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ISL29000IROZ-T7 Datasheet(PDF) 5 Page - Intersil Corporation |
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ISL29000IROZ-T7 Datasheet(HTML) 5 Page - Intersil Corporation |
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5 / 7 page  5 FN6117.4 February 9, 2007 Application Examples The following examples present from fully automatic to fully manual override implementations. These guidelines are applicable to a wide variety of potential light control applications. The ISL29000 can be used to control the brightness input of CCFL inverters. Likewise it can interface well with LED drivers. In each specific application, it is important to recognize the target environment and its ambient light conditions. The mechanical mounting of the sensor, light aperture hole size and use of a light pipe or bezel are critical in determining the response of the ISL29000 for a given exposure of light. The example in Figure 9 shows a fully automatic dimming solution with no user interaction. Choose R1 and R2 values for any desired minimum brightness and slope. Choose C1 to adjust response time and to filter 50/60Hz room lighting. For example, suppose you wish to generate an output voltage from 0.25V to 1.25V to drive the input of an LED driver controller. The 0.25V represents the minimum LED brightness and 1.25V represents the maximum. The 1st step would be to determine the ratio of R1 and R2: Next, the value of R2 can be calculated based on the maximum output current coming from the ISL29000 under the application's maximum light exposure. Suppose the current has been determined to be about 125µA. Thus, R2 can be calculated approximately using Equations 5 and 6: and In Figure 10, user adjustable bias control has been added to allow control over the minimum and maximum output voltage. This allows the user to adjust the output brightness to personal preference over a limit range via the 3V PWM control. Figure 11 shows how a fully manual override can be quickly added by using the EN pin. TABLE 1. VDD = 5V, MAXIMUM OUTPUT VOLTAGE = 4.7V ILLUMINATION RANGE (LUX) RLOAD (k Ω) CURRENT OUT (µA) 0 to 10 7830 0 to 0.6 0 to 200 392 0 to 12 0 to 500 157 0 to 30 0 to 1,000 80 0 to 60 0 to 10,000 8.00 0 to 600 R 1 R 2 3.0V 0.25V ---------------- 1 – ⎝⎠ ⎛⎞ × 11 R 2 × == (EQ. 4) 3V TO 5V SUPPLY VOLTAGE 3V DC VOLTAGE ISL29000 OUT EN GND VDO C1 R1 R2 FIGURE 9. AUTOMATIC DIMMING SOLUTION 10k 25µF 110k TO INVERTER BRIGHTNESS INPUT OR LED DRIVER CONTROLLER R 2 1.25V 125 μA ------------------ ⎝⎠ ⎛⎞ 10k Ω == (EQ. 5) R 1 11 R 2 × 110k Ω == (EQ. 6) 3V TO 5V SUPPLY VOLTAGE 3V PWM CONTROL ISL29000 OUT EN GND VDO FIGURE 10. AUTOMATIC DIMMING SOLUTION WITH ADJUSTABLE BIAS CONTROL C1 R1 R2 10k 25µF 110k TO INVERTER BRIGHTNESS INPUT OR LED DRIVER CONTROLLER 3V TO 5V SUPPLY VOLTAGE 3V PWM CONTROL ISL29000 OUT EN GND VDO FIGURE 11. AUTOMATIC DIMMING SOLUTION WITH ADJUSTABLE BIAS CONTROL AND MANUAL OVERRIDE ENABLE/ CONTROL DISABLE C1 R1 R2 10k 25µF 110k TO INVERTER BRIGHTNESS INPUT OR LED DRIVER CONTROLLER ISL29000 |
Similar Part No. - ISL29000IROZ-T7 |
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Similar Description - ISL29000IROZ-T7 |
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