ISL29000 Ver la hoja de datos (PDF) - Renesas Electronics
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ISL29000 Datasheet PDF : 7 Pages
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ISL29000
TABLE 1. VDD = 5V, MAXIMUM OUTPUT VOLTAGE = 4.7V
ILLUMINATION RANGE
(LUX)
RLOAD
(k)
CURRENT OUT
(µA)
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
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:
R1
=
R2
0--3--.--.2-0--5--V--V--
–
1
=
11 R2
(EQ. 4)
3V TO 5V
SUPPLY VOLTAGE
3V DC VOLTAGE
VDO
ISL29000
EN
OUT
GND
R2
110k
TO INVERTER BRIGHTNESS
INPUT OR LED DRIVER
CONTROLLER
R1
10k
C1
25µF
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:
R2
=
1--1--2-.--25---5----V-A--
=
10 k
(EQ. 5)
and
R1 = 11 R2 = 110k
(EQ. 6)
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.
3V TO 5V
SUPPLY VOLTAGE
3V PWM CONTROL
VDO
ISL29000
EN
OUT
GND
R2
110k
TO INVERTER BRIGHTNESS
INPUT OR LED DRIVER
CONTROLLER
R1
10k
C1
25µF
FIGURE 10. AUTOMATIC DIMMING SOLUTION WITH
ADJUSTABLE BIAS CONTROL
Figure 11 shows how a fully manual override can be quickly
added by using the EN pin.
3V TO 5V
SUPPLY VOLTAGE
3V PWM CONTROL
VDO
ENABLE/
DISABLE
CONTROL
ISL29000
EN
OUT
GND
R2
110k TO INVERTER
BRIGHTNESS
INPUT OR LED
DRIVER
CONTROLLER
R1
10k
C1
25µF
FIGURE 9. AUTOMATIC DIMMING SOLUTION
Next, the value of R2 can be calculated based on the
maximum output current coming from the ISL29000 under the
FN6117 Rev 6.00
September 2, 2008
FIGURE 11. AUTOMATIC DIMMING SOLUTION WITH
ADJUSTABLE BIAS CONTROL AND MANUAL
OVERRIDE
Page 5 of 7
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