ISL29021IROZ-T7 Intersil, ISL29021IROZ-T7 Datasheet - Page 7

• Manufacturer Part Number: ISL29021IROZ-T7
• Description: IC SENSOR LIGHT-DGTL I2C 8ODFN
• Manufacturer: Intersil

Specifications of ISL29021IROZ-T7

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

.
.
Data Registers (02 hex and 03 hex)
The device has two 8-bit read-only registers to hold the data
from LSB to MSB for ADC. The most significant bit (MSB) is
accessed at 03 hex, and the least significant bit (LSB) is
accessed at 02 hex. For 16-bit resolution, the data is from
D0 to D15; for 12-bit resolution, the data is from D0 to D11;
for 8-bit resolution, the data is from D0 to D7. The registers
are refreshed after every conversion cycle.
Interrupt Registers (04, 05, 06 and 07 hex)
Registers 04 and 05 hex set the low (LO) threshold for the
interrupt pin and the interrupt flag. 04 hex is the LSB and 05
hex is the MSB. By default, the Interrupt threshold LO is 00
hex for both LSB and MSB.
4. Resolution: Bits 3 and 2. Bits 3 and 2 determine the ADC’s
5. Range: Bits 1 and 0. The Full Scale Range (FSR) can be
BITS 5 TO 4
ADDRESS
BITS 1:0
BITS 3 TO 2
TABLE 7. CURRENT SOURCE CAPABILITY AT IRDR PIN
resolution and the number of clock cycles per conversion
in Internal Timing Mode. Changing the number of clock
cycles does more than just change the resolution of the
device. It also changes the integration time, which is the
period the device’s analog-to-digital (A/D) converter
samples the photodiode current signal for a measurement.
adjusted via I
possible values of FSR for the 499kΩ R
(hex)
00
01
10
11
02
03
00
01
10
11
00
01
10
11
D0 is LSB for 4, 8, 12 or 16-bit resolution, D3 is MSB
for 4-bit resolution, D7 is MSB for 8-bit resolution
D15 is MSB for 16-bit resolution, D11 is MSB for
12-bit resolution
k
1
2
3
4
12.5mA IR LED driver
25mA IR LED driver
50mA IR LED driver
100mA IR LED driver
TABLE 8. RESOLUTION/WIDTH
2
2
2
2
NUMBER OF CLOCK CYCLES
TABLE 10. DATA REGISTERS
16
12
8
4
2
= 256
= 16
C using Bits 1 and 0. Table 9 lists the
TABLE 9. RANGE/FSR
= 65,536
= 4,096
RANGE(k)
IRDR PIN SOURCE CURRENT
Range1
Range2
Range3
Range4
7
CONTENTS
FSR @ IR SENSING
Refer to page 3
Refer to page 3
Refer to page 3
Refer to page 3
EXT
n-BIT ADC
resistor.
16
12
8
4
ISL29021
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.
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.
External Scaling Resistor R
Range
The ISL29021 uses an external resistor R
internal oscillator frequency, f
are inversely proportional to R
proportionality constant is referenced to 499kΩ:
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 proximity sensor
output signal in the presence of noise.
ADC Output in IR Sensing
The ISL29021’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
Range
f
DATA
int
**Recommended R
OSC
R
499**
(kΩ)
250
EXT
=
n
2
=
int
, therefore, is the number of clock cycles. n can be
IR
n
IR
=
499kΩ
----------------- -
.
TABLE 11. INTEGRATION TIME OF n-BIT ADC
×
R
=
499kΩ
----------------- -
------------- -
f
EXT
is the received IR intensity. The constant β
R
n = 16-BIT
OSC
β
1
EXT
×
45ms
90ms
E
×
IR
=
725
×
EXT
2
Range k ( )
n
kHz
×
resistor value
--------------------------------------------- -
725kHz
n = 12-BIT
2.812ms
5.63ms
OSC
R
EXT
OSC
i
) is zero. Similarly, setting the
EXT
×
determines the integration
499kΩ
EXT
. Range. f
. For user simplicity, the
n = 8-BIT
175.5µs
for f
351µs
EXT
OSC
OSC
to fix its
and
and Range
n = 4-BIT
March 3, 2009
10.8µs
21.6µs
FN6732.0
(EQ. 4)
(EQ. 2)
(EQ. 3)
(EQ. 1)