AMI AMIS

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
Pin No.
I, O or IO
I2CCLK
3
I
I2CDATA
4
IO
VDD
VSS
5
1
I
I
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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
1
Comments
AMIS–749803: (I2C) Ambient Light Sensor
4.0 Spectral Response
Figure 1: Photo Diode Spectral Response (Without Filter)
Figure 2: Simulated Human Eye Spectral Response
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Data Sheet
AMIS–749803: (I2C) Ambient Light Sensor
Figure 3: Photo Diode Spectral Response (With Green Filter)
Figure 4: Fluorescent Light Response
Figure 5: Incandescent Light Response
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Data Sheet
AMIS–749803: (I2C) Ambient Light Sensor
Figure 6: Direct Sunlight Response
Figure 7: Sunlight Response (Through Attenuating Filter)
Figure 8: Response versus VDD
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Data Sheet
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 ..…………………………. 0°C to 70°C
Storage temperature range, Tstg……………….…………………….. -40°C to 85°C
ESD tolerance, human body model…………………………………. 2000V
Note:
All voltages are with respect to VSS.
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.
Figure 9: AC Characteristics
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Data Sheet
Unit
kHz
µS
µS
µS
µS
µS
nS
nS
nS
µS
µS
pF
V
V
AMIS–749803: (I2C) Ambient Light Sensor
Table 4: Operating Characteristics, VDD = 3.3V, TA = 25°C (unless otherwise noted)
Parameter
Test Conditions
Min.
Typ.
Re irradiance responsivity
550
λp (see Figure 3)
Fluorescent light source:
109
Ev = 100lux (see Figure 4)
Rv illuminance responsivity
Fluorescent light source:
1275
Ev = 1000lux (see Figure 4)
Rv illuminance responsivity
Rv illuminance responsivity
Rv illuminance responsivity
Rv illuminance responsivity
Dark current
Incandescent light source:
Ev = 100lux (see Figure 5)
Max.
Data Sheet
Units
nM
Counts
125
Counts
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)
1120
100
Counts
995
37
Counts
375
To be
provided
Ev = 0lux (see Figure 16)
Counts
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
16-bits
hν
Control
I2C serial
interface
Figure 10: Block Diagram
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I2CCLK
I2CDATA
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)
Equation 1
where Ik = 3.3357
Hence the intensity of the ambient light, IL(in lux):
IL = Cnt / (3.3357 * Ti)
Equation 2
For example let:
Cnt = 1001
Ti = 300mS
Intensity of the ambient light, IL(in lux):
IL = 1001 / (3.3357 * 300mS)
Equation 3
IL = 1000lux
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
hν
ADC
hν
16-bits
Control
I2C serial
interface
Figure 13: Measurement Set-up
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I2CCLK
I2CDATA
AMIS–749803: (I2C) Ambient Light Sensor
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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Data Sheet
AMIS–749803: (I2C) Ambient Light Sensor
10.0 Characteristics
Figure 16: Dark Current vs. Temperature
Figure 17: Dark Current vs. VDD
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Data Sheet
AMIS–749803: (I2C) Ambient Light Sensor
Figure 18: Power Dissipation vs. Temperature
Figure 19: Power Dissipation vs. Ev
Figure 20: Power Dissipation vs. VDD
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Data Sheet
AMIS–749803: (I2C) Ambient Light Sensor
Data Sheet
11.0 Application Information
Figure 21 and Figure 22 are illustrations of typical usage of the ALS device 749803 (I2C):
.
VDD
3.0V
to
3.6V
10µF
0.1µF
Rp
Rp
VSS
VDD
VSS
I2CDATA
PD
MCU
I2CCLK
749803 (I2C)
Figure 21: Typical usage, PD from MCU or SW control
VDD
3.0V to
3.6V
10µF
0.1µF
Rp
Rp
VSS
VSS
VDD
I2CDATA
PD
MCU
I2CCLK
749803 (I2C)
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 [email protected]
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 © 2006 AMI Semiconductor, Inc.
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