ISL29011IROZ-T7 Intersil, ISL29011IROZ-T7 Datasheet - Page 10

• Manufacturer Part Number: ISL29011IROZ-T7
• Description: IC PROXIMITY SENSOR AMB LT 8ODFN
• Manufacturer: Intersil

Specifications of ISL29011IROZ-T7

• Output Type: Digital - I²C
• Sensor Type: Light and Proximity
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ISL29011IROZ-T7TR

Registers 06 and 07 hex set the high (HI) threshold for the
interrupt pin and the interrupt flag. 06 hex is the LSB and 07
hex is the MSB. By default, the Interrupt threshold HI is FF
hex for both LSB and MSB.
Test Register (08 hex)
Register 8 is a reserved register that holds 00h during
normal operation.
Calculating Lux
The ISL29011’s ADC output codes, DATA, are directly
proportional to lux in the ambient light sensing.
Here, E
determined by the Full Scale Range and the ADC’s
maximum output counts. The constant is independent on the
light sources (fluorescent, incandescent and sunlight)
because of the light sources’ IR component is removed
during the light signal process. The constant can also be
viewed as the sensitivity: the smallest lux measurement the
device can measure as shown in Equation 2.
α
Here, Range(k) is defined in Table 9. Count
maximum output counts from the ADC.
The transfer function used for n-bit ADC becomes
Equation 3:
Here, n = 4, 8, 12 or 16. This is the number of ADC bits
programmed in the command register. 2
maximum number of counts possible from the ADC output.
Data is the ADC output stored in the data registers (02 hex
and 03 hex).
Integration and Conversion Time
The ADC resolution and f
time, t
t
where n is the number of bits of resolution and n = 4, 8, 12 or
16. 2
programmed at the command register 01(hex) bits 3 and 2.
E
E
**Recommended R
int
cal
cal
R
499**
=
(kΩ)
250
EXT
=
----------------------------
Count
Range k ( )
=
n
=
2
, therefore, is the number of clock cycles. n can be
int
n
Range k ( )
---------------------------
α
cal
TABLE 11. INTEGRATION TIME OF n-BIT ADC
×
as shown in Equation 4.
×
------------- -
f
max
DATA
n = 16-BIT
is the calculated lux reading. The constant α is
2
OSC
n
1
(ms)
45
90
=
×
EXT
2
DATA
n
×
resistor value
--------------------------------------------- -
725kHz
n = 12-BIT
OSC
2.812
(ms)
5.63
R
10
EXT
×
determines the integration
499kΩ
n = 8-BIT
175.5
(µs)
351
n
represents the
max
is the
n = 4-BIT
10.8µs
21.6µs
(µs)
(EQ. 3)
(EQ. 1)
(EQ. 2)
(EQ. 4)
ISL29011
External Scaling Resistor R
The ISL29011 uses an external resistor R
internal oscillator frequency, f
range, Range. f
R
referenced to 499kΩ as shown in Equations 5 and 6:
Noise Rejection
In general, integrating type ADC’s have excellent
noise-rejection characteristics for periodic noise sources
whose frequency is an integer multiple of the conversion
rate. For instance, a 60Hz AC unwanted signal’s sum from
0ms to k*16.66ms (k = 1,2...k
device’s integration time to be an integer multiple of the
periodic noise signal, greatly improves the light sensor
output signal in the presence of noise.
ADC Output in IR Sensing
The ISL29011’s ADC output codes, DATA, are directly
proportional to the IR intensity received in the IR sensing.
Here, E
changes with the spectrum of background IR noise like
sunlight and incandescent light. The β also changes with the
ADC’s range and resolution selections.
ADC Output in Proximity Sensing
In the proximity sensing, the ADC output codes, DATA, are
directly proportional to the total IR intensity from the
background IR noise and from the IR LED driven by the
ISL29011.
Here, β and E
The constant γ depends on the spectrum of the used IR LED
and the ADC’s range and resolution selections. E
IR intensity which is emitted from the IR LED and reflected
by a specific objector to the ISL29011. E
current to the IR LED and the surface of the object. E
decreases with the square of the distance between the
object and the sensor.
If background IR noise is small, E
the ADC output directly decreases with the distance. If there
is significant background IR noise, ISL29011 offers two
schemes to reduce the effect. The first way is do a proximity
sensing using Scheme 0, immediately followed by an IR
sensing. The differential reading of ADC outputs from the
proximity and IR sensing will then reduce the effect of
background IR noise and directly decrease with the distance
between the object and the sensor. The second way is to do
Range
f
DATA
DATA
OSC
EXT
. For user simplicity, the proportionality constant is
=
IR
PROX
IR
=
499kΩ
----------------- -
R
=
499kΩ
----------------- -
EXT
is the received IR intensity. The constant β
R
β
EXT
=
×
IR
E
β
×
OSC
IR
×
have the same meanings as in Equation 7.
×
725
E
Range k ( )
IR
kHz
and Range are inversely proportional to
+
γ
×
E
LED
OSC
i
) is zero. Similarly, setting the
EXT
IR
and the light sensing
can be neglected, and
for f
LED
OSC
EXT
depends on the
to fix its
and Range
February 4, 2010
LED
LED
(EQ. 6)
FN6467.3
(EQ. 7)
(EQ. 8)
(EQ. 5)
is the