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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
1.0 General Description
The AMIS-74980x is a wide dynamic range family of ambient light sensors (ALS) with an analog or digital output. There are several versions of the ALS with analog output; one with 10uA current output at 1000lux all the way to 1mA at 1000lux. The digital output version has a built-in 16-bit ADC with a 2-wire SMBus or I2C digital interface. The sensor employs AMI Semiconductor's proprietary CMOS image sensing technology which provides low noise and high dynamic range output signals and a light response similar to the response of the human eye.
2 This data sheet provides details of the DC characteristics, AC characteristics and programming information of AMIS-749803 (I C) ALS.
2.0 Key Features
* * * * * * * * * * Senses ambient light and provides an output count proportional to the ambient light Human eye type of spectral response Standard CMOS process technology Low power consumption Linear response over the full operating range Senses intensity of ambient light from ~0lux to well over 100,000lux Built-in programmable integration times of 400ms, 200ms and 100ms Does not require any external components Built-in 16-bit ADC I2C serial port communication o Standard mode - 100kHz o Fast mode - 400kHz * Provides comfortable levels of display depending on the viewing environment Saves display power in applications such as: * Cell phone * PDA * MP3 player * GPS * Video recorder
3.0 Pin Out
Table 1: Pin Out Pin Name I2CCLK
Pin No. 3
I, O or IO I
I2CDATA VDD VSS
4 5 1
IO I I
Function This is the external I2C clock that is provided by the I2C master This bi-directional data signal is used for communication between this device and the I2C master This pin is the power pin This pin is the GND pin
Comments
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
4.0 Spectral Response
Figure 1: Photo Diode Spectral Response (Without Filter)
Figure 2: Simulated Human Eye Spectral Response
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
Figure 3: Photo Diode Spectral Response (With Green Filter)
Figure 4: Fluorescent Light Response
Figure 5: Incandescent Light Response
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
Figure 6: Direct Sunlight Response
Figure 7: Sunlight Response (Through Attenuating Filter)
Figure 8: Response versus VDD
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
5.0 Absolute Maximum Ratings
Over operating free-air temperature range (unless otherwise noted) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these conditions is not recommended. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. * * * * * * * Supply voltage, VDD ............................................................ 4V Input voltage high................................................................ VDD + 0.3V Input voltage low................................................................. -0.3V Digital output current, IO......................................................... 10mA Operating free-air temperature range, TA ................................. 0C to 70C Storage temperature range, Tstg............................................. -40C to 85C ESD tolerance, human body model........................................ 2000V
All voltages are with respect to VSS.
Note:
6.0 Electrical Characteristics
Table 2: DC Characteristics of I2CCLK and I2CDATA Signals in Standard and Fast Modes of Operation Parameter Symbol Standard Mode Fast Mode Min. Max. Min. Max. Power supply voltage (current VDD 3.0 3.6 3.0 3.6 version) Operating free-air temperature TA 0 70 0 70 Low level input voltage (VDD-related -0.5 0.3VDD -0.5 0.3VDD VIL input levels) High level input voltage (VDD-related VIH 0.7VDD 0.7VDD input levels) Hysteresis of Schmitt trigger inputs N/A N/A 0.05VDD Vhys (VDD > 2V) Low level output voltage (open drain) VOL1 0 0.4 0 0.4 at 3mA sink current (VDD > 2V) Output fall time from VIHmin to VILmax (2) (1) (2) with a bus capacitance from 10pF to tof 250 20 + 0.1Cb 250 400pF Input current of each IO pins with an input voltage between 0.1VDD and Ii -10 10 -10 10 0.9VDD Capacitance for each IO pin Ci 10 10
Notes: 1. 2.
Unit V C V V V V nS
uA pF
Cb = capacitance of one bus line in pF. The maximum tf for the I2CDATA and I2CCLK bus lines quoted in Table 3 (300ns) is longer than the specified maximum tof for the output stages (250ns). This allows series protection resistors (Rs) to be connected between the I2CDATA/I2CCLK pins and the I2CDATA/I2CCLK bus lines without exceeding the maximum specified tf.
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AMIS-749803: (I2C) Ambient Light Sensor
Table 3: AC Characteristics of I2CCLK and I2CDATA Signals in Standard and Fast Modes of Operation* Parameter Symbol Standard Mode Fast Mode Min. Max. Min. Max. I2CCLK clock frequency fSCL 0 100 0 400 Hold time (repeated) START condition. After this period, the first tHD;STA 4.0 0.6 clock pulse is generated Low period of I2CCLK clock tLOW 4.7 1.3 High period of I2CCLK clock tHIGH 4.0 0.6 Set-up time for a repeated START 4.7 0.6 tSU;STA condition Data hold time for I2C-bus devices tHD;DAT_d 0 3.45 0 0.9 Data set-up time tSU;DAT 250 100 Rise time of both I2CDATA and tr 1000 5 300 I2CCLK signals Fall time of both I2CDATA and 300 0.1 300 tf I2CCLK signals Set-up time for STOP condition tSU;STO 4.0 0.6 Bus free time between STOP and 4.7 1.3 tBUF START condition Capacitive load for each bus line Cb 400 400 Noise margin at the low level for each 0.1VDD 0.1VDD connected device (including VnL hysteresis) Noise margin at the high level for VnH 0.2VDD 0.2VDD each connected device (including hysteresis)
*All values referred to VIHmin and VILmax levels (see Table 2). Please refer to Figure 9 for more information on AC characteristics.
Data Sheet
Unit kHz S S S S S nS nS nS S S pF V
V
Figure 9: AC Characteristics
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AMIS-749803: (I2C) Ambient Light Sensor
Table 4: Operating Characteristics, VDD = 3.3V, TA = 25C (unless otherwise noted) Parameter Test Conditions Min. Typ. Re irradiance responsivity 550 p (see Figure 3) Fluorescent light source: 109 Ev = 100lux (see Figure 4) Rv illuminance responsivity Fluorescent light source: 1275 Ev = 1000lux (see Figure 4) Incandescent light source: Ev = 100lux (see Figure 5) Incandescent light source: Ev = 1000lux (see Figure 5) Sun light direct: 100 Ev = Lux (see Figure 6) Sun light direct: 1000 Ev = Lux (see Figure 6) Sun light shade (w/attenuating filter): Ev = 100lux (see Figure 7) Sun light shade (w/attenuating filter): Ev = 1000lux (see Figure 7) Ev = 0lux (see Figure 16) 125 Counts 1120 100 Counts 995 37 Counts 375 To be provided Counts
Data Sheet
Max.
Units nM Counts
Rv illuminance responsivity
Rv illuminance responsivity
Rv illuminance responsivity Rv illuminance responsivity Dark current
7.0 Device Operation
This device employs a sensitive photo diode which is fabricated in AMIS C3 standard CMOS process technology. The major components of this sensor are as shown in Figure 10. The photons which are to be detected are passed through an AMIS proprietary color filter. This color filter is used to limit all extraneous photons and thus perform a band pass filter operation on the incident wave front. Thus this filter transmits only those photons in the visible spectrum which are primarily detected by human eye. The photo response of this sensor is as shown in Figure 3.
749803 (I2C) ADC h
16-bits Control I2CCLK I2CDATA
I2C serial interface
Figure 10: Block Diagram
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
The ambient light signal that is detected by the photo diode is converted to digital signal using a variable slope integrating ADC. The ADC that is used in this device has a maximum resolution of 16-bits unsigned value. The 16-bit ADC value is then provided to the 2 control block which is also connected to the I C interface block. The following equation (eq-1) shows the relationship of output counts Cnt as a function of integration constant Ik, integration time Ti (in sec), and the intensity of the ambient light, IL(in lux): IL = Cnt / (Ik * Ti) where Ik = 3.3357 Hence the intensity of the ambient light, IL(in lux): IL = Cnt / (3.3357 * Ti) Equation 2 Equation 1
For example let: Cnt = 1001 Ti = 300mS Intensity of the ambient light, IL(in lux): IL = 1001 / (3.3357 * 300mS) IL = 1000lux Equation 3
8.0 I2C Interface
This device is capable of working as an I2C bus slave. Address of this device on I2C bus is always 0x39 (hexadecimal number 39). Registers of this device can be programmed by sending commands over I2C bus. Ambient light intensity count value can be obtained 2 by reading registers of this device. Ambient light intensity count is a sixteen bits wide number and hence two I C read operations are 2 needed. This device supports both the standard mode (100 Kbit/s) and the fast mode (400 Kbit/s) of I C. Figure 11 shows an I2C write 2 2 operation. To write to an internal register of this device a command must be sent by an I C master. As shown in Figure 11, the I C write command begins with a start condition. After the start condition, seven bits of address are sent MSB first. RD/WR_ command bit follows 2 the address bits. Upon receiving a valid address the device responds by driving I2CDATA low for an ACK. After receiving an ACK, I C 2 master sends eight bits of data with MSB first. Upon receiving eight bits of data the device generates an ACK. I C master terminates this write command with a stop condition.
Figure 11: I2C Write Command
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
Figure 12 shows a I2C read command sent by the master to the slave device. I2C read command begins with a start condition. After the start condition seven bits of address are sent by the master MSB first. After the address bits, RD/WR_ command bit is sent. For a read command the RD/WR_ bits is high. Upon receiving the address bits and RD/WR_ command bits the device responds with an ACK. After sending an ACK, the device sends eight bits of data MSB first. After receiving the data master terminates this transaction by issuing a NACK command to indicate that the master only wanted to read one byte from the device. The master generates a stop condition to end this transaction.
Figure 12: I2C Read Command
8.1 Programmer's Model Ambient light intensity count is obtained from this chip by issuing a fixed sequence of I2C commands. Integration time of this device is programmable by writing different values to the integration time register. Sections below describe what a programmer needs to know about issuing commands to the chip and register access.
8.2 Integration Time Register Table 5 describes integration time register. This register has three bits, EC[2:0]. Duration of integration time is controlled by these three bits.
Table 5: Integration Time Register EC[2] EC[1] EC[0] Operation 0 0 0 Normal mode of operation 0 0 1 Normal mode of operation 0 1 0 Normal mode of operation 0 1 1 Test mode 1 0 0 Simulation test mode use only 1 0 1 Reserved for future use 1 1 0 Reserved for future use 1 1 1 Reserved for future use
Integration Time 400ms 200ms (Default) 100ms 16.7ms 1.0ms
8.3 Programming Sequence and Command Summary This section describes supported commands and programming sequence. This device only supports single byte write and a single byte read I2C commands. Ambient light intensity count is a sixteen bits wide number. So to read the sixteen bits wide count, two I2C read commands are needed. Table 6 describes commands that this device supports. All of these commands have to be sent to a fixed address (0x39).
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AMIS-749803: (I2C) Ambient Light Sensor
Table 6: Device Commands Command 0x00h 0x03h 0x1Dh 0x18h 0x43h 0x83h 0x88h 0x90h
Data Sheet
Function Start reading of ADC data Complete reading of ADC data Change EC[0] to 0 Reset EC[2:0] to default value (001) Prepare ADC LS byte for reading Prepare ADC MS byte for reading Change EC[1] to 1 Change EC[2] to 1
8.4 Programming Sequence For reading sixteen bits wide Ambient light intensity count, please issue commands in the following sequence. 1. 2. 3. 4. 5. 6. Send I2C write command 0x00h Send I2C write command 0x03h (Steps 1 and 2 complete reading of ADC) Send I2C write command 0x43h Send I2C read byte command (Device returns LS byte of Count) Send I2C write command 0x83h Send I2C read byte command (Device returns MS byte of Count)
For changing integration time (for example to set integration time to 100ms), please issue commands in the following sequence: 1. Send I2C write command 0x1Dh (This command will toggle EC[0]) 2. Send I2C write command 0x88h (This command will toggle EC[1], now EC[2:0] = 010)
9.0 Measurement Set-up
749803 (I2C)
Pulse generator LED
h
ADC h
16-bits Control I2CCLK I2CDATA
I2C serial interface
Figure 13: Measurement Set-up
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
9.1 Rise and Fall Time of I2CDATA (output) 9.1.1. Rise Time (tr) CL = 15pF tr = 11.3nS
Figure 14: Rise Time (tr)
9.1.2. Fall Time (tf) CL = 15pF tf = 0.16nS
Figure 15: Fall Time (tf)
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
10.0 Characteristics
Figure 16: Dark Current vs. Temperature
Figure 17: Dark Current vs. VDD
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
Figure 18: Power Dissipation vs. Temperature
Figure 19: Power Dissipation vs. Ev
Figure 20: Power Dissipation vs. VDD
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AMIS-749803: (I2C) Ambient Light Sensor
11.0 Application Information
Figure 21 and Figure 22 are illustrations of typical usage of the ALS device 749803 (I2C): .
Data Sheet
VDD 3.0V to 3.6V 10F VSS VSS PD I2CCLK 749803 (I2C) VDD 0.1F Rp Rp
I2CDATA MCU
Figure 21: Typical usage, PD from MCU or SW control
VDD 3.0V to 3.6V 10F VSS VSS PD I2CCLK 749803 (I2C) VDD I2CDATA MCU 0.1F Rp Rp
Figure 22: Typical usage, PD through SW control
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AMIS-749803: (I2C) Ambient Light Sensor
Data Sheet
12.0 Company or Product Inquiries
For more information about AMI Semiconductor's image sensors, please send an email to image_sensors@amis.com. For more information about AMI Semiconductor's products or services visit our Web site at http://www.amis.com.
Production Technical Data - The information contained in this document applies to a product in production. AMI Semiconductor and its subsidiaries ("AMIS") have made every effort to ensure that the information is accurate and reliable. However, the characteristics and specifications of the product are subject to change without notice and the information is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify that data being relied on is the most current and complete. AMIS reserves the right to discontinue production and change specifications and prices at any time and without notice. Products sold by AMIS are covered by the warranty and patent indemnification provisions appearing in its Terms of Sale only. AMIS makes no other warranty, express or implied, and disclaims the warranties of noninfringement, merchantability, or fitness for a particular purpose. AMI Semiconductor's products are intended for use in ordinary commercial applications. These products are not designed, authorized, or warranted to be suitable for use in life-support systems or other critical applications where malfunction may cause personal injury. Inclusion of AMIS products in such applications is understood to be fully at the customer's risk. Applications requiring extended temperature range, operation in unusual environmental conditions, or high reliability, such as military or medical life-support, are specifically not recommended without additional processing by AMIS for such applications. Copyright (c) 2006 AMI Semiconductor, Inc.
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