DATASHEET

ISL29028
Features
The ISL29028 is an integrated ambient and infrared
light-to-digital converter with a built-in IR LED driver
and I2C Interface (SMBus Compatible). This device uses
two independent ADCs for concurrently measuring
ambient light and proximity in parallel. The flexible
interrupt scheme is designed for minimal
microcontroller utilization.
• Works Under All Light Sources Including Sunlight
• Dual ADCs Measure ALS/Prox Concurrently
• Intelligent Interrupt Scheme Simplifies μC Code
Ambient Light Sensing
• Simple Output Code Directly Proportional to lux
• 50Hz/60Hz Flicker Noise and IR Rejection
• Light Sensor Close to Human Eye Response
• Selectable 125/2000 Lux Range
Proximity Sensing
• Proximity Sensor with Broad IR Spectrum
- Can Use 850nm and 950nm External IR LEDs
• IR LED Driver with I2C Programmable Sink Currents
- Net 100μs Pulse with 110mA or 220mA Amplitudes
- Periodic Sleep Time up to 800ms Between Pulses
• Ambient IR Noise Cancellation (Including Sunlight)
Intelligent and Flexible Interrupts
• Independent ALS/Prox Interrupt Thresholds
• Adjustable Interrupt Persistency
- 1/4/8/16 Consecutive Triggers Required Before
Interrupt
Ultra Low Power
• 138μA DC Typical Supply Current for ALS/Prox Sensing
- 110μA for Sensors and Internal Circuitry
- 28μA Typical Current for External IR LED (Assuming
220mA for 100μs Every 800ms)
• <1.0μA Supply Current When Powered Down
Easy to Use
• Set Registers; Wait for Interrupt
• I2C (SMBus Compatible) Output
• Temperature Compensated
• Tiny ODFN8 2.0x2.1x0.7 (mm) Package
Additional Features
• 1.7V to 3.63V Supply for I2C Interface
• 2.25V to 3.63V Sensor Power Supply
• Pb-Free (RoHS compliant)
• I2C Address Selection Pin
For ambient light sensor (ALS) data conversions, an ADC
converts photodiode current (with a light sensitivity
range up to 2000 Lux) in 100ms per sample. The ADC
rejects 50Hz/60Hz flicker noise caused by artificial light
sources.
For proximity sensor (Prox) data conversions, the built-in
driver turns on an external infrared LED and the
proximity sensor ADC converts the reflected IR intensity
to digital. This ADC rejects ambient IR noise (such as
sunlight) and has a 540μs conversion time.
The ISL29028 provides low power operation of ALS and
proximity sensing with a typical 138μA normal operation
current (110μA for sensors and internal circuitry, ~28μA
for external LED) with 220mA current pulses for a net
100μs, repeating every 800ms (or under).
The ISL29028 uses both a hardware pin and software
bits to indicate an interrupt event has occurred. An ALS
interrupt is defined as a measurement which is outside a
set window. A proximity interrupt is defined as a
measurement over a threshold limit. The user may also
require that both ALS/prox interrupts occur at once, up
to 16 times in a row before activating the interrupt pin.
The ISL29028 is designed to operate from 2.25V to
3.63V over the -40°C to +85°C ambient temperature
range. It is packaged in a clear, lead-free 8 lead ODFN
package.
Pin Configuration
ISL29028
8 LD ODFN (2.0x2.1x0.7mm)
TOP VIEW
ADDR0
1
VDD
2
GND
3
REXT
4
THERMAL
PAD
8
IRDR
7
INT
6
SDA
5
SCL
*THERMAL PAD CAN BE CONNECTED TO GND OR
ELECTRICALLY ISOLATED
November 4, 2011
FN6780.2
1
Applications*(see page 15)
• Display and Keypad Dimming Adjustment and
Proximity Sensing for:
- Mobile Devices: Smart Phone, PDA, GPS
- Computing Devices: Laptop PC, Netbook
- Consumer Devices: LCD-TV, Digital Picture Frame,
Digital Camera
• Industrial and Medical Light and Proximity Sensing
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2010. All Rights Reserved.
I2C Bus is a registered trademark owned by NXP Semiconductors Netherlands, B.V.
All other trademarks mentioned are the property of their respective owners.
ISL29028
Low Power Ambient Light and Proximity Sensor
with Intelligent Interrupt and Sleep Modes
ISL29028
Ordering Information
PART NUMBER
(Notes 1, 2)
PACKAGE
TAPE AND REEL
(Pb-free)
TEMP. RANGE
(°C)
ISL29028IROZ-T7
-40 to +85
PKG.
DWG. #
8 Ld ODFN
L8.2.1x2.0
NOTES:
1. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets; molding compounds/die attach
materials and NiPdAu plate - e4 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free
soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed
the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL29028. For more information on MSL please
see techbrief TB363.
Pin Descriptions
PIN NUMBER
PIN NAME
DESCRIPTION
0
T.PAD
1
ADDR0
2
VDD
Positive supply: 2.25V to 3.63V
3
GND
Ground
4
REXT
External resistor (499kΩ; 1%) connects this pin to ground
5
SCL
I2C clock line
6
SDA
I2C data line
7
INT
Interrupt pin; Logic output (open-drain) for interrupt
8
IRDR
Thermal Pad (connect to GND or float)
I2C address pin - pull high or low (do not float)
The I2C bus lines can be pulled from 1.7V to above VDD, 3.63V
max
IR LED driver pin - current flows into ISL29028 from LED cathode
Block Diagram
VDD
2
ALS PHOTODIODE
ARRAY
COMMAND
REGISTER
LIGHT DATA
PROCESS
ALS AND IR
DUAL CHANNEL
ADCs
DATA
REGISTER
1
ADDR0
5
SCL
6
SDA
INTERRUPT
7
INT
IR DRIVER
8
IRDR
I2C
IR PHOTODIODE
ARRAY
IREF
FOSC
2
4
3
REXT
GND
FN6780.2
November 4, 2011
ISL29028
Absolute Maximum Ratings (TA = +25°C)
Thermal Information
VDD Supply Voltage between VDD and GND . . . . . . . . . .4.0V
I2C Bus Pin Voltage (SCL, SDA) . . . . . . . . . . . -0.5V to 4.0V
I2C Bus Pin Current (SCL, SDA) . . . . . . . . . . . . . . . . <10mA
REXT Pin Voltage . . . . . . . . . . . . . . . . -0.5V to VDD + 0.5V
IRDR Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.5V
ADDR0 Pin Voltage . . . . . . . . . . . . . . . -0.5V to VDD + 0.5V
INT Pin Voltage . . . . . . . . . . . . . . . . . . . . . . -0.5V to 4.0V
INT Pin Current . . . . . . . . . . . . . . . . . . . . . . . . . . . <10mA
ESD Rating
Human Body Model (Note 5) . . . . . . . . . . . . . . . . . . . 2kV
Thermal Resistance (Typical, Note 4)
θJA (°C/W)
8 Ld ODFN. . . . . . . . . . . . . . . . . . . . . . . . .
88
Maximum Die Temperature . . . . . . . . . . . . . . . . . . . +90°C
Storage Temperature . . . . . . . . . . . . . . . . -40°C to +100°C
Operating Temperature . . . . . . . . . . . . . . . -40°C to +85°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact
product reliability and result in failures not covered by warranty.
NOTES:
4. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach”
features. See Tech Brief TB379.
5. ESD on all pins is 2kV except for IRDR, which is 1.5kV.
IMPORTANT NOTE: All parameters having Min/Max specifications are guaranteed. Typical values are for information purposes only. Unless
otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: TJ = TC = TA
Electrical Specifications
PARAMETER
VDD
VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance.
DESCRIPTION
CONDITION
Power Supply Range
MIN TYP MAX UNIT
2.25
3.0
3.63
V
SR_VDD
Input Power-up Slew Rate
VDD Rising Edge between 0.4V and 2.25V
IDD_OFF
Supply Current when Powered Down
ALS_EN = 0; PROX_EN = 0
0.1
0.8
µA
Supply Current for ALS+Prox in Sleep Time
ALS_EN = 1; PROX_EN = 1
110
125
µA
ALS_EN = 0; PROX_EN = 1
80
µA
ALS_EN = 1; PROX_EN = 0
96
µA
5.25
MHz
IDD_NORM
IDD_PRX_SLP Supply Current for Prox in Sleep Time
IDD_ALS
fOSC
Supply Current for ALS
0.5
Internal Oscillator Frequency
tINTGR_ALS 12-bit ALS Integration/Conversion Time
88
tINTGR_PROX 8-bit Prox Integration/Conversion Time
DATAALS_0 ALS Result when Dark
EAMBIENT = 0 lux, 2k Range
DATAALS_F Full Scale ALS ADC Code
EAMBIENT > Selected Range Maximum Lux
(Note 9)
V/ms
100
112
ms
0.54
ms
1
Counts
4095 Counts
Ambient Light Sensing
±10
%
DATAALS_1 Light Count Output with LSB of
0.0326 lux/count
E = 53 lux, Fluorescent (Notes 6, 9),
ALS_RANGE = 0
1638
Counts
DATAALS_2 Light Count Output With LSB of
0.522 lux/count
E = 320 lux, Fluorescent (Note 6),
ALS_RANGE = 1
ΔDATA
DATA
Count Output Variation Over Three Light
Sources: Fluorescent, Incandescent and
Sunlight
460
DATAPROX_0 Prox Measurement w/o Object in Path
614
1
Counts
DATAPROX_F Full Scale Prox ADC Code
DATAPROX_1 Prox Measurement Result
768 Counts
255 Counts
(Note 7)
36
46
56
Counts
tr
Rise Time for IRDR Sink Current
RLOAD = 15Ω at IRDR pin, 20% to 80%
500
ns
tf
Fall time for IRDR Sink Current
RLOAD = 15Ω at IRDR pin, 80% to 20%
500
ns
IIRDR_0
IRDR Sink Current
PROX_DR = 0; VIRDR = 0.5V
IIRDR_1
IRDR Sink Current
PROX_DR = 1; VIRDR = 0.5V
3
95
110
220
125
mA
mA
FN6780.2
November 4, 2011
ISL29028
Electrical Specifications
PARAMETER
VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance. (Continued)
DESCRIPTION
CONDITION
IIRDR_LEAK IRDR Leakage Current
MIN TYP MAX UNIT
PROX_EN = 0; VDD = 3.63V (Note 8)
0.001
1
µA
4.3
V
VIRDR
Acceptable Voltage Range on IRDR Pin
tPULSE
Net IIRDR On Time Per PROX Reading
100
µs
VREF
Voltage of REXT Pin
0.51
V
FI2C
I2C Clock Rate Range
VI2C
Supply Voltage Range for I2C Interface
VIL
SCL and SDA Input Low Voltage
VIH
SCL and SDA Input High Voltage
Register bit PROX_DR = 0
0.5
1.7
400
kHz
3.63
V
0.55
V
1.25
V
ISDA
SDA Current Sinking Capability
VOL = 0.4V
3
5
mA
IINT
INT Current Sinking Capability
VOL = 0.4V
3
5
mA
(ΔIIRDR)/(ΔVIRDR)
PROX_DR = 0; VIRDR = 0.5V to 4.3V
4
mA/V
PSRRIRDR
NOTES:
6. An LED is used in production test. The LED irradiance is calibrated to produce the same DATA count against a fluorescent light
source of the same lux level.
7. An 850nm infrared LED is used to test PROX/IR sensitivity in an internal test mode.
8. Ability to guarantee IIRDR leakage of ~1nA is limited by test hardware.
9. For ALS applications under light-distorting glass, please see the section titled ALS Range 1 Considerations.
I2C Electrical Specifications For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1%
tolerance (Note 10).
PARAMETER
DESCRIPTION
VI2C
Supply Voltage Range for I2C Interface
fSCL
CONDITION
MIN
3.63
V
SCL Clock Frequency
400
kHz
VIL
SCL and SDA Input Low Voltage
0.55
V
VIH
SCL and SDA Input High Voltage
Vhys
Hysteresis of Schmitt Trigger Input
VOL
Low-level output voltage (open-drain) at
4mA sink current
Ii
1.7
TYP MAX UNIT
Input Leakage for each SDA, SCL pin
tSP
Pulse Width of Spikes that must be
Suppressed by the Input Filter
tAA
SCL Falling Edge to SDA Output Data Valid
1.25
V
0.05VDD
V
-10
Ci
Capacitance for each SDA and SCL pin
tHD:STA
Hold Time (Repeated) START Condition
After this period, the first clock pulse
is generated
tLOW
LOW Period of the SCL clock
Measured at the 30% of VDD
crossing
tHIGH
0.4
V
10
µA
50
ns
900
ns
10
pF
600
ns
1300
ns
HIGH period of the SCL Clock
600
ns
tSU:STA
Set-up Time for a Repeated START
Condition
600
ns
tHD:DAT
Data Hold Time
30
ns
tSU:DAT
Data Set-up Time
100
ns
20 + 0.1xCb
ns
tR
Rise Time of both SDA and SCL Signals
4
(Note 11)
FN6780.2
November 4, 2011
ISL29028
I2C Electrical Specifications For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1%
tolerance (Note 10). (Continued)
PARAMETER
tF
tSU:STO
tBUF
Cb
DESCRIPTION
CONDITION
Fall Time of both SDA and SCL Signals
(Note 11)
MIN
TYP MAX UNIT
20 + 0.1xCb
ns
600
ns
1300
ns
Set-up Time for STOP Condition
Bus Free Time Between a STOP and START
Condition
Capacitive Load for Each Bus Line
400
pF
Rpull-up
SDA and SCL system bus pull-up resistor
tVD;DAT
Data Valid Time
0.9
µs
tVD:ACK
Data Valid Acknowledge Time
0.9
µs
Maximum is determined by tR and tF
1
kΩ
VnL
Noise Margin at the LOW Level
0.1VDD
V
VnH
Noise Margin at the HIGH Level
0.2VDD
V
NOTES:
10. All parameters in I2C Electrical Specifications table are guaranteed by design and simulation.
11. Cb is the capacitance of the bus in pF.
FIGURE 1. I2C TIMING DIAGRAM
5
FN6780.2
November 4, 2011
ISL29028
Register Map
There are ten 8-bit registers accessible via I2C. Registers 0x1 and 0x2 define the operation mode of the device.
Registers 0x3 through 0x7 store the various ALS/IR/Prox thresholds which trigger interrupt events. Registers 0x8
through 0xA store the results of ALS/IR/Prox ADC conversions.
TABLE 1. ISL29028 REGISTERS AND REGISTER BITS
BIT
ADDR REG NAME
7
6
0x00
(n/a)
0x01
CONFIGURE
PROX EN
0x02
INTERRUPT
PROX_FLAG
0x03
PROX_LT
5
4
3
2
PROX_DR
ALS_EN
1
0
DEFAULT
(Reserved)
PROX_SLP[2:0]
PROX_PRST[1:0]
(Write 0)
(n/a)
ALS_FLAG
ALS_RANGE ALSIR_MODE
ALS_PRST[1:0]
INT_CTRL
PROX_LT[7:0]
0x00
0x00
0x00
0x04
PROX_HT
PROX_HT[7:0]
0xFF
0x05
ALSIR_TH1
ALSIR_LT[7:0]
0x00
0x06
ALSIR_TH2
0x07
ALSIR_TH3
0x08
PROX_DATA
PROX_DATA[7:0]
0x00
0x09
ALSIR_DT1
ALSIR_DATA[7:0]
0x00
0x0A
ALSIR_DT2
0x0E
TEST1
(Write as 0x00)
0x00
0x0F
TEST2
(Write as 0x00)
0x00
ALSIR_HT[3:0]
ALSIR_LT[11:8]
0xF0
ALSIR_HT[11:4]
0xFF
(Unused)
ALSIR_DATA[11:8]
0x00
Register Descriptions
TABLE 2. REGISTER 0x00 (RESERVED)
BIT #
ACCESS
DEFAULT
NAME
7:0
RO
(n/a)
(n/a)
FUNCTION/OPERATION
Reserved - no need to read or write
TABLE 3. REGISTER 0x01 (CONFIGURE) - PROX/ALS CONFIGURATION
BIT #
7
ACCESS DEFAULT
RW
0x00
NAME
FUNCTION/OPERATION
PROX_EN
(Prox Enable)
When = 0, proximity sensing is disabled
When = 1, continuous proximity sensing is enabled. Prox data will be ready
0.54ms after this bit is set high
6:4
RW
0x00
PROX_SLP
(Prox Sleep)
For bits 6:4 = (see the following)
111; sleep time between prox IR LED
110; sleep time between prox IR LED
101; sleep time between prox IR LED
100; sleep time between prox IR LED
011; sleep time between prox IR LED
010; sleep time between prox IR LED
001; sleep time between prox IR LED
000; sleep time between prox IR LED
3
RW
0x00
PROX_DR
(Prox Drive)
When = 0, IRDR behaves as a pulsed 110mA current sink
When = 1, IRDR behaves as a pulsed 220mA current sink
2
RW
0x00
ALS_EN
(ALS Enable)
When = 0, ALS/IR sensing is disabled
When = 1, continuous ALS/IR sensing is enabled with new data ready every
100ms
1
RW
0x00
ALS_RANGE
(ALS Range)
When = 0, ALS is in low-lux range
When = 1, ALS is in high-lux range
0
RW
0x00
pulses
pulses
pulses
pulses
pulses
pulses
pulses
pulses
is
is
is
is
is
is
is
is
0.0ms (run continuously)
12.5ms
50ms
75ms
100ms
200ms
400ms
800ms
ALSIR_MODE When = 0, ALS/IR data register contains visible ALS sensing data
(ALSIR Mode) When = 1, ALS/IR data register contains IR spectrum sensing data
6
FN6780.2
November 4, 2011
ISL29028
TABLE 4. REGISTER 0x02 (INTERRUPT) - PROX/ALS INTERRUPT CONTROL
BIT #
ACCESS DEFAULT
7
FLAG
0x00
BIT NAME
FUNCTION/OPERATION
PROX_FLAG
(Prox Flag)
When = 0, no Prox interrupt event has occurred since power-on or last “clear”
When = 1, a Prox interrupt event occurred. Clearable by writing “0”
6:5
RW
0x00
PROX_PRST
(Prox Persist)
4
RW
0x00
Unused
(Write 0)
3
FLAG
0x00
ALS_FLAG
(ALS FLAG)
2:1
RW
0x00
ALS_PRST
(ALS Persist)
0
RW
0x00
INT_CTRL
(Interrupt
Control)
For bits 6:5 = (see the following)
00; set PROX_FLAG if 1 conversion result trips the threshold value
01; set PROX_FLAG if 4 conversion results trip the threshold value
10; set PROX_FLAG if 8 conversion results trip the threshold value
11; set PROX_FLAG if 16 conversion results trip the threshold value
Unused register bit - write 0
When = 0, no ALS interrupt event has occurred since power-on or last “clear”
When = 1, an ALS interrupt event occurred. Clearable by writing “0”
For bits 2:1 = (see the following)
00; set ALS_FLAG if 1 conversion is outside the set window
01; set ALS_FLAG if 4 conversions are outside the set window
10; set ALS_FLAG if 8 conversions are outside the set window
11; set ALS_FLAG if 16 conversions are outside the set window
When = 0, set INT pin low if PROX_FLAG or ALS_FLAG high (logical OR)
When = 1, set INT pin low if PROX_FLAG and ALS_FLAG high (logical AND)
TABLE 5. REGISTER 0x03 (PROX_LT) - INTERRUPT LOW THRESHOLD FOR PROXIMITY SENSOR
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:0
RW
0x00
PROX_LT
(Prox Threshold)
8-bit interrupt low threshold for
proximity sensing
TABLE 6. REGISTER 0x04 (PROX_HT) - INTERRUPT HIGH THRESHOLD FOR PROXIMITY SENSOR
BIT #
7:0
ACCESS DEFAULT
RW
BIT NAME
PROX_HT
(Prox
Threshold)
0xFF
FUNCTION/OPERATION
8-bit interrupt high threshold for proximity sensing
TABLE 7. REGISTER 0x05 (ALSIR_TH1) - INTERRUPT LOW THRESHOLD FOR ALS/IR
BIT #
ACCESS
DEFAULT
BIT NAME
7:0
RW
0x00
ALSIR_LT[7:0]
(ALS/IR Low Thr.)
FUNCTION/OPERATION
Lower 8 bits (of 12 bits) for ALS/IR low interrupt threshold
TABLE 8. REGISTER 0x06 (ALSIR_TH2) - INTERRUPT LOW/HIGH THRESHOLDS FOR ALS/IR
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:4
RW
0x0F
ALSIR_HT[3:0]
Lower 4 bits (of 12 bits) for ALS/IR high interrupt threshold
(ALS/IR High Thr.)
3:0
RW
0x00
ALSIR_LT[11:8]
(ALS/IR Low Thr.)
Upper 4 bits (of 12 bits) for ALS/IR low interrupt threshold
TABLE 9. REGISTER 0x07 (ALSIR_TH3) - INTERRUPT HIGH THRESHOLD FOR ALS/IR
BIT #
ACCESS
DEFAULT
BIT NAME
7:0
RW
0xFF
ALSIR_HT[11:4]
(ALS/IR High Thr.)
7
FUNCTION/OPERATION
Upper 8 bits (of 12 bits) for ALS/IR high interrupt threshold
FN6780.2
November 4, 2011
ISL29028
TABLE 10. REGISTER 0x08 (PROX_DATA) - PROXIMITY SENSOR DATA
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:0
RO
0x00
PROX_DATA
(Proximity Data)
Results of 8-bit proximity sensor ADC conversion
TABLE 11. REGISTER 0x09 (ALSIR_DT1) - ALS/IR SENSOR DATA (LOWER 8 BITS)
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:0
RO
0x00
ALSIR_DATA
(ALS/IR Data)
Lower 8 bits (of 12 bits) from result of ALS/IR sensor conversion
TABLE 12. REGISTER 0x0A (ALSIR_DT2) - ALS/IR SENSOR DATA (UPPER 4 BITS)
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:4
RO
0x00
(Unused)
3:0
RO
0x00
ALSIR_DATA
(ALS/IR Data)
BIT #
ACCESS
DEFAULT
BIT NAME
7:0
RW
0x00
(Write as 0x00)
BIT #
ACCESS
DEFAULT
BIT NAME
7:0
RW
0x00
(Write as 0x00)
Unused bits.
Upper 4 bits (of 12 bits) from result of ALS/IR sensor conversion
TABLE 13. REGISTER 0x0E (TEST1) - TEST MODE
FUNCTION/OPERATION
Test mode register. When 0x00, in normal operation.
TABLE 14. REGISTER 0x0F (TEST2) - TEST MODE 2
I2C DATA
DEVICE ADDRESS
START
I2C SDA
MASTER
FUNCTION/OPERATION
Test mode register. When 0x00, in normal operation.
REGISTER ADDRESS
W A
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
I2C SDA
SLAVE (ISL29028)
SDA DRIVEN BY MASTER
I2C CLK
1
2
3
4
5
6
7
A
8
9
A
SDA DRIVEN BY MASTER
1
2
3
4
5
6
DEVICE ADDRESS
STOP START
7
8
9
A6 A5 A4 A3 A2 A1 A0 W
SDA DRIVEN BY MASTER
1
2
3
4
5
6
DATA BYTE0
A
SDA DRIVEN BY ISL29028
A
A D7 D6 D5 D4 D3 D2 D1 D0
7
8
9
1
2
3
4
5
6
7
8
9
FIGURE 2. I2C DRIVER TIMING DIAGRAM FOR MASTER AND SLAVE CONNECTED TO COMMON BUS
Principles of Operation
I2C Interface
The ISL29028’s I2C interface slave address is internally
hardwired as 0b100010<x>, where “0b” signifies binary
notation and x represents the logic level on pin ADDR0.
Figure 2 shows a sample one-byte read. The I2C bus
master always drives the SCL (clock) line, while either
the master or the slave can drive the SDA (data) line.
Every I2C transaction begins with the master asserting a
start condition (SDA falling while SCL remains high). The
first transmitted byte is initiated by the master and
includes 7 address bits and a R/W bit. The slave is
responsible for pulling SDA low during the ACK bit after
every transmitted byte.
Each I2C transaction ends with the master asserting a
stop condition (SDA rising while SCL remains high).
8
For more information about the I2C standard, please
consult the Philips™ I2C specification documents.
Photodiodes and ADCs
The ISL29028 contains two photodiode arrays which
convert photons (light) into current. The ALS
photodiodes are constructed to mimic the human eye’s
wavelength response curve to visible light (see Figure 6).
The ALS photodiodes’ current output is digitized by a
12-bit ADC in 100ms. These 12 bits can be accessed by
reading from I2C registers 0x9 and 0xA when the ADC
conversion is completed.
The ALS converter is a charge-balancing integrating
12-bit ADC. Charge-balancing is best for converting small
current signals in the presence of periodic AC noise.
Integrating over 100ms highly rejects both 50Hz and
60Hz light flicker by picking the lowest integer number of
cycles for both 50Hz/60Hz frequencies.
FN6780.2
November 4, 2011
ISL29028
ALS CONVERSION TIME =
100ms (FIXED)
SEVERAL µs BETWEEN
CONVERSIONS
ALS
ACTIVE
100ms
PROX
SENSOR
ACTIVE
100ms
100ms
100ms
100ms
TIME
0.54ms FOR PROX
CONVERSION
TIME
IRDR
(CURRENT
DRIVER)
SERIES OF
CURRENT PULSES
TOTALING 0.1ms
TIME
SLEEP TIME
(PROX_SLP)
FIGURE 3. TIMING DIAGRAM FOR PROX/ALS EVENTS - NOT TO SCALE
The proximity sensor is an 8-bit ADC which operates in a
similar fashion. When proximity sensing is enabled, the
IRDR pin will drive a user-supplied infrared LED, the
emitted IR reflects off an object (i.e., a human head) back
into the ISL29028, and a sensor converts the reflected IR
wave to a current signal in 0.54ms. The ADC subtracts
the IR reading before and after the LED is driven (to
remove ambient IR such as sunlight), and converts this
value to a digital count stored in Register 0x8.
The ISL29028 is designed to run two conversions
concurrently: a proximity conversion and an ALS (or IR)
conversion. Please note that because of the conversion
times, the user must let the ADCs perform one full
conversion first before reading from I2C Registers
PROX_DATA (wait 0.54ms) or ALSIR_DT1/2 (wait 100ms).
The timing between ALS and Prox conversions is arbitrary
(as shown in Figure 3). The ALS runs continuously with
new data available every 100ms. The proximity sensor
runs continuously with a time between conversions
decided by PROX_SLP (Register 1 Bits [6:4]).
Ambient Light and IR Sensing
The ISL29028 is set for ambient light sensing when
Register bit ALSIR_MODE = 0 and ALR_EN = 1. The
light-wavelength response of the ALS appears as shown
in Figure 6. ALS measuring mode (as opposed to IR
measuring mode) is set by default.
When the part is programmed for infrared (IR) sensing
(ALSIR_MODE = 1; ALS_EN = 1), infrared light is
converted into a current and digitized by the same ALS
ADC. The result of an IR conversion is strongly related to
the amount of IR energy incident on our sensor, but is
unitless and is referred to in digital counts.
Proximity Sensing
When proximity sensing is enabled (PROX_EN = 1), the
external IR LED is driven for 0.1ms by the built-in IR LED
driver through the IRDR pin. The amplitude of the IR LED
9
current depends on Register 1 bit 3: PROX_DR. If this bit
is low, the load will see a fixed 110mA current pulse. If
this bit is high, the load on IRDR will see a fixed 220mA
current pulse as seen in Figure 4.
220mA
(PROX_DR = 1)
110mA
(PROX_DR = 0)
PIN 8 - IRDR
(IRDR IS HI-Z WHEN
NOT DRIVING)
FIGURE 4. CURRENT DRIVE MODE OPTIONS
When the IR from the LED reaches an object and gets
reflected back into the ISL29028, the reflected IR light is
converted into current as per the IR spectral response
shown in Figure 7. One entire proximity measurement
takes 0.54ms for one conversion (which includes 0.1ms
spent driving the LED), and the period between proximity
measurements is decided by PROX_SLP (sleep time) in
Register 1 Bits 6:4.
Average LED driving current consumption is given by
Equation 1.
I lRDR ;PEAK × 100μs
I lRDR ;AVE = -------------------------------------------------------T SLEEP
(EQ. 1)
A typical IRDR scheme is 220mA amplitude pulses every
800ms, which yields 28μA DC.
Total Current Consumption
Total current consumption is the sum of IDD and IIRDR.
The IRDR pin sinks current (as shown in Figure 4) and
the average IRDR current can be calculated using
Equation 1 above. IDD depends on voltage and the
mode-of-operation as seen in Figure 11.
FN6780.2
November 4, 2011
ISL29028
Interrupt Function
The ISL29028 has an intelligent interrupt scheme
designed to shift some logic processing away from
intensive microcontroller I2C polling routines (which
consume power) and towards a more independent light
sensor which can instruct a system to “wake up” or “go
to sleep”.
An ALS interrupt event (ALS_FLAG) is governed by
Registers 5 through 7. The user writes a high and low
threshold value to these registers and the ISL29028 will
issue an ALS interrupt flag if the actual count stored in
Registers 0x9 and 0xA are outside the user’s programmed
window. The user must write 0 to clear the ALS_FLAG.
A proximity interrupt event (PROX_FLAG) is governed by
the high and low thresholds in registers 3 and 4
(PROX_LT and PROX_HT). PROX_FLAG is set when the
measured proximity data is more than the higher
threshold X-times-in-a-row (X is set by user; see next
paragraph). The proximity interrupt flag is cleared when
the prox data is lower than the low proximity threshold
X-times-in-a-row, or when the user writes “0” to
PROX_FLAG.
Interrupt persistency is another useful option available
for both ALS and proximity measurements. Persistency
requires X-in-a-row interrupt flags before the INT pin is
driven low. Both ALS and Prox have their own
independent interrupt persistency options. See
ALS_PRST and PROX_PRST bits in Register 2.
The final interrupt option is the ability to AND or OR the
two interrupt flags using Register 2 Bit 0 (INT_CTRL). If
the user wants both ALS/Prox interrupts to happen at the
same time before changing the state of the interrupt pin,
set this bit high. If the user wants the interrupt pin to
change state when either the ALS or the Proximity
interrupt flag goes high, leave this bit to its default of 0.
ALS Range 1 Considerations
When measuring ALS counts higher than 1800 on range
1 (ALSIR_MODE = 0, ALS_RANGE = 0, ALS_DATA >
1800), switch to range 2 (change the ALS_RANGE bit
from “0” to “1”) and remeasure ALS counts. This
recommendation pertains only to applications where the
light incident upon the sensor is IR-heavy and is distorted
by tinted glass that increases the ratio of infrared to
visible light. For more information, see the separate ALS
Range 1 Considerations document.
VDD Power-up and Power Supply
Considerations
Upon power-up, please ensure a VDD slew rate of
0.5V/ms or greater. After power-up, or if the user’s power
supply temporarily deviates from our specification (2.25V
to 3.63V), Intersil recommends the user write the
following: write 0x00 to register 0x01, write 0x29 to
register 0x0F, write 0x00 to register 0x0E, and write 0x00
to register 0x0F. The user should then wait ~1ms or more
and then rewrite all registers to the desired values. If the
user prefers a hardware reset method instead of writing
10
to test registers: set VDD = 0V for 1 second or more,
power back up at the required slew rate, and write
registers to the desired values.
Power-Down
To put the ISL29028 into a power-down state, the user
can set both PROX_EN and ALS_EN bits to 0 in Register 1.
Or more simply, set all of Register 1 to 0x00.
Calculating Lux
The ISL29028’s ADC output codes are directly proportional
to lux when in ALS mode (see ALSIR_MODE bit).
(EQ. 2)
E calc = α RANGE × OUT ADC
In Equation 2, Ecalc is the calculated lux reading and OUT
represents the ADC code. The constant α to plug in is
determined by the range bit ALS_RANGE (register 0x1
bit 1) and is independent of the light source type.
TABLE 15. ALS SENSITIVITY AT DIFFERENT RANGES
ALS_RANGE
αRANGE
(Lux/Count)
0
0.0326
1
0.522
Table 15 shows two different scale factors: one for the
low range (ALS_RANGE = 0) and the other for the high
range (ALS_RANGE = 1).
Noise Rejection
Charge balancing 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...ki) is zero. Similarly, setting the
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. Since wall sockets
may output at 60Hz or 50Hz, our integration time is
100ms: the lowest common integer number of cycles for
both frequencies.
Proximity Detection of Various Objects
Proximity sensing relies on the amount of IR reflected
back from objects. A perfectly black object would
absorb all light and reflect no photons. The ISL29028 is
sensitive enough to detect black ESD foam which
reflects only 1% of IR. For biological objects, blonde
hair reflects more than brown hair and customers may
notice that skin tissue is much more reflective than hair.
IR penetrates into the skin and is reflected or scattered
back from within. As a result, the proximity count peaks
at contact and monotonically decreases as skin moves
away. The reflective characteristics of skin are very
different from that of paper.
FN6780.2
November 4, 2011
ISL29028
Typical Circuit
Suggested PCB Footprint
A typical application for the ISL29028 is shown in
Figure 5. The ISL29028’s I2C address is internally
hardwired as 0b100010<x>, with x representing the
logic state of input I2C address pin ADDR0. The device
can be tied onto a system’s I2C bus together with other
I2C compliant devices.
It is important that users check the “Surface Mount
Assembly Guidelines for Optical Dual FlatPack No Lead
(ODFN) Package” before starting ODFN product board
mounting.
Soldering Considerations
Convection heating is recommended for reflow soldering;
direct-infrared heating is not recommended. The plastic
ODFN package does not require a custom reflow
soldering profile, and is qualified to +260°C. A standard
reflow soldering profile with a +260°C maximum is
recommended.
(http://www.intersil.com/data/tb/TB477.pdf)
(http://www.intersil.com/data/tb/TB477.pdf)
Layout Considerations
The ISL29028 is relatively insensitive to layout. Like
other I2C devices, it is intended to provide excellent
performance even in significantly noisy environments.
There are only a few considerations that will ensure best
performance.
Route the supply and I2C traces as far as possible from all
sources of noise. A 0.1µF and 1µF power supply decoupling
capacitors need to be placed close to the device.
VI2C_PULL-UP
R1
10kΩ
R2
10kΩ
I2C MASTER
R3
10kΩ
MICROCONTROLLER
INT
SDA
SCL
VDD
VIR-LED
SLAVE_0
1
2
C1
1µF
C2
0.1µF
3
4
ADDR0 IRDR
VDD
INT
GND
SDA
REXT
SCL
SLAVE_1
8
7
I2C SLAVE_n
SDA
SDA
SCL
SCL
6
5
REXT ISL29028
499kΩ
FIGURE 5. ISL29028 TYPICAL CIRCUIT
11
FN6780.2
November 4, 2011
ISL29028
Typical Performance Curves
VDD = 3.0V, REXT = 499kΩ
1.0
1.0
0.9
FLUORESCENT
NORMALIZED RESPONSE
NORMALIZED INTENSITY
0.8
0.7
0.6
HALOGEN
0.5
INCAND.
SUN
0.4
HUMAN EYE
0.9
0.3
0.2
0.1
0.8
IR/PROX
ALS
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
350
550
750
0.0
300
950
400
500
WAVELENGTH (nm)
FIGURE 6. SPECTRUM OF FOUR LIGHT SOURCES
NORMALIZED BY LUMINOUS INTENSITY
(LUX)
800
900
1000
1100
2500
LUX METER READING (LX)
0.9
NORMALIZED SENSITIVITY
700
FIGURE 7. ISL29028 SENSITIVITY TO DIFFERENT
WAVELENGTHS
1.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
HALOGEN
2000
1500
FLUORESCENT
1000
INCANDESCENT
500
0.1
0
0
-90
-60
-30
0
30
60
90
0
1000
2000
4000
5000
FIGURE 9. ALS LINEARITY OVER 3 LIGHT SOURCES
(2000 LUX RANGE)
FIGURE 8. ANGULAR SENSITIVITY
300
160
ALS+PROX (DURING PROX SLEEP)
18% GREY CARD
140
MEASURED IDD (µA)
250
220mA MODE
200
110mA MODE
150
100
WHITE COPY PAPER
50
0
3000
ALS CODE (12-BIT)
ANGULAR OFFSET (°)
PROX COUNTS (8-BIT)
600
WAVELENGTH (nm)
ALS-ONLY
120
100
80
PROX (DURING PROX SLEEP)
60
0
20
40
60
80 100 120
DISTANCE (mm)
140
160
180
200
FIGURE 10. PROX COUNTS vs DISTANCE WITH 10CM x
10CM REFLECTOR (USING ISL29028
EVALUATION BOARD)
12
40
2.25
2.40
2.55
2.70
2.85 3.00 3.15
INPUT VDD (V)
3.30
3.45 3.60
FIGURE 11. VDD vs IDD FOR VARIOUS MODES OF
OPERATION
FN6780.2
November 4, 2011
ISL29028
Typical Performance Curves
VDD = 3.0V, REXT = 499kΩ (Continued)
50
240
40
220
ALS COUNT CHANGE FROM
+25°C MEASUREMENT (%)
220mA-MODE (PROX_DR = 1)
180
160
140
120
100
110mA-MODE (PROX_DR = 0)
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
20
10
0
-10
-20
-30
-40
-50
-40
5.0
-15
VIRDR (V)
FIGURE 12. IRDR PULSE AMPLITUDE vs VIRDR
10
35
TEMPERATURE (°C)
60
85
FIGURE 13. STABILITY OF ALS COUNT OVER TEMP
(AT 300 LUX)
10
9
8
ALS CODE (12-BIT)
IIRDR (A)
200
30
7
6
5
4
3
2
1
0
-40
10
60
TEMPERATURE (°C)
FIGURE 14. STABILITY OF ALS COUNT OVER-TEMPERATURE (AT 0.00 LUX)
13
FN6780.2
November 4, 2011
ISL29028
2.00
SENSOR OFFSET
2.10
0.43
1
8
2
7
3
6
0.50
4
5
0.42
FIGURE 15. 8 LD ODFN SENSOR LOCATION OUTLINE - DIMENSIONS IN mm
14
FN6780.2
November 4, 2011
ISL29028
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to
web to make sure you have the latest Rev.
DATE
REVISION
CHANGE
11/11/10
FN6780.2
Updates to test methodology, addition of "ALS Range 1 Considerations" paragraph, updates to
"Power-Up" Sequence, test register clarification
3/2/10
FN6780.1
Typo fixes and sensitivity updates
3/2/10
FN6780.0
Initial release.
Products
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The
Company's products address some of the industry's fastest growing markets, such as, flat panel displays, cell phones,
handheld products, and notebooks. Intersil's product families address power management and analog signal
processing functions. Go to www.intersil.com/products for a complete list of Intersil product families.
*For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device
information page on intersil.com: ISL29028
To report errors or suggestions for this datasheet, please go to www.intersil.com/askourstaff
FITs are available from our website at http://rel.intersil.com/reports/search.php
For additional products, see www.intersil.com/product_tree
Intersil products are manufactured, assembled and tested utilizing ISO9000 quality systems as noted
in the quality certifications found at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications
at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by
Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any
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patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
15
FN6780.2
November 4, 2011
ISL29028
Package Outline Drawing
L8.2.1x2.0
8 LEAD OPTICAL DUAL FLAT NO-LEAD PLASTIC PACKAGE (ODFN)
Rev 1, 12/09
2.10
A
B
6
6
PIN 1
INDEX AREA
PIN 1
INDEX AREA
0.50
2.00
1.50
1.50
0.20±0.05
(2X)
0.10 M C A B
0.10
8X 0 . 35 ± 0 . 05
TOP VIEW
0.75
BOTTOM VIEW
SEE DETAIL "X"
2.50
0.10 C
2.10
0.70±0.05
C
BASE PLANE
SEATING PLANE
0.08 C
SIDE VIEW
(6x0.50)
(1.50)
(8x0.20)
C
(8x0.20)
5
0 . 00 MIN.
0 . 05 MAX.
(8x0.55)
DETAIL "X"
(0.75)
TYPICAL RECOMMENDED LAND PATTERN
0 . 2 REF
NOTES:
1.
Dimensions are in millimeters.
Dimensions in ( ) for Reference Only.
2.
Dimensioning and tolerancing conform to ASME Y14.5m-1994.
3.
Unless otherwise specified, tolerance : Decimal ± 0.05
4.
Dimension b applies to the metallized terminal and is measured
between 0.25mm and 0.35mm from the terminal tip.
5.
Tiebar shown (if present) is a non-functional feature.
6.
The configuration of the pin #1 identifier is optional, but must be
located within the zone indicated. The pin #1 identifier may be
either a mold or mark feature.
16
FN6780.2
November 4, 2011
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