Intersil ISL29028A Low power ambient light and proximity sensor with intelligent interrupt Datasheet

Low Power Ambient Light and Proximity Sensor with
Intelligent Interrupt and Sleep Modes
ISL29028A
Features
The ISL29028A is an integrated ambient and infrared light-todigital 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
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 ISL29028A 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 ISL29028A 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 ISL29028A 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.
Applications
• 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
February 8, 2011
FN7721.1
1
• Dual ADCs Measure ALS/Prox Concurrently
• Intelligent Interrupt Scheme Simplifies μC Code
• 0.5% Typical Nonlinearity
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
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2010, 2011. 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.
ISL29028A
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
4
3
REXT
GND
Pin Configuration
ISL29028A
8 LD ODFN (2.0mmX2.1mmX0.7mm)
TOP VIEW
ADDR0
1
VDD
2
GND
3
REXT
4
THERMAL
PAD
Pin Descriptions
PIN
NUMBER
PIN
NAME
0
T.PAD
1
ADDR0
I2C address pin - pull high or low
(do not float)
DESCRIPTION
Thermal Pad (connect to GND or float)
8
IRDR
7
INT
6
SDA
2
VDD
Positive supply: 2.25V to 3.63V
5
SCL
3
GND
Ground
4
REXT
External resistor (499kΩ; 1%) connects this
pin to ground
5
SCL
6
SDA
I2C clock line The I2C bus lines can be pulled
from 1.7V to above VDD, 3.63V
I2C data line
max
7
INT
8
IRDR
*THERMAL PAD CAN BE CONNECTED TO GND OR
ELECTRICALLY ISOLATED
Interrupt pin; Logic output
(open-drain) for interrupt
IR LED driver pin - current flows into
ISL29028A from LED cathode
Ordering Information
PART NUMBER
(Notes 1, 2, 3)
ISL29028AIROZ-T7
TEMP. RANGE
(°C)
-40 to +85
PACKAGE
Tape & Reel
(Pb-free)
8 Ld ODFN
PKG.
DWG. #
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 ISL29028A. For more information on MSL, please see Technical Brief
TB363.
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ISL29028A
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 6). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Thermal Resistance (Typical)
θJA (°C/W) θJC (°C/W)
8 Ld ODFN Package (Notes 4, 5) . . . . . . . .
88
10
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. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside.
6. 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
tINTGR_PROX
8-bit Prox Integration/Conversion Time
Linearity ALS_1 Nonlinearity
88
V/ms
100
112
0.54
EAMBIENT = 0, 53, 90 Lux; ALS_RANGE = 0
(Note 7)
-6
ms
ms
0.5
+6
%
1
3
Counts
4095
Counts
DATAALS_0
ALS Result when Dark
EAMBIENT = 0 lux, 2k Range
DATAALS_F
Full Scale ALS ADC Code
EAMBIENT > Selected Range Maximum Lux
(Note 11)
ΔDATA
DATA
Count Output Variation Over Three Light Sources:
Fluorescent, Incandescent and Sunlight
Ambient Light Sensing
±10
%
DATAALS_1
Light Count Output with LSB of 0.0326 Lux/Count
E = 53 lux, Fluorescent (Notes 8, 11),
ALS_RANGE = 0
1638
Counts
DATAALS_2
Light Count Output With LSB of 0.522 Lux/Count
E = 320 lux, Fluorescent (Note 8),
ALS_RANGE = 1
460
614
768
Counts
1
2
Counts
255
Counts
56
Counts
DATAPROX_0
Prox Measurement w/o Object in Path
DATAPROX_F
Full Scale Prox ADC Code
DATAPROX_1
Prox Measurement Result
(Note 9)
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
3
36
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ISL29028A
Electrical Specifications
PARAMETER
VDD = 3.0V, TA = +25°C, REXT = 499kΩ 1% tolerance. (Continued)
DESCRIPTION
CONDITION
MIN
TYP
MAX
UNIT
95
110
125
mA
IIRDR_0
IRDR Sink Current
PROX_DR = 0; VIRDR = 0.5V
IIRDR_1
IRDR Sink Current
PROX_DR = 1; VIRDR = 0.5V
IRDR Leakage Current
PROX_EN = 0; VDD = 3.63V (Note 10)
VIRDR
Acceptable Voltage Range on IRDR Pin
Register bit PROX_DR = 0
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
IIRDR_LEAK
220
0.001
0.5
1.7
mA
1
µA
4.3
V
400
kHz
3.63
V
0.55
V
VIL
SCL and SDA Input Low Voltage
VIH
SCL and SDA Input High Voltage
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
1.25
V
NOTES:
7. Nonlinearity is defined as: [(Measured Counts at 53 lux)-(Expected Counts at 53 lux)]/4095. Expected counts are calculated using an endpoint linearfit trendline from measurements at 0 lux and 90 lux.
8. 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
9. An 850nm infrared LED is used to test PROX/IR sensitivity in an internal test mode.
10. Ability to guarantee IIRDR leakage of ~1nA is limited by test hardware.
11. For ALS applications under light-distorting glass, please see the section titled ALS Range 1 Considerations.
I2C Electrical Specifications
(Note 12).
PARAMETER
For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1% tolerance
DESCRIPTION
CONDITION
MIN
TYP
MAX
UNIT
3.63
V
VI2C
Supply Voltage Range for I2C Interface
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
Ci
Capacitance for each SDA and SCL pin
10
pF
tHD:STA
Hold Time (Repeated) 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 Repeated START Condition
600
ns
tHD:DAT
Data Hold Time
30
ns
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ISL29028A
I2C Electrical Specifications
(Note 12). (Continued)
PARAMETER
tSU:DAT
For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25°C, REXT = 499kΩ 1% tolerance
DESCRIPTION
CONDITION
Data Set-up Time
MIN
TYP
MAX
UNIT
100
ns
tR
Rise Time of both SDA and SCL Signals
(Note 13)
20 + 0.1xCb
ns
tF
Fall Time of both SDA and SCL Signals
(Note 13)
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
Maximum is determined by tR and tF
1
pF
Rpull-up
SDA and SCL System Bus Pull-up Resistor
kΩ
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
NOTES:
12. All parameters in I2C Electrical Specifications table are guaranteed by design and simulation.
13. Cb is the capacitance of the bus in pF.
FIGURE 1. I2C TIMING DIAGRAM
5
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ISL29028A
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. ISL29028A REGISTERS AND REGISTER BITS
BIT
ADDR
REG NAME
7
6
5
4
3
2
1
0
DEFAULT
PROX_DR
ALS_EN
ALS_RANGE
ALSIR_MODE
0x00
INT_CTRL
0x00
0x00
(n/a)
0x01
CONFIGURE
PROX EN
(Reserved)
0x02
INTERRUPT
PROX_FLAG
0x03
PROX_LT
PROX_LT[7:0]
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
PROX_SLP[2:0]
PROX_PRST[1:0]
(Write 0)
(n/a)
ALS_FLAG
ALS_PRST[1:0]
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
RW
DEFAULT
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 pulses is 0.0ms (run continuously)
110; sleep time between prox IR LED pulses is 12.5ms
101; sleep time between prox IR LED pulses is 50ms
100; sleep time between prox IR LED pulses is 75ms
011; sleep time between prox IR LED pulses is 100ms
010; sleep time between prox IR LED pulses is 200ms
001; sleep time between prox IR LED pulses is 400ms
000; sleep time between prox IR LED pulses is 800ms
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
ALSIR_MODE
(ALSIR Mode)
When = 0, ALS/IR data register contains visible ALS sensing data
When = 1, ALS/IR data register contains IR spectrum sensing data
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ISL29028A
TABLE 4. REGISTER 0x02 (INTERRUPT) - PROX/ALS INTERRUPT CONTROL
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7
FLAG
0x00
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”
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
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
0
RW
0x00
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”
ALS_PRST
(ALS Persist)
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
INT_CTRL
When = 0, set INT pin low if PROX_FLAG or ALS_FLAG high (logical OR)
(Interrupt Control) 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
7:0
DEFAULT
BIT NAME
0x00
PROX_LT
(Prox Threshold)
RW
FUNCTION/OPERATION
8-bit interrupt low threshold for
proximity sensing
TABLE 6. REGISTER 0x04 (PROX_HT) - INTERRUPT HIGH THRESHOLD FOR PROXIMITY SENSOR
BIT #
ACCESS
DEFAULT
BIT NAME
FUNCTION/OPERATION
7:0
RW
0xFF
PROX_HT
(Prox Threshold)
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
Lower 4 bits (of 12 bits) for ALS/IR high interrupt threshold
Upper 4 bits (of 12 bits) for ALS/IR low interrupt threshold
7:4
RW
0x0F
ALSIR_HT[3:0]
(ALS/IR High Thr.)
3:0
RW
0x00
ALSIR_LT[11:8]
(ALS/IR Low Thr.)
FUNCTION/OPERATION
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.)
FUNCTION/OPERATION
Upper 8 bits (of 12 bits) for ALS/IR high interrupt threshold
TABLE 10. REGISTER 0x08 (PROX_DATA) - PROXIMITY SENSOR DATA
BIT #
ACCESS
DEFAULT
BIT NAME
7:0
RO
0x00
PROX_DATA
(Proximity Data)
7
FUNCTION/OPERATION
Results of 8-bit proximity sensor ADC conversion
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ISL29028A
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
Test mode register. When 0x00, in normal operation
REGISTER ADDRESS
W A
A
SDA DRIVEN BY MASTER
1
2
3
4
5
6
7
8
9
A
SDA DRIVEN BY MASTER
1
2
3
4
5
6
DEVICE ADDRESS
STOP START
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
I2C SDA
SLAVE (ISL29028A)
I2C CLK
FUNCTION/OPERATION
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 ISL29028A
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 ISL29028A’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.
Photodiodes and ADCs
The ISL29028A 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.
Each I2C transaction ends with the master asserting a stop
condition (SDA rising while SCL remains high).
For more information about the I2C standard, please consult the
Philips™ I2C specification documents.
8
FN7721.1
February 8, 2011
ISL29028A
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 ISL29028A, 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 ISL29028A 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 ISL29028A 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 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.
9
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 ISL29028A, 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. IDD depends on
voltage and the mode-of-operation as seen in Figure 11.
Interrupt Function
The ISL29028A 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”.
FN7721.1
February 8, 2011
ISL29028A
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 ISL29028A 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-arow 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.
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.
ALS Range 1 Considerations
Proximity Detection of Various Objects
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.
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 ISL29028A 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.
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 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 ISL29028A 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 ISL29028A’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
10
FN7721.1
February 8, 2011
ISL29028A
Typical Circuit
A typical application for the ISL29028A is shown in Figure 5. The
ISL29028A’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.
Suggested PCB Footprint
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.
(http://www.intersil.com/data/tb/TB477.pdf)
Layout Considerations
Soldering Considerations
Convection heating is recommended for reflow soldering; directinfrared 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.
The ISL29028A 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.
ALS Sensor Window Layout
Special care should be taken to ensure that the sensor, as
outlined in the sensor location outline, is uniformly illuminated.
Shadows that result from off angle window openings that affect
that uniform illumination can affect the measurement results.
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
REXT
499kΩ
SLAVE_1
8
7
I2C SLAVE_n
SDA
SDA
SCL
SCL
6
5
ISL29028A
FIGURE 5. ISL29028A TYPICAL CIRCUIT
11
FN7721.1
February 8, 2011
ISL29028A
Typical Performance Curves
VDD = 3.0V, REXT = 499kΩ
1.0
1.0
FLUORESCENT
0.8
0.7
0.6
HALOGEN
0.5
INCAND.
SUN
0.4
HUMAN EYE
0.9
NORMALIZED RESPONSE
NORMALIZED INTENSITY
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
700
800
900
1000
1100
FIGURE 7. ISL29028A SENSITIVITY TO DIFFERENT
WAVELENGTHS
FIGURE 6. SPECTRUM OF FOUR LIGHT SOURCES NORMALIZED
BY LUMINOUS INTENSITY (LUX)
2500
1.0
0.9
HALOGEN
LUX METER READING (LX)
NORMALIZED SENSITIVITY
600
WAVELENGTH (nm)
WAVELENGTH (nm)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
2000
1500
FLUORESCENT
1000
INCANDESCENT
500
0.1
0
-90
-60
-30
0
30
60
0
90
0
1000
2000
ANGULAR OFFSET (°)
FIGURE 8. ANGULAR SENSITIVITY
5000
160
ALS+PROX (DURING PROX SLEEP)
18% GREY CARD
140
MEASURED IDD (µA)
250
PROX COUNTS (8-BIT)
4000
FIGURE 9. ALS LINEARITY OVER 3 LIGHT SOURCES (2000 LUX
RANGE)
300
220mA MODE
200
110mA MODE
150
100
WHITE COPY PAPER
ALS-ONLY
120
100
80
PROX (DURING PROX SLEEP)
60
50
0
3000
ALS CODE (12-BIT)
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
3.30
3.45 3.60
INPUT VDD (V)
FIGURE 11. VDD vs IDD FOR VARIOUS MODES OF OPERATION
FN7721.1
February 8, 2011
ISL29028A
Typical Performance Curves
VDD = 3.0V, REXT = 499kΩ (Continued)
50
240
220mA-MODE (PROX_DR = 1)
ALS COUNT CHANGE FROM
+25°C MEASUREMENT (%)
40
200
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
5.0
30
20
10
0
-10
-20
-30
-40
-50
-40
-15
VIRDR (V)
10
35
TEMPERATURE (°C)
60
85
FIGURE 13. STABILITY OF ALS COUNT OVER TEMP (AT 300 LUX)
FIGURE 12. IRDR PULSE AMPLITUDE vs VIRDR
10
9
8
ALS CODE (12-BIT)
IIRDR (mA)
220
7
6
5
4
3
2
1
0
-40
10
60
TEMPERATURE (°C)
FIGURE 14. STABILITY OF ALS COUNT OVER TEMP (AT 0.00 LUX)
13
FN7721.1
February 8, 2011
ISL29028A
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
FN7721.1
February 8, 2011
ISL29028A
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
2/1/2011
FN7721.1
CHANGE
Changed DATAALS_2 Min/Max on page 3 from 503/725 Counts Counts to 460/768 Counts
Added “ALS Sensor Window Layout” on page 11
Updated “Package Outline Drawing” on page 16. Changes as follows:
In the “bottom view” image, added a dimension from the edge of the package to the edge of the first lead, which
is 0.15mm. Also added a dimension from the edge of the package (top edge in the picture) to the center of the
lead, which is 0.25mm
11/18/2010
FN7721.0
Initial Release.
Products
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The Company's products
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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: ISL29028A
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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
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For information regarding Intersil Corporation and its products, see www.intersil.com
15
FN7721.1
February 8, 2011
ISL29028A
Package Outline Drawing
L8.2.1x2.0
8 LEAD OPTICAL DUAL FLAT NO-LEAD PLASTIC PACKAGE (ODFN)
Rev 2, 12/10
2.10
A
0.15
B
0.25
6
PIN 1
INDEX AREA
6
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 indentifier may be
either a mold or mark feature.
16
FN7721.1
February 8, 2011