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Low Power Ambient Light and Proximity Sensor with Intelligent Interrupt and Sleep Modes
ISL29028
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. 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 540s conversion time. The ISL29028 provides low power operation of ALS and proximity sensing with a typical 138A normal operation current (110A for sensors and internal circuitry, ~28A for external LED) with 220mA current pulses for a net 100s, 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 -40C to +85C ambient temperature range. It is packaged in a clear, lead-free 8 lead ODFN package.
ISL29028
Features
* Works Under All Light Sources Including Sunlight * Dual ADCs Measure ALS/Prox Concurrently * Intelligent Interrupt Scheme Simplifies C 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 100s 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 * 138A DC Typical Supply Current for ALS/Prox Sensing - 110A for Sensors and Internal Circuitry - 28A Typical Current for External IR LED (Assuming 220mA for 100s Every 800ms) * <1.0A 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
Pin Configuration
ISL29028 8 LD ODFN (2.0x2.1x0.7mm) TOP VIEW
ADDR0 VDD GND REXT 1 2 3 4 THERMAL PAD 8 7 6 5 IRDR INT SDA SCL
Applications*(see page 14)
* 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
*THERMAL PAD CAN BE CONNECTED TO GND OR ELECTRICALLY ISOLATED
March 2, 2010 FN6780.1
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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 (c) 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
Ordering Information
PART NUMBER (Notes 1, 2) ISL29028IROZ-T7 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. TEMP. RANGE (C) -40 to +85 PACKAGE TAPE AND REEL (Pb-free) 8 Ld ODFN PKG. DWG. # L8.2.1x2.0
Pin Descriptions
PIN NUMBER 0 1 2 3 4 5 6 7 8 PIN NAME T.PAD ADDR0 VDD GND REXT SCL SDA INT IRDR DESCRIPTION Thermal Pad (connect to GND or float) I2C address pin - pull high or low (do not float) Positive supply: 2.25V to 3.63V Ground External resistor (499k; 1%) connects this pin to ground I2C clock line I2C data line The I2C bus lines can be pulled from 1.7V to above VDD, 3.63V max
Interrupt pin; Logic output (open-drain) for interrupt 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 IR PHOTODIODE ARRAY IREF INTERRUPT FOSC IR DRIVER 4 REXT 3 GND 7 INT DUAL CHANNEL ADCs DATA REGISTER 1 I2C 5 6 ADDR0 SCL SDA
8
IRDR
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ISL29028
Absolute Maximum Ratings (TA = +25C)
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 Information
Thermal Resistance (Typical, Note 4) JA (C/W) 8 Ld ODFN. . . . . . . . . . . . . . . . . . . . . . . . . 88 Maximum Die Temperature . . . . . . . . . . . . . . . . . . . +90C Storage Temperature . . . . . . . . . . . . . . . . -40C to +100C Operating Temperature . . . . . . . . . . . . . . . -40C to +85C 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. 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. 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 SR_VDD IDD_OFF IDD_NORM Power Supply Range
VDD = 3.0V, TA = +25C, REXT = 499k 1% tolerance. CONDITION MIN TYP MAX UNIT 2.25 VDD Rising Edge between 0.4V and 2.25V ALS_EN = 0; PROX_EN = 0 ALS_EN = 1; PROX_EN = 1 ALS_EN = 0; PROX_EN = 1 ALS_EN = 1; PROX_EN = 0 0.5 0.1 110 80 96 5.25 88 100 0.54 EAMBIENT = 0 lux, 2k Range EAMBIENT > Selected Range Maximum Lux Ambient Light Sensing 10 1 112 0.8 125 3.0 3.63 V V/ms A A A A MHz ms ms Counts 4095 Counts %
DESCRIPTION
Input Power-up Slew Rate Supply Current when Powered Down Supply Current for ALS+Prox in Sleep Time
IDD_PRX_SLP Supply Current for Prox in Sleep Time IDD_ALS fOSC Supply Current for ALS Internal Oscillator Frequency
tINTGR_ALS 12-bit ALS Integration/Conversion Time tINTGR_PROX 8-bit Prox Integration/Conversion Time DATAALS_0 ALS Result when Dark DATAALS_F Full Scale ALS ADC Code DATA DATA Count Output Variation Over Three Light Sources: Fluorescent, Incandescent and Sunlight
DATAALS_1 Light Count Output with LSB of 0.0326 lux/count DATAALS_2 Light Count Output With LSB of 0.522 lux/count DATAPROX_0 Prox Measurement w/o Object in Path DATAPROX_F Full Scale Prox ADC Code DATAPROX_1 Prox Measurement Result tr tf IIRDR_0 IIRDR_1 Rise Time for IRDR Sink Current Fall time for IRDR Sink Current IRDR Sink Current IRDR Sink Current
E = 53 lux, Fluorescent (Note 6), ALS_RANGE = 0 E = 320 lux, Fluorescent (Note 6), ALS_RANGE = 1 460
1638 614 1
Counts 768 Counts Counts 255 Counts
(Note 7) RLOAD = 15 at IRDR pin, 20% to 80% RLOAD = 15 at IRDR pin, 80% to 20% PROX_DR = 0; VIRDR = 0.5V PROX_DR = 1; VIRDR = 0.5V PROX_EN = 0; VDD = 3.63V (Note 8)
36
46 500 500
56
Counts ns ns
95
110 220 0.001
125
mA mA
IIRDR_LEAK IRDR Leakage Current
1
A
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Electrical Specifications
PARAMETER VIRDR tPULSE VREF FI2C VI2C VIL VIH ISDA IINT PSRRIRDR NOTES: 6. A 550nm green LED is used in production test. The 550nm LED irradiance is calibrated to produce the same DATA count against a fluorescent light source of the same lux level. 7. 850nm infrared LED is used in production test for proximity/IR sensitivity testing. 8. Ability to guarantee IIRDR leakage of ~1nA is limited by test hardware. VDD = 3.0V, TA = +25C, REXT = 499k 1% tolerance. (Continued) CONDITION Register bit PROX_DR = 0 MIN TYP MAX UNIT 0.5 100 0.51 400 1.7 3.63 0.55 1.25 VOL = 0.4V VOL = 0.4V PROX_DR = 0; VIRDR = 0.5V to 4.3V 3 3 5 5 4 4.3 V s V kHz V V V mA mA mA/V
DESCRIPTION Acceptable Voltage Range on IRDR Pin Net IIRDR On Time Per PROX Reading Voltage of REXT Pin I2C Clock Rate Range Supply Voltage Range for I2C Interface SCL and SDA Input Low Voltage SCL and SDA Input High Voltage SDA Current Sinking Capability INT Current Sinking Capability (IIRDR)/(VIRDR)
I2C Electrical Specifications For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25C, REXT = 499k 1%
tolerance (Note 9). PARAMETER VI2C fSCL VIL VIH Vhys VOL Ii tSP tAA Ci tHD:STA tLOW tHIGH tSU:STA tHD:DAT tSU:DAT tR tF tSU:STO DESCRIPTION Supply Voltage Range for SCL Clock Frequency SCL and SDA Input Low Voltage SCL and SDA Input High Voltage Hysteresis of Schmitt Trigger Input Low-level output voltage (open-drain) at 4mA sink current Input Leakage for each SDA, SCL pin Pulse width of spikes that must be suppressed by the input filter SCL Falling Edge to SDA Output Data Valid Capacitance for each SDA and SCL pin Hold Time (Repeated) START Condition LOW Period of the SCL clock HIGH period of the SCL Clock Set-up Time for a Repeated START Condition Data Hold Time Data Set-up Time Rise Time of both SDA and SCL Signals Fall Time of both SDA and SCL Signals Set-up Time for STOP Condition (Note 10) (Note 10) After this period, the first clock pulse is generated Measured at the 30% of VDD crossing 600 1300 600 600 30 100 20 + 0.1xCb 20 + 0.1xCb 600 -10 1.25 0.05VDD 0.4 10 50 900 10 I2C Interface CONDITION MIN 1.7 TYP MAX UNIT 3.63 400 0.55 V kHz V V V V A ns ns pF ns ns ns ns ns ns ns ns ns
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I2C Electrical Specifications For SCL and SDA unless otherwise noted, VDD = 3V, TA = +25C, REXT = 499k 1%
tolerance (Note 9). (Continued) PARAMETER tBUF Cb Rpull-up tVD;DAT tVD:ACK VnL VnH NOTES: 9. All parameters in I2C Electrical Specifications table are guaranteed by design and simulation. 10. Cb is the capacitance of the bus in pF. DESCRIPTION Bus Free Time Between a STOP and START Condition Capacitive Load for Each Bus Line SDA and SCL system bus pull-up resistor Data Valid Time Data Valid Acknowledge Time Noise Margin at the LOW Level Noise Margin at the HIGH Level 0.1VDD 0.2VDD Maximum is determined by tR and tF 1 0.9 0.9 CONDITION MIN 1300 400 TYP MAX UNIT ns pF k s s V V
FIGURE 1. I2C TIMING DIAGRAM
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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
0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0E 0x0F (n/a) CONFIGURE INTERRUPT PROX_LT PROX_HT ALSIR_TH1 ALSIR_TH2 ALSIR_TH3 PROX_DATA ALSIR_DT1 ALSIR_DT2 TEST1 TEST2 (Unused) (Write as 0x00) (Write as 0x00) ALSIR_HT[3:0] ALSIR_HT[11:4] PROX_DATA[7:0] ALSIR_DATA[7:0] ALSIR_DATA[11:8] PROX EN PROX_FLAG PROX_SLP[2:0] PROX_PRST[1:0] (Write 0)
7
6
5
4
(Reserved)
3
2
1
0
DEFAULT
(n/a)
PROX_DR ALS_FLAG
ALS_EN
ALS_RANGE ALSIR_MODE INT_CTRL
0x00 0x00 0x00 0xFF 0x00
ALS_PRST[1:0]
PROX_LT[7:0] PROX_HT[7:0] ALSIR_LT[7:0] ALSIR_LT[11:8]
0xF0 0xFF 0x00 0x00 0x00 0x00 0x00
Register Descriptions
TABLE 2. REGISTER 0x00 (RESERVED) BIT # 7:0 ACCESS RO DEFAULT (n/a) NAME (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 PROX_EN (Prox Enable) FUNCTION/OPERATION 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 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 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
6:4
RW
0x00
PROX_SLP (Prox Sleep)
3 2 1 0
RW RW RW RW
0x00 0x00 0x00 0x00
PROX_DR (Prox Drive) ALS_EN (ALS Enable) ALS_RANGE (ALS Range)
When = 0, IRDR behaves as a pulsed 110mA current sink When = 1, IRDR behaves as a pulsed 220mA current sink When = 0, ALS/IR sensing is disabled When = 1, continuous ALS/IR sensing is enabled with new data ready every 100ms When = 0, ALS is in low-lux range When = 1, ALS is in high-lux range
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
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TABLE 4. REGISTER 0x02 (INTERRUPT) - PROX/ALS INTERRUPT CONTROL BIT # 7 ACCESS DEFAULT FLAG 0x00 BIT NAME PROX_FLAG (Prox Flag) PROX_PRST (Prox Persist) Unused (Write 0) ALS_FLAG (ALS FLAG) ALS_PRST (ALS Persist) INT_CTRL (Interrupt Control) FUNCTION/OPERATION 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 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)
6:5
RW
0x00
4 3
RW FLAG
0x00 0x00
2:1
RW
0x00
0
RW
0x00
TABLE 5. REGISTER 0x03 (PROX_LT) - INTERRUPT LOW THRESHOLD FOR PROXIMITY SENSOR BIT # 7:0 ACCESS RW DEFAULT 0x00 BIT NAME PROX_LT (Prox Threshold) FUNCTION/OPERATION 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 0xFF BIT NAME PROX_HT (Prox Threshold) FUNCTION/OPERATION 8-bit interrupt high threshold for proximity sensing
TABLE 7. REGISTER 0x05 (ALSIR_TH1) - INTERRUPT LOW THRESHOLD FOR ALS/IR BIT # 7:0 ACCESS RW DEFAULT 0x00 BIT NAME 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 # 7:4 3:0 ACCESS RW RW DEFAULT 0x0F 0x00 BIT NAME FUNCTION/OPERATION
ALSIR_HT[3:0] Lower 4 bits (of 12 bits) for ALS/IR high interrupt threshold (ALS/IR High Thr.) 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 # 7:0 ACCESS RW DEFAULT 0xFF BIT NAME ALSIR_HT[11:4] (ALS/IR High Thr.) FUNCTION/OPERATION Upper 8 bits (of 12 bits) for ALS/IR high interrupt threshold
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TABLE 10. REGISTER 0x08 (PROX_DATA) - PROXIMITY SENSOR DATA BIT # 7:0 ACCESS RO DEFAULT 0x00 BIT NAME PROX_DATA (Proximity Data) FUNCTION/OPERATION Results of 8-bit proximity sensor ADC conversion
TABLE 11. REGISTER 0x09 (ALSIR_DT1) - ALS/IR SENSOR DATA (LOWER 8 BITS) BIT # 7:0 ACCESS RO DEFAULT 0x00 BIT NAME ALSIR_DATA (ALS/IR Data) FUNCTION/OPERATION 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 # 7:4 3:0 ACCESS RO RO DEFAULT 0x00 0x00 BIT NAME (Unused) ALSIR_DATA (ALS/IR Data) Unused bits. Upper 4 bits (of 12 bits) from result of ALS/IR sensor conversion FUNCTION/OPERATION
TABLE 13. REGISTER 0x0E (TEST1) - TEST MODE BIT # 7:0 ACCESS RO DEFAULT 0x00 BIT NAME (Write as 0x00) FUNCTION/OPERATION Test mode register. When 0x00, in normal operation.
TABLE 14. REGISTER 0x0F (TEST2) - TEST MODE 2 BIT # 7:0 ACCESS RO DEFAULT 0x00 BIT NAME (Write as 0x00) FUNCTION/OPERATION Test mode register. When 0x00, in normal operation.
I2C DATA I2C SDA MASTER
START
DEVICE ADDRESS
WA
REGISTER ADDRESS
STOP START
DEVICE ADDRESS
A
DATA BYTE0
A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A
A6 A5 A4 A3 A2 A1 A0 W
A
SDA DRIVEN BY ISL29028
I2C SDA SLAVE (ISL29028)
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A D7 D6 D5 D4 D3 D2 D1 D0
I2C CLK
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
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, 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).
For more information about the I2C standard, please consult the PhilipsTM 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.
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ISL29028
ALS CONVERSION TIME = 100ms (FIXED) ALS ACTIVE 100ms 100ms 100ms 100ms 100ms TIME SEVERAL s BETWEEN CONVERSIONS
PROX SENSOR ACTIVE
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]).
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
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.
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 x 100s I lRDR ;AVE = ------------------------------------------------------T SLEEP (EQ. 1)
A typical IRDR scheme is 220mA amplitude pulses every 800ms, which yields 28A 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.
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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
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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. In Equation 2, Ecalc is the calculated lux reading and OUT represents the ADC code. The constant 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 0 1 RANGE (Lux/Count) 0.0326 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.
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 0x00 to three registers: 0x0E, 0x0F, and 0x01 (in that order), 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.
Typical Circuit
A typical application for the ISL29028 is shown in Figure 5. The ISL29028's I2C address is internally hardwired as 0b100010, 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.
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.
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 +260C. A standard reflow soldering profile with a +260C maximum is recommended. (http://www.intersil.com/data/tb/TB477.pdf)
Calculating Lux
The ISL29028's ADC output codes are directly proportional to lux when in ALS mode (see ALSIR_MODE bit).
E calc = RANGE x OUT ADC (EQ. 2)
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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
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 0.1F and 1F power supply decoupling capacitors need to be placed close to the device.
VI2C_PULL-UP R1 10k R2 10k R3 10k I2C MASTER MICROCONTROLLER INT SDA SCL
VDD VIR-LED
SLAVE_0 1 2 C1 1F C2 0.1F 3 4 ADDR0 IRDR VDD GND REXT INT SDA SCL 8 7 6 5
SLAVE_1 SDA SCL
I2C SLAVE_n SDA SCL
REXT ISL29028 499k
FIGURE 5. ISL29028 TYPICAL CIRCUIT
Typical Performance Curves
1.0 0.9 NORMALIZED INTENSITY 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 350 550 750 950 SUN HALOGEN FLUORESCENT
VDD = 3.0V, REXT = 499k
1.0 0.9 NORMALIZED RESPONSE 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 300 400 500 600 700 800 900 1000 1100 ALS
HUMAN EYE IR/PROX
INCAND.
WAVELENGTH (nm)
WAVELENGTH (nm)
FIGURE 6. SPECTRUM OF FOUR LIGHT SOURCES NORMALIZED BY LUMINOUS INTENSITY (LUX)
FIGURE 7. ISL29028 SENSITIVITY TO DIFFERENT WAVELENGTHS
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Typical Performance Curves
1.0 0.9 NORMALIZED SENSITIVITY
VDD = 3.0V, REXT = 499k (Continued)
2500 LUX METER READING (LX) HALOGEN 2000
0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -90
1500 FLUORESCENT 1000 INCANDESCENT
500
0 -60 -30 0 30 60 90 ANGULAR OFFSET ()
0
1000
2000
3000
4000
5000
ALS CODE (12-BIT)
FIGURE 8. ANGULAR SENSITIVITY
FIGURE 9. ALS LINEARITY OVER 3 LIGHT SOURCES (2000 LUX RANGE)
300 250 PROX COUNTS (8-BIT) 200 150 100 50 0 110mA MODE 18% GREY CARD
160 ALS+PROX (DURING PROX SLEEP) 140 MEASURED IDD (A) 220mA MODE ALS-ONLY 120 100 80 60 40 2.25 PROX (DURING PROX SLEEP)
WHITE COPY PAPER
0
20
40
60
80 100 120 DISTANCE (mm)
140
160
180
200
2.40
2.55
2.70
2.85 3.00 3.15 INPUT VDD (V)
3.30
3.45 3.60
FIGURE 10. PROX COUNTS vs DISTANCE WITH 10CM x 10CM REFLECTOR (USING ISL29028 EVALUATION BOARD)
FIGURE 11. VDD vs IDD FOR VARIOUS MODES OF OPERATION
CHANGE FROM +25C MEASUREMENT (%)
240 220mA-MODE (PROX_DR = 1) 220 200 IIRDR (A) 180 160 140 120 100 0 0.5 1.0 1.5 2.0 110mA-MODE (PROX_DR = 0) 2.5 3.0 3.5 4.0 4.5 5.0
10 8 6 4 2 0 -2 -4 -6 -8 -10 -40 -20 0 20 40 60 80
VIRDR (V)
TEMPERATURE (C)
FIGURE 12. IRDR PULSE AMPLITUDE vs VIRDR
FIGURE 13. STABILITY OF ALS COUNT OVER TEMP (AT 300 LUX INCANDESCENT)
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Typical Performance Curves
10 9 8 ALS CODE (12-BIT) 7 6 5 4 3 2 1 0 -40
VDD = 3.0V, REXT = 499k (Continued)
10 TEMPERATURE (C)
60
FIGURE 14. STABILITY OF ALS COUNT OVER-TEMPERATURE (AT 0.00 LUX)
2.10
1
8
2
7
SENSOR OFFSET
2.00
0.43
3
6 0.50
4
5
0.42
FIGURE 15. 8 LD ODFN SENSOR LOCATION OUTLINE - DIMENSIONS IN mm
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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 3/2/10 REVISION FN6780.0 Initial release. CHANGE
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 infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com 14
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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 2.00 1.50 0.50 PIN 1 INDEX AREA
1.50 0.200.05
(2X)
0.10 8X 0 . 35 0 . 05 0.75
0.10 M C A B
TOP VIEW
BOTTOM VIEW
SEE DETAIL "X" 2.50 0.10 C 2.10 0.700.05 BASE PLANE SIDE VIEW (6x0.50) SEATING PLANE 0.08 C C
(1.50)
(8x0.20) (8x0.20) (8x0.55) (0.75) TYPICAL RECOMMENDED LAND PATTERN NOTES: 1.
C
0 . 2 REF
5
0 . 00 MIN. 0 . 05 MAX. DETAIL "X"
Dimensions are in millimeters. Dimensions in ( ) for Reference Only. Dimensioning and tolerancing conform to ASME Y14.5m-1994. Unless otherwise specified, tolerance : Decimal 0.05 Dimension b applies to the metallized terminal and is measured between 0.25mm and 0.35mm from the terminal tip.
2. 3. 4.
5. 6.
Tiebar shown (if present) is a non-functional feature. 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.
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