light Rejection Phototransistor FEATURES • Side-looking plastic package • Low light level immunity • 50¡ (nominal) acceptance angle • Mechanically and spectrally matched to SEP8506 and SEP8706 infrared emitting diodes INFRA-21.TIF DESCRIPTION The SDP8476 is an NPN silicon phototransistor which internal base- emitter shunt resistance. Transfer molding of this device in a clear T- 1 plastic package assures superior optical centerline performance compared to other molding processes. Lead lengths are staggered to provide a simple method of polarity identification. OUTLINE DIMENSIONS in inches (mm) Tolerance 3 plc decimals ±0.005(0.12) 2 plc decimals ±0.020(0.51) Distinguising Feature: This device incorporates all of the desired features of a standard phototransistor with the advantage of low light immunity. The phototransistor switching occurs when the incident light increases above the threshold (knee point). When the light level exceeds the knee point of the device, it will function as a standard phototransistor. Chart A illustrates the light current output of the low light rejection phototransistor as compared to a standard phototransistor with similar sensitivity. Typical Application Uses: Ideally suited for use in applications which require ambient light rejection, or in transmissive applications where the interrupter media is semi- transparent to infrared energy. This device also provides high contrast ratio in reflective applications where unwanted background reflection is a possibility. DIM_017.ds4 142 h Honeywell reserves the right to make changes in order to improve design and supply the best products possible. SDP8476-201 Low Light Rejection Phototransistor ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL MIN TYP MAX ABSOLUTE MAXIMUM RATINGS UNITS TEST CONDITIONS SCHEMATIC (25¡C Free-Air Temperature unless otherwise noted) Collector-Emitter Voltage Power Dissipation Operating Temperature Range Storage Temperature Range Soldering Temperature (5 sec) 30 V 100 mW [À] -40¡C to 85¡C -40¡C to 85¡C 240¡C Notes 1. Derate linearly from 25¡C free-air temperature at the rate of 0.78 mW/¡C. Honeywell reserves the right to make changes in order to improve design and supply the best products possible. h 143 SDP8476-201 Low Light Rejection Phototransistor SWITCHING TIME TEST CIRCUIT SWITCHING WAVEFORM cir_015.cdr Fig. 1 Responsivity vs Angular Displacement Fig. 2 gra_036.ds4 Relative response -60 -45 -30 -15 Spectral Responsivity gra_054.ds4 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Relative response cir_004.cdr 0 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 +15 +30 +45 +60 400 600 Angular displacement - degrees Fig. 3 Fig. 4 Dark Current vs Temperature gra_310.ds4 Normalized collector current Dark Current - nA Collector Current vs Ambient Temperature gra_039.ds4 2.0 1000 100 800 1000 1200 Wavelength - nm Vce = 15 H=0 10 1 0.1 0.01 -55 -35 -15 5 25 45 65 85 105 125 1.6 1.2 0.8 0.4 0.0 Free-air temprerature - °C 0 10 20 30 40 50 60 70 80 Ambient temperature - °C All Performance Curves Show Typical Values 144 h Honeywell reserves the right to make changes in order to improve design and supply the best products possible. SDP8476-201 Low Light Rejection Phototransistor Chart A. Low Light Rejection Phototransistor vs. Standard Phototransistor Light current - mA 6.00 5.00 Min. Light Current Slope 4.00 Max. Light Current Slope 3.00 Min. Light Current Slope Standard Max. Light Current Slope Standard 2.00 1.00 0.00 0.00 0.25 0.50 0.75 1.00 2 Source intensity - mW/cm Designing with the Low Light Rejection Phototransistor: The Low Light Rejection detector is tested at different incident light levels to determine adherence to the specified knee point and light current slope. This method assures proper functionality vs. standard phototransistors, and guarantees required light current output. The knee point, the source irradiance needed to increase IL to 50uA, is a necessary parameter for circuit design. All variation in the knee point will be offset by the internally guardbanded light current slope limits. The appropriate formula for circuit design is the following: The light current slope is the change in light current output at two given source irradiances divided by the change in the two source irradiances. Where: • IL is the light current output in mA • IL slopeMIN. is the minimum limit on the light current 2 slope (i.e. 1.0mA/mW/cm ) • HA is the source light incident on the detector for the application • HKP is the specified level of source light incident on the detector at the typical knee point (i.e. 0.125 2 mW/cm ) (Formula # 1) IL Slope = [IL 1 (@ H1 ) - IL2 (@ H2 )] / [H1 - H2] Where: 2 • IL slope is the light current slope in mA/mW/cm • IL is the light current output in mA 2 • H is the source intensity in mW/cm Chart A shows the specified limits of light current slope for the low light rejection phototransistor which begins its 2 slope at the typical knee point, 0.25mW/cm . To make a clear distinction between this device and a standard phototransistor, light current slopes for high and low sensitivity standard phototransistors are also shown. Note that for phototransistors of the same gain, the slopes of the two products are parallel. Honeywell reserves the right to make changes in order to improve design and supply the best products possible. (Formula # 2) IL = IL slopeMIN. * (HA - HKP) To design a transmissive sensor with two of Honeywell’s standard components, the SEP8506-003 and the SDP8476-201, it is first necessary to determine the 2 irradiance level in mW/cm that will be incident on the detector. The application conditions are the following: 145 SDP8476-201 Low Light Rejection Phototransistor Supply voltage = 5V Distance between emitter and detector = 0.535 in. (13.6mm) IRED drive current = 20mA 2 The SEP8506-003 gives 0.45mW/cm min. to 2 0.90mW/cm max. under the above conditions. To obtain minimum light current output, use the minimum irradiance limit. Light current output = IL slopeMIN. * (HA - HKP) 2 Light current output = 1.0 mA/mW/cm min. * 2 2 (0.45mW/cm min. - 0.25 mW/cm ) = 0.2mA min. 146 Honeywell reserves the right to make changes in order to improve design and supply the best products possible.