ISL29004IROZ Intersil, ISL29004IROZ Datasheet - Page 11

• Manufacturer Part Number: ISL29004IROZ
• Description: IC SENSOR LIGHT-DGTL I2C 8-ODFN
• Manufacturer: Intersil
• Series: -r

Specifications of ISL29004IROZ

• Wavelength: 550nm
• Output Type: I²C™
• Package / Case: 8-WFDFN Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The Full Scale Range, FSR, needs to be determined. From
Equation 3:
FSR
FSR
The effective transfer function becomes:
E
Solution 2 - Using External Timing Mode
From solution 1, the desired integration time is 100ms. Note
that the R
frequency when using external timing mode. Instead the
integration time is the time between two sync_iic commands
sent through the I
many I
commands.
i
i
i
sent 1,000 cycles after another sync_iic command rejects
both 60Hz and 50Hz AC noise signals.
Next is to pick an arbitrary R
Gain/Range Mode. For a maximum 500Lux, Range1 is
adequate. From Equation 3:
FSR
FSR
The effective transfer function becomes:
I2C
I2C
I2C
E
DESIGN PARAMETER
TABLE 14. SOLUTION1 SUMMARY TO EXAMPLE DESIGN
=
DATA is the sensor reading data located in data registers
04(hex) and 05(hex)
COUNTER is the timer counter value data located in data
registers 06(hex) and 07(hex). In this sample problem,
COUNTER = 1000.
=
Gain/Range Mode
Transfer Function
= 1,000 I
= f
= 10kHz
data
------------ -
# of clock cycles
=
=
2
=
=
------------------------------- -
COUNTER
16
2
I2C *
1000lux
1000Lux
2000Lux
1000Lux
C clock cycles to wait between two external timing
DATA
R
×
FSR
EXT
T
EXT
2000Lux
int
T
PROBLEM
2
*
int
100ms
C clock cycles. An external sync_iic command
resistor only determines the inter oscillator
100kΩ
----------------- -
100kΩ
100kΩ
----------------- -
= number of I
50kΩ
×
2
1000Lux
C. The programmer determines how
EXT
11
2
C clock cycles
E
= 100kΩ and to choose the
Range1 = 1000Lux
=
DATA
---------------- -
2
2000Lux
16
VALUE
100ms
50kΩ
2
16
×
2000Lux
ISL29004
Light Source Detection and Infra-Red Rejection
Any filament type light source has a high presence of infrared
component invisible to the human eye. A white fluorescent
lamp, on the other hand has a low IR content. As a result,
output sensitivity may vary depending on the light source.
Maximum attenuation of IR can be achieved by properly
scaling the readings of Diode1 and Diode2. The user obtains
data reading from sensor diode 1, D1, which is sensitive to
visible and IR, then reading from sensor diode 2, D2 which is
mostly sensitive from IR. The graph on Figure 7 shows the
effective spectral response after applying Equation 15 of the
ISL29003 from 400nm to 1000nm. The equation below
describes the method of cancelling IR in internal timing mode.
Where:
D3 = Lux amount in number of counts less IR presence
D1 = data reading of Diode 1
D2 = data reading of Diode 2
n = 1.355. This is a fudge factor to scale back the sensitivity
up to ensure Equation 4 is valid.
k = 3.355. This is a scaling factor for the IR sensitive
Diode 2.
Flat Window Lens Design
A window lens will surely limit the viewing angle of the
ISL29004. The window lens should be placed directly on top
of the device. The thickness of the lens should be kept at
minimum to minimize loss of power due to reflection and
also to minimize loss of loss due to absorption of energy in
the plastic material. A thickness of t = 1mm is recommended
for a window lens design. The bigger the diameter of the
window lens the wider the viewing angle is of the ISL29001.
Table 16 shows the recommended dimensions of the optical
window to ensure both +35° and +45° viewing angle. These
D3
DESIGN PARAMETER
TABLE 15. SOLUTION2 SUMMARY TO EXAMPLE DESIGN
Gain/Range Mode
Transfer Function
=
# of clock cycles
n D1 kD2
(
R
FSR
T
EXT
int
–
PROBLEM
)
E
=
Range1 = 1000Lux
------------------------------- -
COUNTER
COUNTER = 1000
DATA
1000Lux
VALUE
100ms
100kΩ
×
1000Lux
December 21, 2006
(EQ. 15)
FN6221.0