DATASHEET

DATASHEET
Low Power Ambient Light and Proximity Sensor with
Enhanced Infrared Rejection
ISL29038
Features
The ISL29038 is a low power Ambient Light Sensor (ALS) and
proximity (PROX) sensor. It has a built-in IR-LED driver for
proximity function. The ALS function measures the amount of
light (in the visible spectrum) incident on the ISL29038.
• Ideal for applications under dark or tinted glass
The ALS function has a programmable ambient IR-rejection,
which allows fine tuning of light source variations and is ideal
for light sensor applications under dark protective glass. The
ALS provides a 12-bit measurement. A passive optical filter
removes unwanted wavelengths (IR or Ultraviolet) to ensure
accurate ALS measurement.
The proximity function includes a new offset adjustment to
compensate for the IR light reflected off the inside of the
protective glass cover and back to the ISL29038 sensor. This
offset adjustment allows the sensor to compensate for these
internal reflections and preserve the dynamic range of the
proximity measurement.
The built-in current-driver pulses an external infrared LED at a
programmed current for 90µs. The infrared light that is
reflected and received by ISL29038 is digitized by an 8-bit
ADC. The proximity sensor also has a passive optical filter
designed to pass IR and reject visible wavelengths.
The ISL29038 provides a hardware pin to indicate an interrupt
event. The interrupt pin saves power as the host microcontroller
can ‘wake-up’ on an interrupt event and does not need to poll
the device for an interrupt event. The interrupt generator is
user configurable and provides several options for ALS and
PROX trigger configurations. The ISL29038 supports an
SMBus compatible I2C interface for configuration and control.
• Enhanced ambient sunlight rejection to 40k Lux
• Programmable proximity sleep time between proximity
measurements optimizes power consumption
• Hardware interrupt - no polling required
• Programmable IR compensation to fine tune ALS
performance for various glass compositions
• Up to 4000 Lux, four selectable ALS ranges
• Programmable IR LED drive current to 250mA
• Operates from 2.25V to 3.63V VDD
• Power-down IDD, typical 0.2µADC
• Tiny 2.1x2.0x0.7 (mm) ODFN package
Applications
• Display dimming and adjustment
- Mobile devices: smart phones, PDA, GPS
- Computing: monitors, laptops, notebooks
- Picture frames, tablet_PCs, LCD_TV
• Object detection
- Touchscreen disabling
- Smart power-saving
100
90
VDD_IRLED
R2
100
VDD_ANALOG
C2
1µF
C1
1µF
D1
IRLED
U1
1
8
GNDIR IRDR
2
7
AVDD
INT
3
6
SDA
AGND
4
5
SCL
REXT
SCL, SDA AND
INT PULL UPs
SMBus MASTER
INT
SDA
SCL
R1 ISL29038
499k
R1: 499k 1% RESISTOR
R2: 100Ω 5% RESISTOR
C1, C2: 1µF CERAMIC 10V CAPACITOR
D1: OSRAM SFH4650 INFRARED LED
FIGURE 1. TYPICAL APPLICATIONS CIRCUIT
January 23, 2015
FN7851.1
1
FULL-SCALE RANGE (%)
VDD_PULLUP
80
250mA
70
125mA
60
50
62.5mA
40
30
31.25mA
20
10
0
0
20
40
60
18% GREY CARD PROXIMITY DISTANCE (mm)
80
FIGURE 2. PROXIMITY SENSITIVITY
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2012, 2014. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
ISL29038
VDD
2
ALS PHOTODIODE
ARRAY
COMMAND
REGISTER
PHOTODIODE
AMPLIFIERS
(ALS AND IR)
DUAL CHANNEL
ADCs
DATA
REGISTER
1
I2C
IR PHOTODIODE
ARRAY
SCL
6
SDA
INTERRUPT
7
INT
IR DRIVER
8
IRDR
IREF
FOSC
4
3
REXT
GND
GNDIR
5
FIGURE 3. ISL29038 BLOCK DIAGRAM
Pin Configuration
Pin Description
ISL29038
(8 LD ODFN)
TOP VIEW
GNDIR
1
8
IRDR
VDD
2
7
INT
GND
3
6
SDA
REXT
THERMAL
PAD
4
5
SCL
PIN#
NAME
DESCRIPTION
1
GNDIR
2
VDD
Positive supply: 2.25V to 3.63V.
3
GND
Ground.
4
REXT
External Resistor, Connect to GND pin through a
499kΩ 1% resistor.
5
SCL
I2C Serial Clock Input.
6
SDA
I2C Serial Data Input/Output.
7
INT
Active Low, Open-Drain Output.
8
IRDR
IR-LED Driver Sink - Connect to IR LED Cathode.
-
TPAD
Thermal Pad - Connect to GND.
Ground for IRDR LED Current.
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
PART
MARKING
ISL29038IROZ-T7
N/A
ISL29038IROZ-EVALZ
Evaluation Board
VDD RANGE
(V)
TEMP RANGE
(°C)
2.25 to 3.63
-40 to +85
PACKAGE
8 Lead ODFN
PKG.
DWG. #
L8.2.1x2.0
NOTES:
1. 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), see device information page for ISL29038. For more information on MSL see techbrief TB477.
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ISL29038
Absolute Maximum Ratings
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
INT Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 4.0V
INT Pin Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <10mA
ESD Rating
Human Body Model (Note 6). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Thermal Resistance (Typical)
JA (°C/W) JC (°C/W)
8 Ld ODFN (Notes 4, 5) . . . . . . . . . . . . . . . .
88
14
Maximum Die Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +90°C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to +100°C
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Pb-Free Reflow Profile (*) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see TB477
*Peak temperature during solder reflow +260°C max
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. JA 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. For JC, the “case temp” location is the center of the exposed metal pad on the package underside.
6. Tested per JESD22-A114E, ESD on all pins is 2kV except IRDR, which is 1.5kV.
Electrical Specifications
PARAMETER
VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance.
DESCRIPTION
TEST CONDITION
MAX
(Note 7) UNITS
MIN
(Note 7)
TYP
2.25
3.0
3.63
V
INPUT POWER
VDD
IDD_OFF
IDD_NORM
IDD_PRX_SLP
IDD_ALS
Power Supply Range
Supply Current when Powered Down
ALS_EN = 0; PROX_EN = 0
0.2
1.0
µA
Supply Current for ALS+Prox in Sleep Time
ALS_EN = 1; PROX_EN = 1
125
140
µA
Supply Current for Prox in Sleep Time
ALS_EN = 0; PROX_EN = 1
95
µA
Supply Current for ALS
ALS_EN = 1; PROX_EN = 0
95
µA
ADC (ALS AND PROX)
tINTGR_ALS
12-bit ALS Conversion Time
80
95
110
ms
tINTGR_PROX
8-bit Prox Conversion Time
0.4
0.50
0.6
ms
DATAALS_0
ALS Result when Dark
EAMBIENT = 0 Lux, 2k range
DATAALS_F
Full-Scale ALS ADC Code
EAMBIENT > selected range maximum Lux
ΔDATA1
DATA
Output Variation Over Light Sources:
Fluorescent, Incandescent and Sunlight
Ambient light sensing, no cover glass
After programmable active IR compensation
(Note 8)
±10
%
ΔDATA2
DATA
Output Variation Over Light Sources:
Fluorescent, Incandescent and Sunlight
Ambient light sensing under cover glass
After programmable active IR compensation
(Note 8)
±10
%
Linearity
ALS ADC Data Linearity
20% - 80% of full range
±5
%
DATAALS_0
Light Count, ALS_Range 125 Lux
E = 50 Lux (Note 9),
ALS_RANGE = 0
1555
1767
1979
Counts
DATAALS_1
Light Count, ALS_Range 250 Lux
E = 50 Lux (Note 9),
ALS_RANGE = 1
771
876
981
Counts
DATAALS_2
Light Count, ALS_Range 2000 Lux
E = 300 Lux (Note 9),
ALS_RANGE = 2
585
665
745
Counts
DATAALS_3
Light Count, ALS_Range 4000 Lux
E = 300 Lux (Note 9),
ALS_RANGE = 3
292
331
371
Counts
DATAPROX_0
Prox Data without Object in Path
DATAPROX_F
Full-Scale Prox ADC Code
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3
1
Counts
4095
1
Counts
Counts
255
Counts
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ISL29038
Electrical Specifications
PARAMETER
VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance. (Continued)
DESCRIPTION
ProxWASH
MIN
(Note 7)
TEST CONDITION
Washout Bit Activation Level
Norwood Solar Emulator
TYP
40k
ProxOffsetMax Maximum PROX Offset, Referenced to
Proximity ADC Range
ProxOffsetInc
MAX
(Note 7) UNITS
Lux
512
Proximity Offset Adjust Increment Referenced
to Proximity ADC Range
LSB
27
LSB
LED DRIVER (IRDR PIN)
tr
Rise Time for IRDR Sink Current
RLOAD = 15Ω at IRDR pin, 20% to 80%
25
ns
tf
Fall time for IRDR Sink Current
RLOAD = 15Ω at IRDR pin, 80% to 20%
15
ns
IIRDR_0
IRDR Sink Current
PROX_DR = 0; VIRDR = 0.5V
31.25
mA
IIRDR_1
IRDR Sink Current
PROX_DR = 1; VIRDR = 0.5V
62.5
mA
IIRDR_2
IRDR Sink Current
PROX_DR = 2; VIRDR = 0.5V
125
mA
IIRDR_3
IRDR Sink Current
PROX_DR = 3; VIRDR = 0.5V
250
mA
IRDR Leakage Current
PROX_EN = 0; VIRDR = 3.63V
0.001
VIRDR
IRDR Pin Voltage Compliance
Register bit PROX_DR = 0
tPULSE
IIRDR On Time Per PROX Reading
IIRDR_LEAK
0.50
1
µA
4.3
V
90
µs
0.52
V
MISCELLANEOUS
VREF
Voltage of REXT Pin
I2C Electrical Specifications
(Note 11).
SYMBOL
ALS_EN = 1 or PROX_EN = 1
For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1% tolerance
PARAMETER
TEST CONDITIONS
MIN
(Note 7)
TYP
MAX
(Note 7)
UNITS
VI2C
Supply Voltage Range for I2C Interface
3.63
V
fSCL
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
Input Leakage for each SDA, SCL Pin
1.25
V
0.05VDD
V
-10
0.4
V
10
µA
tSP
Pulse Width of Spikes that must be Suppressed by
the Input Filter
50
ns
tAA
SCL Falling Edge to SDA Output Data Valid
900
ns
10
pF
Ci
tHD:STA
Capacitance for each SDA and SCL Pin
Hold Time START Condition
After this period, the first clock
pulse is generated
600
ns
tLOW
LOW Period of the SCL Clock
Measured at the 30% of VDD
crossing
1300
ns
tHIGH
HIGH Period of the SCL Clock
600
ns
tSU:STA
Set-up Time for a START Condition
600
ns
tHD:DAT
Data Hold Time
30
ns
tSU:DAT
Data Set-up Time
100
ns
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ISL29038
I2C Electrical Specifications
(Note 11). (Continued)
SYMBOL
For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1% tolerance
PARAMETER
TEST CONDITIONS
MIN
(Note 7)
TYP
MAX
(Note 7)
UNITS
tR
Rise Time of both SDA and SCL Signals
(Note 12)
20 + 0.1xCb
ns
tF
Fall Time of both SDA and SCL Signals
(Note 12)
20 + 0.1xCb
ns
Set-up Time for STOP Condition
600
ns
Bus Free Time Between a STOP and START Condition
1300
ns
tSU:STO
tBUF
Cb
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
VnL
Noise Margin at the LOW Level
0.1VDD
V
VnH
Noise Margin at the HIGH Level
0.2VDD
V
Maximum determined by tR and tF
1
kΩ
NOTES:
7. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
8. Cover glass assumes fixed infrared/visible light transmissivity ratio of 10.
9. The LED light source irradiance is calibrated to produce the same ALS count as a fluorescent light source of the same Lux level.
10. An 850nm infrared LED is used in production test for proximity/IR sensitivity testing.
11. All parameters in I2C Electrical Specifications table are guaranteed by design and simulation.
12. Cb is the capacitance of the bus in pF.
FIGURE 4. I2C TIMING DIAGRAM
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ISL29038
Each I2C transaction ends with the master asserting a stop
condition (SDA rising while SCL remains high). For more
information about the I2C standard, consult the Philips™ I2C
specification documents.
ISL29038 Configuration and
Control
I2C Interface
Timing specifications are included in “I2C Electrical
Specifications” on page 4. The timing parameters are defined in
Figure 4.
ISL29038 configuration and control is performed using the I2C
or SMBus. The ISL29038’s I2C interface slave address is
internally hard wired as 8’b1000100x, where x denotes the R/W
bit.
The I2C interface on the ISL29038 supports single and multiple
byte read and write transfers using the random-read/write
protocol. The ISL29038 does not support I2C ‘Repeat Start’
protocol.
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 time after every transmitted byte.
NOTE: That in most system implementations, the ISL29038 is connected
to a single I2C master with one or more slave devices, consequently,
absence of ‘Repeat Start’ function does not adversely affect I2C bus
system performance.
Figure 5 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.
I2C DATA
DEVICE ADDRESS
START
I2C SDA
MASTER
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 (ISL29038)
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 ISL29038
A
A D7 D6 D5 D4 D3 D2 D1 D0
7
8
9
1
2
3
4
5
6
7
8
9
FIGURE 5. I2C DRIVER TIMING DIAGRAM FOR MASTER AND SLAVE CONNECTED TO COMMON BUS
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ISL29038
100
100
90
90
80
FULL-SCALE RANGE (%)
FULL-SCALE RANGE (%)
Typical Performance Curves
250mA
70
125mA
60
50
62.5mA
40
30
31.25mA
80
70
50
40
30
20
10
10
0
40
60
20
18% GREY CARD PROXIMITY DISTANCE (mm)
CIE 1924 PHOTOPIC CURVE
60
20
0
ALS RESPONSE (BLUE)
RANGE: 2k Lux
0
300
80
FIGURE 6. PROXIMITY SENSITIVITY (Note 13)
400
500
600
700
800
WAVELENGTH (nm)
900
1000
1100
FIGURE 7. ALS SENSITIVITY (Note 14)
100
15
NORMALIZED SENSITIVITY (%)
VALUE CHANGE (% FSR)
90
10
50%
5
10%
0
0
8k
16k
80
70
60
50
40
30
20
10
24k
32k
40k
0
-90
-60
FIGURE 8. PROXIMITY AMBIENT LIGHT REJECTION (Note 15)
-30
0
30
60
90
ANGLE (°)
AMBIENT LIGHT LEVEL (LUX)
FIGURE 9. ALS ANGULAR SENSITIVITY (Note 16)
NOTES:
13. The ISL29038 Proximity distance sweeps with different IRDR LED current settings using an 18% Grey card reflector.
14. The ISL29038 Ambient Light Sensor Spectral response when compared to a theoretical CIE 1924 Photopic curve. The ‘Blue’ line shows the ISL29038
response and the ‘Red’ line depicts the CIE 1924 Photopic curve.
15. The ISL29038 Proximity Ambient Light Rejection using a Norwood Solar Emulator. At 40k lux ambient light level, the Proximity Washout Count (Reg
0x0D[7:1]) is 127 indicating a saturation in Proximity Signal processing path. The Proximity Washout bit 0x0D[0] is active at approximately 90% of
the maximum level. At 10% initial PROX count (due to optical leakage from IR LED to the ISL29038), the PROX data error is under 2%. At 50% initial
PROX count (severe optical leakage), the PROX data error is about 7%.
16. The Ambient Light Sensor Angular Sensitivity of the ISL29038 using a white LED light source.
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ISL29038
ISL29038 Register Set
TABLE 1. CONFIGURATION AND CONTROL REGISTERS
ADDRESS
(HEX)
0x00
REGISTER NAME
Device ID
POWER-ON
DEFAULT
b11000xxx
REGISTER
ACCESS
RO
BIT
FIELDS
[7:0]
[7:3]
0x01
Config0
0x00
RW
RW
RW
RW
0x02
Config1
0x00
0x04
Config2
INTConfig
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0x00
0x10
8
FUNCTION
Device Identification
[11000]
ISL29038 Device ID
[2:0]
Reserved
[7:0]
Proximity Configuration
[7:6]
Reserved
[5]
[4:2]
[1:0]
RW
[7:0]
RW
[7]
PROX_EN
Proximity Enable/Disable
[1]
Enable
[0]
Disable
PROX_SLP
Proximity Sleep Time Select
[000]
400ms
[001]
100ms
[010]
50ms
[011]
25ms
[100]
12.5ms
[101]
6.25ms
[110]
3.125ms
[111]
0ms
IRDR_DRV
IR LED Current
[00]
31.25mA
[01]
62.5mA
[10]
125mA
[11]
250mA
Proximity/ALS Configuration
INT_ALG
Interrupt Algorithm
[1]
Window Comparator
[0]
Hysteresis Window
RW
[6:3]
PROX_OFFSET
Proximity Offset Compensation
RW
[2]
ALS_EN
Ambient Light Sensing Enable/Disable
[1]
Enable
[0]
Disable
RW
0x03
FUNCTION
NAME/VALUE
[1:0]
ALS_RANGE
Ambient Light Sensor Range Select
[00]
125 Lux
[01]
250 Lux
[10]
2000 Lux
[11]
4000 Lux
ALS_IR_COMP
Ambient Light Sensor IR Compensation
RW
[7:0]
RW
[7:5]
RW
[4:0]
ALSIRComp
ALS Infra Red Compensation
(Unsigned Binary)
RW
[7:0]
INTConfig
Interrupt Configuration, Status and Control
Reserved
FN7851.1
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ISL29038
TABLE 1. CONFIGURATION AND CONTROL REGISTERS (Continued)
ADDRESS
(HEX)
REGISTER NAME
POWER-ON
DEFAULT
REGISTER
ACCESS
RO
RW
RO
RO
RW
RW
BIT
FIELDS
[7]
[6:5]
[4]
[3]
[2:1]
[0]
FUNCTION
NAME/VALUE
PROX_INT_FLG
FUNCTION
Proximity Interrupt Flag
[1]
Proximity Interrupt Event
[0]
No Proximity Interrupt Event
PROX_PRST
Proximity Interrupt Reporting Persistency
[00]
INT after 1 Proximity Flag Event
[01]
INT after 2 Consecutive Proximity Flag Event
[10]
INT after 4 Consecutive Proximity Flag Event
[11]
INT after 8 Consecutive Proximity Flag Event
PWR_FAIL
Power Failure (Brown-out) Alarm
[1]
Brown-Out Detected
[0]
Normal Operation
ALS_INT_FLG
Ambient Light Sensor Interrupt Flag
[1]
ALS Interrupt Flag Event
[0]
No ALS Interrupt Flag Event
ALS_INT_PRST
ALS Interrupt Reporting Persistency
[00]
INT after 1 ALS Flag Event
[01]
INT after 2 Consecutive ALS Flag Event
[10]
INT after 4 Consecutive ALS Flag Event
[11]
INT after 8 Consecutive ALS Flag Event
INT_CFG
Interrupt Output (Pin) Configuration
[1]
Interrupt if ALS and PROX Event
[0]
Interrupt if ALS or PROX Event
0x05
PROX_INT_TL
0x00
RW
[7:0]
PROX_INT_TL
Proximity Interrupt LOW threshold
0x06
PROX_INT_TH
0xFF
RW
[7:0]
PROX_INT_TH
Proximity Interrupt HIGH threshold
0x07
ALS_INT_TL
0x00
RW
[7:0]
ALS_INT_TL1
ALS Interrupt LOW threshold bit[11:4]
0x08
ALS_INT_TLH
0x0F
RW
[7:0]
[7:4]
ALS_INT_TL0
ALS Interrupt LOW threshold bit[3:0]
[3:0]
ALS_INT_TH1
ALS Interrupt HIGH threshold bit[11:8]
[7:0]
ALS_INT_TH0
ALS Interrupt HIGH threshold bit[7:0]
0x09
ALS_INT_TH
0xFF
RW
ALS Interrupt LOW/HIGH threshold bits
0x0A
PROX_DATA
RO
[7:0]
PROX_DATA
Proximity Data (Unsigned Binary)
0x0B
ALS_DATA_HB
RO
[7:0]
ALS_DATA_HB
ALS Data HIGH Byte
[7:4]
Set to 0000
[3:0]
ALS Data Bit[11:8]
0x0C
ALS_DATA_LB
RO
[7:0]
ALS_DATA_LB
ALS Data Bit[7:0]
0x0D
PROX_AMBIR
RO
[7:0]
PROX_AMBIR
Proximity Mode Ambient IR Measurement
[7:1]
RO
0x0E
Config3
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0x00
9
[0]
[7:0]
Proximity Mode Ambient IR Component
PROX_WASH
Proximity Washout Status
[1]
Proximity Washout Detected
[0]
Normal Proximity Operation
SoftReset
Software Reset
0x38
Initiate Soft Reset
0x00
Normal operation
FN7851.1
January 23, 2015
ISL29038
Registers 0x01, 0x02 are used to configure the primary proximity
and ALS parameters. Register 0x03 is used for optimizing IR
compensation in ALS measurements. A procedure to optimize IR
compensation is described in “ALS IR Compensation” on page 11.
Register 0x04 is the Interrupt Configuration and Status Register,
and is used primarily to indicate interrupt events from proximity
and ALS measurements. A PWR_FAIL bit to indicate a
‘Brown-Out’ event is available and is set in case of a power supply
interruption. A ‘Brown-Out’ event does not generate a hardware
interrupt. The host micro-controller must clear this bit by writing a
‘0’ to Reg 0x04[4].
Register 0x04 is also used to configure ALS and Proximity
interrupt persistency and the operation of the INT pin.
The ALS runs continuously with new data available every 90ms.
The proximity sensor runs continuously with a time between
conversions controlled by PROX_SLP (Reg 0x01[6:4]).
Ambient Light Sensing
The ISL29038 is set for ambient light sensing when Register bit
ALS_EN = 1. Four measurement ranges from 125 Lux to 4000 Lux
are available. The ALS measurement range is configured via Reg
0x02[1:0].
Proximity Sensing
When proximity sensing is enabled (PROX_EN = 1), the external
IR LED is driven for 100µs by the built-in IR LED driver through
the IRDR pin.
Registers 0x05 and 0x06 are used to set the proximity ‘LOW’ and
‘HIGH’ threshold for proximity interrupt event generation.
Registers 0x07, 0x08 and 0x09 are used to set the ALS ‘LOW’
and ‘HIGH’ threshold. Two 12-bit numbers span three address
locations as shown in Table 1.
Data registers 0x0A holds result of proximity conversion. The
proximity result should be validated by ‘Washout’ bit in Reg
0x0D[0]. Registers 0x0B and 0x0C hold results of an ALS
measurement.
The ALS data is 12 bits wide. Least Significant Byte of the ALS
data is available at address 0x0C and Most Significant Byte
(MSB) of ALS data is available at address 0x0B. The MSB is right
justified, i.e., the upper nibble is always zero and lower nibble
contains four data bits.
Register 0x0D[7:1] contains ambient IR measurement in
proximity measurement phase. This measurement is for
detecting ambient Washout condition, which is indicated by Reg
0x0D[0] being ‘HIGH’. Proximity ‘Washout’ is described in
“Proximity Ambient Washout Detection” on page 11.
A software reset can be initiated by writing 0x38 to Reg 0x0E.
ISL29038 Operation
Photodiodes and ADCs
The ISL29038 contains two photodiode arrays, which convert
photons (light) into current. The ALS photodiodes are designed to
mimic the human eye’s wavelength response curve to visible light.
The ALS photodiodes’ current output is digitized by a 12-bit ADC.
The ALS ADC output is accessed by reading from Reg 0x0B and
0x0C when the ADC conversion is completed.
The ALS ADC converter uses a charge-balancing architecture.
Charge-balancing is best suited for converting small current signals
in the presence of periodic AC noise. The ISL29038 targets an
integration time of 90ms, which can vary ±15% from nominal. The
ALS integration time is intended to minimize 60Hz flicker.
The proximity sensor uses an 8-bit ADC, which operates in a
similar fashion. The IRDR pin drives (pulses) an infrared LED, the
emitted IR reflects off an object back into the ISL29038, and the
photo diodes convert the reflected IR to a current signal in
0.5ms. The ADC subtracts the IR reading before and after the
LED is driven to remove ambient IR contribution.
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10
ALS CONVERSION TIME = 90ms
SEVERAL  s BETWEEN
(FIXED)
CONVERSIONS
ALS
ACTIVE
90ms
PROX
SENSOR
ACTIVE
IRDR
(CURRENT
DRIVER)
90ms
90ms
90ms
90ms
TIME
0.50ms FOR PROX
CONVERSION
TIME
SERIES OF
CURRENT PULSES
TOTALING 0.09ms
TIME
SLEEP TIME
(PROX_SLP)
FIGURE 10. TIMING DIAGRAM FOR PROX/ALS EVENTS - NOT TO SCALE
The IR LED current depends on PROX_DRV (Reg 0x01[1:0]). Drive
current settings are as shown in Table 1. IR LED drive is in high
impedance state when not active.
When the IR from the LED reaches an object and gets reflected
back to the ISL29038, the reflected IR light is converted into a
current. This current is converted to digital data using an 8-bit
ADC. The proximity measurement takes 0.5ms for one
conversion including the 90μs LED drive time. The period
between proximity measurements is determined by PROX_SLP
(sleep time) in Reg 0x01[4:2].
Average LED driving current consumption is given by Equation 1.
I lRDR ;PEAK  90s
I lRDR ;AVE = ----------------------------------------------------T SLEEP
(EQ. 1)
A typical IRDR scheme is 250mA pulses every 400ms, averaging
about 56μA DC.
Total Current Consumption
Total current consumption is the sum of IDD and IIRDR. The IRDR
pin sinks current and the average IRDR current is calculated using
Equation 1. The IDD depends on voltage and the mode of
operation. For simplicity, Equation 1 ignores proximity ADC
conversion time since it is much smaller than the sleep time.
FN7851.1
January 23, 2015
ISL29038
ALS IR Compensation
Proximity Ambient Washout Detection
The ISL29038 is designed for operation under dark glass cover.
Glass or plastic covers can significantly attenuate visible light
and pass the Infrared light without much attenuation.
Consequently, the ISL29038 under a glass cover experiences an
IR rich environment.
Optical proximity sensor can saturate when illuminated with
excessive ambient light. The ISL29038 provides a warning flag
when the proximity measurement may be erroneous due to
excessive ambient light. The PROX_WASH register (Reg 0x0D[0])
reports this condition.
The on-chip ALS passive optical filter on the ISL29038 is designed
to block most of the IR incident on the ALS photo diodes. In
addition, the ISL29038 provides a programmable active IR
compensation that subtracts residual IR still reaching the sensor.
Interrupts Events
The ALS_IR_COMP register (Reg 0x03[4:0]) allows fine tuning of
the residual infrared component from the ALS output.
The recommended procedure for determining ALS IR
compensation is as follows:
• Illuminate the ISL29038 based product with a light source
without IR, such as a white LED. Record the ALS measurement
and the Lux level.
• Illuminate the device with an IR LED and the White LED. Take
an ALS measurement and Lux level measurement.
• Adjust the ALS_IR_COMP register (Reg 0x03, bits 4:0) to
compensate for the IR contribution.
• Repeat steps above until the IR light source contribution to the
ALS measurement is under 10 percent assuming no change in
Lux level due to IR light source.
Proximity Offset
Systems built with a protective glass cover over the ISL29038
can provide light ‘leakage’ or ‘crosstalk’ from the IR LED by
reflection from the glass saturating the proximity sensor
measurement system (Figure 11).
Saturation can occur when the reflection from the glass with no
object in the proximity detection space exceeds the full scale of
the measurement system. The ISL29038 proximity system
provides a user programmable proximity offset correction to
compensate for this reflection.
The ISL29038 interrupts are designed to minimize host
microcontroller overhead of continuous polling. The ISL29038
can generate interrupts on the results of an ALS measurement or
proximity measurement.
The ALS interrupt event ALS_FLAG (Reg 0x04[3]) is governed by
Reg 0x07 through 0x09. Two-12 bit high and low threshold
values are written to these registers. The ISL29038 will set the
ALS interrupt flag if the ADC conversion count in Registers 0x0B
and 0x0C are outside the programmed thresholds. The
ALS_FLAG is cleared by writing a ‘0’ to Reg 0x04[3].
A proximity interrupt event (PROX_FLAG) is governed by the high
and low thresholds in Reg 0x05 and 0x06 (PROX_LT and
PROX_HT) and is indicated by Reg 0x04[7]. PROX_FLAG is set
when the measured proximity data is more than the higher
threshold. The proximity interrupt flag is cleared when the
proximity data is lower than the low proximity threshold or by
writing a ‘0’ to Reg 0x04[7].
The Proximity interrupt generation can be selected between
‘out-of-window’ threshold and hysteresis schemes. When the
PROX_INT_ALG register (Reg 0x02, Bit 7) is set to 0, proximity
uses a window comparator scheme; when set to 1, proximity
uses a hysteresis scheme.
In hysteresis mode, the interrupt event is generated if the
proximity ADC count is higher than the PROX_HT threshold and
the interrupt event is cleared when the proximity ADC count is
less than the PROX_LT threshold. The interrupt event flag can
also be cleared by writing a ‘0’ to Reg 0x04[7].
INTERRUPT PERSISTENCE
To minimize interrupt events due to ‘transient’ conditions, an
interrupt persistency option is available for both ALS and proximity
measurements. Persistency requires ‘X-consecutive’ interrupt flags
before the INT pin is driven low. Both ALS and PROX have their own
independent interrupt persistency options. ALS_PRST and
PROX_PRST configuration are controlled from Reg 0x04.
GLASS COVER
Power-Up and ‘Brown-Out’ Reset
SENSOR
LED
PCB
FIGURE 11. PROXIMITY SET-UP HIGHLIGHTING CROSSTALK
REFLECTED FROM COVER GLASS
The PROX_IR_COMP register (Reg 0x02[6:3]) applies a corrective
offset to the received signal prior to ADC conversion, which
allows the signal to be brought within the usable range of the
proximity measurement system.
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11
The ISL29038 has an enhanced power-on-reset system. A
‘Brown-Out’ detector flag in Reg 0x04[4] informs the system that
the device has powered-up properly. This flag should be reset as
part of the initialization sequence.
A ‘Brown-Out’ condition is defined as an operating condition
when the power supply voltage is not within the specified limits.
During the brown-out period at power-up, the I2C interface and
the IR LED driver are inactive. Following brown-out, the I2C
interface is re-initialized and the configuration registers are set to
power-up default values. After power-up and during device
initialization, host should examine that the PWR_FAIL flag
FN7851.1
January 23, 2015
ISL29038
(Reg 0x04[4]) is set and then clear the flag by writing ‘0’ to Reg
0x04[4].
Typical Application Circuit
Following power-up, a ‘Brown-Out’ condition, if detected, is
reported by PWR_FAIL flag by Reg 0x04[4]. Device configuration
registers are not set to their power-up default after ‘Brown-Out’.
PWR_FAIL flag should be periodically monitored to detect post
power-up power supply interruption.
A typical application circuit for the ISL29038 is shown in
Figure 12. The ISL29038’s I2C address is internally hard wired as
‘1000100x’, with x representing the R/W bit. The device can be
connected to a system’s I2C bus together with other I2C
compliant devices. It is important to ensure that there is no
address conflict with other I2C devices on the bus.
Power-Down
Setting ALS_EN (Reg 0x02[2]) and PROX_EN (Reg 0x01[5]) to ‘0’
puts the ISL29038 into a power-down state with power supply
current dropping to less than 1µA. All configuration registers are
maintained in power-down mode.
Soft Reset
A software reset to ISL29038 can be initiated by writing 0x38 to
Reg 0x0E. Following reset, all configuration registers are set to
their default power-up state. After soft reset, the ISL29038
defaults to the power-down configuration.
ALS Data Count Read Out
A 2 byte I2C read from ALS_DATA_HB outputs MSB 1st data on
SDA. This data is LSB justified with a zero fill for unused bits.
NOTE: That the MSB byte address precedes the LSB byte address. The
ALS count is 256*(ALS_DATA_HB) + ALS_DATA_LB.
Proximity Detection of Various Objects
The SCL, SDA and INT pins on ISL29038 are open drain and
require pull-up resistors for proper system operation. Values of
the pull-up resistors is system dependent and can range from
2.2k to 10k depending upon the number of I2C devices on the
bus.
The proximity sensing system can be powered using a dual power
supply or using a single power supply. In dual supply
configuration, the IR LED and the ISL29038 are powered from
separate power supplies. The VDD IRLED can range from 2.25V to
5.0V and the VDD_ANALOG can range from 2.25V to 3.63V. In
dual supply configuration, resistor R2 should not be installed.
In single supply configuration, the IR LED and the ISL29038 are
powered from the same power source. The VDD_IRLED can range
from 2.25V to 3.63V and the VDD_Analog is derived from
VDD_IRLED using resistor R2.
In either power supply configuration, a 1µF decoupling capacitor
should be installed close to the AVDD pin, and another 1µF
decoupling capacitor should be placed close to the IR LED anode.
Proximity sensing relies on the amount of IR reflected back from
objects. A perfect black object would absorb all incident light and
reflect no photons. The ISL29038 is sensitive enough to detect
black ESD foam, which reflects only 1% of IR. Blonde hair typically
reflects more than brown hair and skin tissue is more reflective
than human hair.
IR penetrates into the skin and is reflected from within. As a
result, the proximity count generally peaks at contact and
monotonically decreases as skin moves away. The reflective
characteristics of skin are very different from that of a inanimate
object such as paper.
VDD_PULLUP
VDD_IRLED
R2
100
VDD_ANALOG
C2
1µF
C1
1µF
D1
IRLED
U1
8
1
GNDIR IRDR
7
2
AVDD
INT 6
3
AGND
SDA
5
4
RExt
SCL
SCL, SDA AND
INT PULL UPs
SMBus MASTER
INT
SDA
SCL
ISL29038
R1
499k
R1: 499k 1% RESISTOR
R2: 100Ω 5% RESISTOR
C1, C2: 1µF CERAMIC 10V CAPACITOR
D1: OSRAM SFH4650 INFRARED LED
FIGURE 12. TYPICAL APPLICATIONS CIRCUIT
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FN7851.1
January 23, 2015
ISL29038
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. A
standard reflow soldering profile with a +260°C maximum is
recommended. Additional information regarding soldering
ISL29038 is included in Intersil Technical Brief TB477.
Suggested PCB Footprint
Refer to TB477,“Surface Mount Assembly Guidelines for Optical
Dual FlatPack No Lead (ODFN) Package” before starting ODFN
product board mounting.
Additional information regarding soldering is also included in
Intersil Technical Brief TB477.
PCB Layout Considerations
The ISL29038 is relatively insensitive to PCB layout. Adherence
to the following guidelines will ensure first pass success and best
performance.
Route the I2C/SMBus SCL, SDA and the INT traces away from
sources of switching noise. A 499k 1% tolerance resistor must be
connected from the REXT pin to AGND. This node also needs to
be isolated from any switching noise.
ISL29038 pins IRGND and AGND should connect to a low
impedance ground with low resistance and low inductance
traces. Ferrite beads and inductors should be avoided in the
ground path. If necessary, due to RF consideration, the effects of
DCR (DC resistance) should be evaluated on ALS and Proximity
system performance.
A 1µF ceramic decoupling capacitor should be placed as close to
the AVDD pin as possible.
The ISL29038 drives the IR LED with 0.09ms current pulses. To
supply this pulsed current, a 1 to 10µF bulk decoupling capacitor
(C1) must be connected from the IR LED anode to the GNDIR pin
to minimize instantaneous resistive voltage drop. The connection
from IR LED cathode to the IRDR pin should be short and with
minimal inductance. Similarly, connection from the IR LED to
VDD must be made with a low impedance trace.
For most applications, a single power supply may be used to
power the IR LED and the ISL29038. Use of resistor R2 and
capacitor C2 (Figure 13) to help filter out the power supply noise
generated from IR LED switching is recommended for best
ISL29038 performance when using a single power supply. For
dual supply operation, resistor R2 should not be installed.
2.10
1
8
2
7
3
6
2.00
ALS SENSOR
OFFSET 0.03mm
ALS SENSOR AREA
0.66mm x 0.24mm
PROX SENSOR
OFFSET 0.42mm
4
5
PROX SENSOR AREA
0.57mm x 0.16mm
0.57
FIGURE 13. 8 LD ODFN SENSOR LOCATION OUTLINE - DIMENSIONS IN mm
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13
FN7851.1
January 23, 2015
ISL29038
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 revision.
DATE
REVISION
CHANGE
January 23, 2015
FN7851.1 Thermal Information table on page 3: changed theta JC value from 10 to 14.
Configuration and control registers on page 8; under Reg2 configure1 section: changed Window Comparator from
0 to 1 and Hysteresis Window from 1 to 0.
October 12, 2012
FN7851.0 Initial Release.
About Intersil
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14
FN7851.1
January 23, 2015
ISL29038
Package Outline Drawing
L8.2.1x2.0
8 LEAD OPTICAL DUAL FLAT NO-LEAD PLASTIC PACKAGE (ODFN)
Rev 3, 1/11
2.10
A
6
PIN 1
INDEX AREA
0.15
B
0.25
6
PIN 1
INDEX AREA
0.50
1.50
2.00
1.50
0.20±0.05 4
(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 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 indentifier may be
either a mold or mark feature.
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15
FN7851.1
January 23, 2015