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ISL29015
Data Sheet October 31, 2008 FN6522.0
Integrated Digital Ambient Light Sensor and Proximity Sensor
The ISL29015 is an integrated ambient and infrared light to digital converter with a built-in IR LED driver and I2C/SMBus interface. This device provides not only ambient light sensing to allow robust backlight/display brightness control but also infrared sensing to allow proximity estimation. For ambient light sensing, an internal 16-bit ADC has been designed based on the charge-balancing A/D conversion technique. The ADC conversion time is nominally 100ms and is user adjustable from 25s to 100ms depends on oscillator frequency and ADC resolution. This ADC is capable of rejecting 50Hz and 60Hz flicker noise caused by artificial light sources. The lux-range-select feature allows users to program the lux range for optimized counts/lux. For proximity sensing, the ADC is used to digitize the output signal from the photodiode array when the internal IR LED driver is turned on and off for the programmed time periods under user-selected modulation frequency to drive the external IR LED. As this proximity sensor employs a noise cancellation scheme to highly reject unwanted IR noise, the digital output of proximity sensing decreases with distance. The driver output current is user selectable up to 100mA to drive different types of IR emitters LEDs. Six different modes of operation can be selected via the I2C interface: Programmable ALS once with auto power-down, programmable IR sensing once, programmable proximity sensing once, programmable continuous ALS sensing, programmable continuous IR sensing and programmable continuous proximity sensing. The programmable one-time operation modes greatly reduce power because an immediate automatic shutdown reduces overall supply current less than 1A. Designed to operate on supplies from 2.25V to 3.3V, the ISL29015 is specified for operation over the -40C to +85C ambient temperature range. It is packaged in a clear, Pb-free 6 Ld ODFN package.
Features
Proximity Sensing * Ambient IR Cancellation During Proximity Sensing - Works Under Direct Sunlight * IR LED Driver with Programmable Source Current - Adjustable Current Drive from 100mA to 12.5mA * Programmable LED current Modulation Frequency * Variable Conversion Resolution up to 16-bits Ambient Light Sensing * Simple Output Code Directly Proportional to lux * Adjustable Sensitivity up to 65 Counts per lux * Selectable Range (via I2C) - Range 1 = 0.015 lux to 1,000 lux - Range 2 = 0.06 lux to 4,000 lux - Range 3 = 0.24 lux to 16,000 lux - Range 4 = 0.96 lux to 64,000 lux * Integrated 50/60Hz Noise Rejection * Works Under Various Light Sources, Including Sunlight Ideal Spectral Response for Light and Proximity Sensor * Light Sensor Close to Human Eye Response - Excellent Light Sensor IR and UV Rejection * Proximity sensor range from 850nm to 950nm - Can use either 850nm or 950nm LED solution Ultra Low Power * 90A Max Operating Current - 1.0A Max Shutdown Current * Software Shutdown and Automatic Shutdown Easy to Use * I2C (SMBus Compatible) Output * No Complex Algorithms Needed * Temperature Compensated * Small Form Factor - 2.0x2.1x0.7mm 6 Ld ODFN Package Additional Features * * * * I2C and SMBus Compatible 1.7V to 3.63V Supply for I2C Interface 2.25V to 3.3V Supply Pb-Free (RoHS compliant)
Pinout
ISL29015 (6 LD ODFN) TOP VIEW
Applications
6 IRDR 5 SDA 4 SCL
VDD 1 GND 2 REXT 3
* Display and Keypad Dimming Adjustment and Proximity Sensing for: - Mobile Devices: Smart Phone, PDA, GPS - Computing Devices: Notebook PC, Webpad - Consumer Devices: LCD-TV, Digital Picture Frame, Digital Camera * Industrial and Medical Light and Proximity Sensing
*EXPOSED PAD CAN BE CONNECTED TO GND OR ELECTRICALLY ISOLATED
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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. 2008. All Rights Reserved. All other trademarks mentioned are the property of their respective owners.
ISL29015 Ordering Information
PART NUMBER (Note) ISL29015IROZ-T7* ISL29015IROZ-EVALZ TEMP. RANGE (C) -40 to +85 Evaluation Board PACKAGE (Pb-Free) 6 Ld ODFN PKG. DWG. # L6.2x2.1
*Please refer to TB347 for details on reel specifications. NOTE: 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.
Pin Descriptions
PIN NUMBER 1 2 3 4 5 6 PIN NAME VDD GND REXT SCL SDA IRDR Positive supply: 2.25V to 3.3V. Ground pin. External resistor pin setting the internal reference current and the conversion time. 499k with 1% tolerance resistor is recommended. I2C serial clock line I2C serial data line IR LED driver pin connecting to the anode of the external IR LED. The source current of the IR LED driver can be programmed through I2C. Exposed pad connected to ground or electrically isolated. The I2C bus lines can be pulled from 1.7V to above VDD, 3.63V max. DESCRIPTION
Block Diagram
VDD 1 PHOTODIODE ARRAY COMMAND REGISTER LIGHT DATA PROCESS ALS AND IR IR PHOTODIODE ARRAY IREF FOSC IR DRIVER 6 IRDR INTEGRATION ADC DATA REGISTER 5 I2C 4 SDA SCL
3 REXT
2 GND ISL29015
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ISL29015
Absolute Maximum Ratings (TA = +25C)
VDD Supply Voltage between VDD and GND . . . . . . . . . . . . . 3.6V I2C Bus (SCL, SDA) Pin Voltage . . . . . . . . . . . . . . . . . . -0.2V to 4V I2C Bus (SCL, SDA) Pin Current . . . . . . . . . . . . . . . . . . . . . <10mA IRDR Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . -0.2V to VDD + 0.5V REXT Pin Voltage . . . . . . . . . . . . . . . . . . . . . . . . -0.2V to VDD + 0.5V ESD Rating Human Body Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2kV
Thermal Information
Thermal Resistance (Typical, Note 1) JA (C/W) 6 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.
NOTE: 1. 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.
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 IDD IDD1 VI2C fOSC tint FI2C DATA_0 DATA_FS DATA DATA DATA_1 DATA_2 DATA_3 DATA_4 DATA_IR1 DATA_IR2 DATA_IR3 DATA_IR4 VREF VIL VIH
VDD = 3V, TA = +25C, REXT = 499k 1% tolerance, 16-bit ADC operation, unless otherwise specified. CONDITION MIN 2.25 0.1 70 1.7 650 16-bit ADC data 725 90 1 to 400 E = 0 lux 1 5 65535 Ambient light sensing 10 TYP MAX 3.3 1 90 3.63 800 UNIT V A A V kHz ms kHz Counts Counts %
DESCRIPTION Power Supply Range
Supply Current when Powered Down Software disabled or auto power-down Supply Current of Ambient Light and IR Sensing Supply Voltage Range for I2C Interface Internal Oscillator Frequency ADC Integration/Conversion Time I2C Clock Rate Range Count Output When Dark Full Scale ADC Code Count Output Variation Over Three Light Sources: Fluorescent, Incandescent and Sunlight Light Count Output With LSB of 0.015 lux/count Light Count Output With LSB of 0.06 lux/count Light Count Output With LSB of 0.024 lux/count Light Count Output With LSB of 0.96 lux/count Infrared Count Output Infrared Count Output Infrared Count Output Infrared Count Output Voltage of REXT Pin SCL and SDA Input Low Voltage SCL and SDA Input High Voltage 1.5
E = 300 lux, Fluorescent light (Note 2), Ambient light sensing, Range 1 (1k lux) E = 300 lux, Fluorescent light (Note 2), Ambient light sensing, Range 2 (4k lux) E = 300 lux, Fluorescent light (Note 2), Ambient light sensing, Range 3 (16k lux) E = 300 lux, Fluorescent light (Note 2), Ambient light sensing, Range 4 (64k lux) E = 210 lux, Sunlight (Note 3), IR sensing, Range 1 E = 210 lux, Sunlight (Note 3), IR sensing, Range 2 E = 210 lux, Sunlight (Note 3), IR sensing, Range 3 E = 210 lux, Sunlight (Note 3), IR sensing, Range 4
15000
20000 5000 1250 312
25000
Counts Counts Counts Counts
15000
20000 5000 1250 312 0.52
25000
Counts Counts Counts Counts V
0.6
V V
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Electrical Specifications
PARAMETER ISDA IIRDR1 IIRDR2 IIRDR3 IIRDR4 VIRLED tr tf fIRLED1 fIRLED2 IDD (IRLED1) IDD (IRLED2) Duty Cycle PROX-IR PROX NOTES: 2. 550nm green LED is used in production test. The 550nm LED irradiance is calibrated to produce the same DATA count against an illuminance level of 300 lux fluorescent light. 3. 850nm infrared LED is used in production test. The 850nm LED irradiance is calibrated to produce the same DATA_IR count against an illuminance level of 210 lux sunlight at sea level. 4. See "Register Set" on page 6. VDD = 3V, TA = +25C, REXT = 499k 1% tolerance, 16-bit ADC operation, unless otherwise specified. (Continued) CONDITION MIN 4 IS<1:0> = 0 (Note 4) IS<1:0> = 1 (Note 4) IS<1:0> = 2 (Note 4) IS<1:0> = 3 (Note 4) 1.5V at IRDR pin 44 TYP 5 100 50 25 12.5 VDD - 0.6 RLOAD = 15 at IRDR pin, 20% to 80% RLOAD = 15 at IRDR pin, 80% to 20% Freq<1:0> = 0 (Note 4) Freq<1:0> = 3 (Note 4) 35 10 DC 360 101 51 50 IR and proximity sensing with Range 2; 1.5V @ IRDR pin, IS<1:0> = 0, Freq<1:0> = 0; E = 210 lux, Sunlight. 2.0 56 MAX UNIT mA mA mA mA mA V ns ns kHz kHz mA mA % %
DESCRIPTION SDA Current Sinking Capability IRDR Source Current IRDR Source Current IRDR Source Current IRDR Source Current Voltage Head Room of IRDR Pin Rise Time for IRDR Source Current Fall Time for IRDR Source Current IR LED Modulation Frequency IR LED Modulation Frequency
Supply Current of Proximity Sensing IS<1:0> = 0, Freq<1:0> = 0 (Note 4) Supply Current of Proximity Sensing IS<1:0> = 0, Freq<1:0> = 3 (Note 4) Duty Cycle of IR LED Modulation Differential ADC Output of IR and Proximity Sensing With Object Far Away to Provide No Reflection
Principles of Operation
Photodiodes and ADC
The ISL29015 contains two photodiode arrays which convert light into current. The spectral response for ambient light sensing and IR sensing is shown in Figure 6 in the performance curves section. After light is converted to current during the light signal process, the current output is converted to digital by a built-in 16-bit Analog-to-Digital Converter (ADC). An I2C command reads the ambient light or IR intensity in counts. The converter is a charge-balancing integrating type 16-bit ADC. The chosen method for conversion is best for converting small current signals in the presence of an AC periodic noise. A 100ms integration time, for instance, highly rejects 50Hz and 60Hz power line noise simultaneously. The built-in ADC offers user flexibility in integration time or conversion time. There are two timing modes: Internal Timing Mode and External Timing Mode. In Internal Timing Mode, integration time is determined by an internal oscillator (fOSC), and the n-bit (n = 4, 8, 12,16) counter inside the ADC. In External Timing Mode, integration time is determined by the time between two consecutive I2C External Timing Mode commands. See "Integration and Conversion Time" on page 7. A good balancing act of integration time and resolution depending on the application is required for optimal results.
The ADC has I2C programmable range select to dynamically accommodate various lighting conditions. For very dim conditions, the ADC can be configured at its lowest range (Range 1) in the ambient light sensing. For very bright conditions, the ADC can be configured at its highest range (Range 4) in the proximity sensing.
Low-Power Operation
The ISL29015 initial operation is at the power-down mode after a supply voltage is provided. The data registers contain the default value of 0. When the ISL29015 receives an I2C command to do a one-time measurement from an I2C master, it will start ADC conversion with light or proximity sensing. It will go to the power-down mode automatically after one conversion is finished and keep the conversion data available for the master to fetch anytime afterwards. The ISL29015 will continuously do ADC conversion with light or proximity sensing if it receives an I2C command of continuous measurement. It will continuously update the data registers with the latest conversion data. It will go to the power-down mode after it receives the I2C command of power-down.
Ambient Light, IR and Proximity Sensing
There are six operational modes in ISL29015: Programmable ALS once with auto power-down, programmable IR sensing once with auto power-down, programmable proximity sensing once with auto power-down; programmable continuous ALS sensing, programmable continuous IR sensing and
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ISL29015
programmable continuous proximity sensing. These six modes can be programmed in series to fulfill the application needs. The detailed program configuration is listed in "Register Set" on page 6. When the part is programmed for ambient light sensing, the ambient light with wavelength within the "Ambient Light Sensing" spectral response curve in Figure 6 is converted into current. With ADC, the current is converted to an unsigned n-bit (up to 16 bits) digital output. When the part is programmed for infrared (IR) sensing, the IR light with wavelength within the "IR or Proximity Sensing" spectral response curve on Figure 6 is converted into current. With ADC, the current is converted to an unsigned n-bit (up to 16 bits) digital output. When the part is programmed for proximity sensing, the external IR LED is turned on by the built-in IR LED driver through the IRDR pin. The amplitude of the IR LED current and the IR LED modulation frequency can be programmed through Command Register II. When the IR from the LED reaches an object and gets reflected back, the reflected IR light with wavelength within the "IR or Proximity Sensing" spectral response curve in Figure 6 is converted into current. With ADC, the current is converted to an unsigned n-bit (up to 16 bits) digital output. The output reading is inversely proportional to the square of the distance between the sensor and the object. When there is significant background IR noise like direct sunlight, both IR and proximity sensing can be implemented for background noise cancellation. The differential output reading from the ADC decreases with distance.
I2C DATA I2C SDA IN I2C SDA OUT I2C CLK START DEVICE ADDRESS WA REGISTER ADDRESS
I2C Interface
There are four 8-bit registers available inside the ISL29015. The two command registers define the operation of the device. The command registers do not change until the registers are overwritten. The two 8-bit data Read Only registers are for the ADC output. The data registers contain the ADC's latest digital output, or the number of clock cycles in the previous integration period. The ISL29015's I2C interface slave address is internally hardwired as 1000100. When 1000100x with x as R or W is sent after the Start condition, this device compares the first seven bits of this byte to its address and matches. Figure 1 shows a sample one-byte read. Figure 2 shows a sample one-byte write. The I2C bus master always drives the SCL (clock) line, while either the master or the slave can drive the SDA (data) line. Figure 2 shows a sample write. Every I2C transaction begins with the master asserting a start condition (SDA falling while SCL remains high). The following byte is driven by the master, and includes the slave address and read/write bit. The receiving device is responsible for pulling SDA low during the acknowledgement period. Every 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.
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 ISL29015
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A
SDA DRIVEN BY MASTER
A D7 D6 D5 D4 D3 D2 D1 D0
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 1. I2C READ TIMING DIAGRAM SAMPLE
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START I2C DATA I2C SDA IN A6 A5 A4 A3 A2 A1 A0 W A R7 R6 R5 R4 R3 R2 R1 R0 A B7 B6 B5 B4 B3 B2 B1 B0 A DEVICE ADDRESS W A REGISTER ADDRESS A FUNCTIONS A STOP
I2C SDA OUT SDA DRIVEN BY MASTER I2C CLK IN 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 A SDA DRIVEN BY MASTER A SDA DRIVEN BY MASTER A
FIGURE 2. I2C WRITE TIMING DIAGRAM SAMPLE
Register Set
There are four registers that are available in the ISL29015. Table 1 summarizes their functions.
TABLE 1. REGISTER SET BIT ADDR 00h 01h 02h 03h REG NAME COMMANDI COMMANDII DATALSB DATAMSB 7 OP2 IS1 D7 D15 6 OP1 IS0 D6 D14 5 OP0 FREQ1 D5 D13 4 0 FREQ0 D4 D12 3 0 RES1 D3 D11 2 0 RES0 D2 D10 1 0 RANGE1 D1 D9 0 0 RANGE0 D0 D8 DEFAULT 00h 00h 00h 00h
Command Register I 00(hex)
The first command register has the following functions: 1. Operation Mode: Bits 7, 6, and 5.These three bits determines the operation mode of the device.
TABLE 2. OPERATION MODE BITS 7 TO 5 000 001 010 011 100 101 110 111 ALS once IR once Proximity once Reserved ALS continuous IR continuous Proximity continuous OPERATION Power-down the device
For example, the device sources 100mA out of the IRDR pin if Bits 7 and 6 are 0 during proximity sensing.
TABLE 3. CURRENT SOURCE CAPABILITY AT IRDR PIN BITS 7: 6 00 01 10 11 IRDR PIN SOURCE CURRENT 100mA IR LED driver 50mA IR LED driver 25mA IR LED driver 12.5mA IR LED driver
2. Modulation Frequency: Bits 5 and 4. These two bits set the IR LED driver's modulation frequency.
TABLE 4. MODULATION FREQUENCY BITS 5:4 00 01 10 11 MODULATION FREQUENCY (kHz) DC N/A N/A 360
2. Bit 4 to 0 has been reserved to 0.
Command Register II 01(hex)
The second command register has the following functions: 1. Amplitude of IR driver current: Bits 7 and 6. This device provides current source to drive an external IR LED. The drive capability can be programmed through Bits 7 and 6.
3. Resolution: Bits 3 and 2. Bits 3 and 2 determine the ADC's resolution and the number of clock cycles per conversion in Internal Timing Mode. Changing the number of clock cycles does more than just change the resolution of the device. It also changes the integration time, which is the period the device's analog-to-digital
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(A/D) converter samples the photodiode current signal for a measurement.
.
Here, Range(k) is defined in Table 6. Countmax is the maximum output counts from the ADC. The transfer function used for n-bit ADC becomes:
TABLE 5. RESOLUTION/WIDTH BITS 3:2 00 01 10 11 NUMBER OF CLOCK CYCLES 216 = 65,536 212 = 4,096 28 = 256 24 = 16 n-BIT ADC 16 12 8 4
Range ( k ) E cal = --------------------------- x DATA n 2
(EQ. 3)
4. Range: Bits 1 and 0. The Full Scale Range (FSR) can be adjusted via I2C using Bits 1 and 0. Table 6 lists the possible values of FSR for the 499k REXT resistor.
TABLE 6. RANGE/FSR LUX BITS 1:0 00 01 10 11 k 1 2 3 4 RANGE(k) Range1 Range2 Range3 Range4 FSR (LUX) @ ALS SENSING 1,000 4,000 16,000 64,000 FSR @ IR SENSING Refer to page 3 Refer to page 3 Refer to page 3 Refer to page 3
Here, n = 4, 8, 12 or 16. This is the number of ADC bits programmed in the command register. 2n represents the maximum number of counts possible from the ADC output. Data is the ADC output stored in the data registers (02 hex and 03 hex).
Integration and Conversion Time
The ADC resolution and fOSC determines the integration time, tint.
(EQ. 4)
R EXT n n 1 t int = 2 x ------------- = 2 x --------------------------------------------725kHz x 499k f OSC
where n is the number of bits of resolution and n = 4, 8, 12 or 16. 2n, therefore, is the number of clock cycles. n can be programmed at the command register 01(hex) bits 3 and 2.
TABLE 8. INTEGRATION TIME OF n-BIT ADC REXT (k) 250 499** n = 16-BIT 45ms 90ms n = 12-BIT 2.812ms 5.63ms n = 8-BIT 175.5s 351s n = 4-BIT 10.8s 21.6s
Data Registers (02 hex and 03 hex)
The device has two 8-bit read-only registers to hold the data from LSB to MSB for ADC. The most significant bit (MSB) is accessed at 03 hex, and the least significant bit (LSB) is accessed at 02 hex. For 16-bit resolution, the data is from D0 to D15; for 12-bit resolution, the data is from D0 to D11; for 8-bit resolution, the data is from D0 to D7. The registers are refreshed after every conversion cycle.
TABLE 7. DATA REGISTERS ADDRESS (hex) 02 03 CONTENTS D0 is LSB for 4, 8, 12 or 16-bit resolution, D3 is MSB for 4-bit resolution, D7 is MSB for 8-bit resolution D15 is MSB for 16-bit resolution, D11 is MSB for 12-bit resolution
**Recommended REXT resistor value
External Scaling Resistor REXT for fOSC and Range
The ISL29015 uses an external resistor REXT to fix its internal oscillator frequency, fOSC and the light sensing range. fOSC and Range are inversely proportional to REXT. For user simplicity, the proportionality constant is referenced to 499k:
499k Range = ----------------- x Range ( k ) R EXT 499k f OSC = ----------------- x 725 kHz R EXT (EQ. 5)
(EQ. 6)
Calculating Lux
The ISL29015's ADC output codes, DATA, are directly proportional to lux in the ambient light sensing.
E cal = x DATA (EQ. 1)
Noise Rejection
In general, integrating type ADC's have excellent noise-rejection characteristics for periodic noise sources whose frequency is an integer multiple of the conversion rate. For instance, a 60Hz AC unwanted signal's sum from 0ms to k*16.66ms (k = 1,2...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.
Here, Ecal is the calculated lux reading. The constant is determined by the Full Scale Range and the ADC's maximum output counts. The constant is independent on the light sources (fluorescent, incandescent and sunlight) because of the light sources' IR component is removed during the light signal process. The constant can also be viewed as the sensitivity: the smallest lux measurement the device can measure is shown in Equation 2.
Range ( k ) = ---------------------------Count max (EQ. 2)
ADC Output in IR Sensing
The ISL29015's ADC output codes, DATA, are directly proportional to the IR intensity received in the IR sensing phase.
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DATA IR = x E IR (EQ. 7)
Here, EIR is the received IR intensity. The constant changes with the spectrum of background IR noise like sunlight and incandescent light. The also changes with the ADC's range and resolution selections.
during the entire operation cycle that includes ALS, IR sensing and Proximity sensing three different serial phases, the detection occurs once every 30ms, the average current consumption including external IR LED drive current can be calculated from Equation 9:
[ ( 0.05mA + 0.05mA + 1mA + (50mA 50%)) 0.4ms ) ]/30ms = 0.35mA
ADC Output in Proximity Sensing
In the proximity sensing, the ADC output codes, DATA, are directly proportional to the total IR intensity from the background IR noise and from the IR LED driven by the ISL29015.
DATA PROX = x E IR + x E LED (EQ. 8)
(EQ. 9)
If at a 12-bit ADC resolution where the integration time for each serial phase becomes 7ms and the total detection time becomes 100ms, the average current can be calculated from Equation 10:
[ ( 0.05mA + 0.05mA + 1mA + (50mA 50%)) 7ms ) ]/100ms = 1.83mA
(EQ. 10)
and EIR in Equation 8 have the same meanings as in Equation 7. The constant depends on the spectrum of the used IR LED and the ADC's range and resolution selections. ELED is the IR intensity which is emitted from the IR LED and reflected by a specific objector to the ISL29015. ELED depends on the current to the IR LED and the surface of the object. ELED decreases with the square of the distance between the object and the sensor. If background IR noise is small, i.e., EIR can be neglected, the ADC output directly decreases with the distance. If there is significant background IR noise, the sequence of the proximity sensing followed by the IR sensing can be implemented. The differential reading of ADC outputs from the proximity and IR sensing has no effect of background IR noise and directly decreases with the distance between the object and the sensor. Please refer to "Typical Performance Curves" on page 10 for ADC output vs distance. Figure 9 shows ISL29015 configured at 12-bit ADC resolution, 12.5mA external LED current at 327.7KHz modulation frequency, detects three different sensing objects: 92% brightness paper, 18% gray card and ESD black foam. Figure 10 shows ISL29015 configured at 12-bit ADC resolution, programmed external LED at 327.7KHz modulation frequency, detects the same sensing object: 18% gray card under four different external LED current: 12.5mA, 25mA, 50mA and 100mA to compare the proximity readout versus distance.
Suggested PCB Footprint
It is important that the 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 ISL29015 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. Use two power-supply decoupling capacitors, 1F and 0.1F, placed close to the device.
Typical Circuit
A typical application for the ISL29015 is shown in Figure 4. The ISL29015's I2C address is internally hardwired as 1000100. The device can be tied onto a system's I2C bus together with other I2C compliant devices.
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.
Current Consumption Estimation
The low power operation is achieved through sequential readout in the serial fashion, as shown in Figure 3, the device requires three different phases in serial during the entire detection cycle to do ambient light sensing, infrared sensing and proximity sensing. The external IR LED will only be turned on during the proximity sensing phase under user program controlled current at modulated frequency depends on user selections. Figure 3 also shows the current consumption during each ALS, IR sensing and Proximity sensing phase. For example, at 8-bit ADC resolution the integration time is 0.4ms. If user programed 50mA current to supply external IR LED at 327.7kHz modulated frequency,
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30ms 1s ALS 0.4ms 50A
IR
0.4ms
50A
PROXIMITY
0.4ms
1mA
IR LED 327.7 kHz
50mA
FIGURE 3. CURRENT CONSUMPTION FOR EACH INTEGRATION PHASE AND DETECTION CYCLE
1.7V TO 3.63V R1 10k R2 10k I2C MASTER MICROCONTROLLER SDA SCL
2.25V TO 3.3V
I2C SLAVE_0 1 2 C1 1F C2 0.1F 3 VDD GND REXT IRDR SDA SCL 6 5 4
I2C SLAVE_1 SDA SCL
I2C SLAVE_n SDA SCL
REXT ISL29015 499k
FIGURE 4. ISL29015 TYPICAL CIRCUIT
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ISL29015 Typical Performance Curves
1.2 SUN NORMALIZED LIGHT INTENSITY NORMALIZED RESPONSE 1.0 0.8 0.6 0.4 0.2 0 300 FLUORESCENT INCANDESCENT
VDD = 3V, Rext = 499k
1.2 1 0.8 0.6 0.4 0.2 0 -0.2 300 AMBIENT LIGHT SENSING HUMAN EYE RESPONSE
HALOGEN
IR AND PROXIMITY SENSING
400
500
600 700 800 WAVELENGTH (nm)
900
1000
1100
400
500
600 700 800 900 WAVELENGTH (nm)
1000
1100
FIGURE 5. SPECTRUM OF FOUR LIGHT SOURCES
FIGURE 6. SPECTRAL RESPONSE FOR AMBIENT LIGHT SENSING AND PROXIMITY SENSING
RADIATION PATTERN 20 LUMINOSITY 30 ANGLE 40 50 60 70 80 90 0.2 0.4 0.6 0.8 RELATIVE SENSITIVITY 10 0 10 20 30 40 50 60 70 80 90 1.0
CALCULATED ALS READING (LUX)
1000 900 800 700 600 500 400 300 200 100 0 0 Ecal = FLUORESCENT 1000 LUX 216 VDD = 3V RANGE = 1000 LUX 16-BIT ADC HALOGEN INCANDESCENT
65535 ADC OUTPUT (COUNT)
32768
x DATA
0 100 200 300 400 500 600 700 800 900 1000 LUX METER READING (LUX)
FIGURE 7. RADIATION PATTERN
FIGURE 8. SENSITIVITY TO FOUR LIGHT SOURCES
10000 92% BRIGHTNESS PAPER DATAPROX-DATAIR 1000 18% GRAY CARD 100 DATAPROX-DATAIR (COUNT)
4500 4000 3500 3000 2500 2000 1500 1000 500 0 0 10 20 30 40 50 60 DISTANCE (mm) 70 80 90 IIRLED = 100mA IIRLED = 50mA IIRLED = 25mA IIRLED = 12.5mA
10 ESD BLACK FOAM 1
0
20
40 60 DISTANCE (mm)
80
100
FIGURE 9. ADC OUTPUT vs DISTANCE WITH DIFFERENT OBJECTS IN PROXIMITY SENSING
FIGURE 10. ADC OUTPUT vs DISTANCE WITH DIFFERENT LED CURRENT AMPLITUDES IN PROXIMITY SENSING
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ISL29015 Typical Performance Curves
10
OUTPUT CODE (COUNTS)
VDD = 3V, Rext = 499k (Continued)
OUTPUT CODE RATIO (FROM +30C) 1.10 300 Lux FLUORESCENT LIGHT ALS SENSING 1.05
8
6
1.00
4
2
0.95
0 -60
-20
20 TEMPERATURE (C)
60
100
0.90 -60
-20
20 TEMPERATURE (C)
60
100
FIGURE 11. OUTPUT CODE FOR 0 LUX vs TEMPERATURE
FIGURE 12. OUTPUT CODE vs TEMPERATURE
105.0 IRDR OUTPUT CURRENT (mA) 104.5 104.0 103.5 103.0 102.5 102.0 101.5 101.0 100.5 100.0 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100 120 PROXIMITY SENSING IS<1:0> = 0 SUPPLY CURRENT (A)
90 85 80 75 70 65 60 -40 ALS SENSING 10,000 Lux
-20
0
20 40 60 TEMPERATURE (C)
80
100
120
FIGURE 13. OUTPUT CURRENT vs TEMPERATURE IN PROXIMITY SENSING
FIGURE 14. SUPPLY CURRENT vs TEMPERATURE IN ALS SENSING
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FN6522.0 October 31, 2008
ISL29015
FIGURE 15. 6 LD ODFN SENSOR LOCATION OUTLINE
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed 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 12
FN6522.0 October 31, 2008
ISL29015
Package Outline Drawing
L6.2x2.1
6 LEAD OPTICAL DUAL FLAT NO-LEAD PLASTIC PACKAGE (ODFN) Rev 0, 9/06
2.10 A 6 B PIN 1 INDEX AREA
1
6 PIN 1 INDEX AREA 0.65 2.00
1. 35
1. 30 REF
(4X)
0.10
6X 0. 30 0. 05
0. 65
TOP VIEW
6X 0. 35 0. 05
BOTTOM VIEW
0.10 M C A B
(0. 65) MAX 0.75 SEE DETAIL "X" 0.10 C (0. 65) (1. 35) BASE PLANE (6X 0. 30) SIDE VIEW SEATING PLANE 0.08 C C
(6X 0. 55) C (1. 95) 0 . 00 MIN. 0. 05 MAX. DETAIL "X" 0. 2 REF 5
TYPICAL RECOMMENDED LAND PATTERN
NOTES: 1. Dimensions are in millimeters. Dimensions in () for Reference Only. 2. Dimensioning and tolerancing conform to AMSE Y14.5m-1994. 3. Unless otherwise specified, tolerance: Decimal 0.05 4. Dimension b applies to the metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 5. Tiebar shown (if present) is a non-functional feature. 6. The configuration of the pin #1 identifier is optional, but must be located within the zone indicated. The pin #1 identifier may be either a mold or mark feature.
13
FN6522.0 October 31, 2008

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