Ambient Light Sensor ICs

Innovations Embedded
Sensors
Ambient Light Sensor ICs
for automatic light control processing
< LCD
ROHM MarketingUSA
TV / Displays
< LCD-equipped
Portable Devices
Selection Guide
Ambient Light Sensor ICs
from ROHM Semiconductor
ROHM ambient light sensor (ALS) ICs

Mobile Phones
are designed to control the brightness of

Digital Cameras
LED-backlighted LCD displays based on

Video Players
ambient light availability and brightness

PDAs

Notebook PCs

Car Navigation systems

LCD TVs

LCD Monitors /Displays
for optimum display visibility and energy
efficiency.
The compact ROHM ALS ICs are the
ideal choice for LCD-equipped portable
devices as well as LCD monitors and
ROHM’s advanced ambient light sensor
ICs are offered in ultra-small WSOF5 and
WSOF6 packages
high-definition (HDTV) backlighting
control.
Improved Visibility with Lower Power Consumption
Adjusting the backlight intensity to
compensate for variations in ambient light
level can save 50% or more of the total
between charges (“talk time”) and/or the
light sources. ROHM ALS ICs feature
ability to extend the device’s feature set.
industry-leading performance that
To provide superior performance,
combines stable operation regardless
power required to operate some portable
backlight brightness control must be
of the light source (from incandescent
electronic devices. This translates into
done in a uniform way over a wide
to sunlight) with superior light sensing
dramatic improvement in operating time
range of ambient light conditions and
accuracy.
 Stable
operation regardless of light source
ROHM ambient light sensor ICs deliver stable output
under a variety of light sources (e.g. incandescent,
fluorescent, sunlight).
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 Superior
light sensing accuracy
Unique laser trimming technology ensures high sensitivity
accuracy –– ±15% –– more than twice as precise as
conventional ICs, which can range from ±30% to ±55%.
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Ambient Light Sensor ICs
from ROHM Semiconductor
ROHM ambient light sensor ICs are
in a typical application, an external
ROHM Semiconductor ambient light
available in both analog and digital
resistor converts the output current to
sensors all operate over a temperature
configurations. The key features of
a voltage for input to an MCU which
range of -40 to 85°C to ensure stable
each type are highlighted in the next
in turn controls the LED driver. Direct
operation under extreme conditions.
two pages of this selection guide.
connection to an LED driver is also
Analog and digtial ALS ICs are each
ROHM analog ALS ICs have an output
possible (see page 6 for details).
offered in compact, surface-mount
current proportional to light (current
ROHM Digital ALS ICs output a 16-bit
packages. Package choices include the
sourcing) with a measurement range
(0 to ~65,535 lx) digital signal over a
utra-small WSOF5 (1.6x1.6x0.55 mm)
2
direct I C bus interface to the MCU.
of 0 to 100,000+ lux. As shown below,
or WSOF6 (3.0x1.6x0.7 mm).
Analog Output Ambient Light Sensor ICs
Bright Control
t%$
t18.
t*2C
Microcontroller
or
Baseband Processor
LED Driver
ALS (BH16xx)
ADC
WSOF5
*OUT
Driver
S/W
Light
GC1
GC2
Gain Control
Digital Output Ambient Light Sensor ICs
LED Driver
Microcontroller
or
Baseband Processor
*2C
*'
Driver
S/W
1.888.775.ROHM
SCL
ALS (BH17xx)
WSOF6
SDA
SCL
SDA
Light
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Ambient Light Sensor ICs
from ROHM Semiconductor
Analog Output Type
The BH16xx Series of analog ambient light sensors combine a
to make the appropriate trade-off between backlight intensity
number of innovations to provide exceptional performance over
and power consumption. A logic-enabled shutdown function is
a wide range of applications. ROHM’s proprietary trimming
also provided to further enhance power efficiency. In addition,
process and use of multiple photodiodes with different junction
the current souce output supports full rail-to-rail voltage
depths provides a stable output with little variation between
operation, further improving control sensitivity to variations in
various light sources. Three levels of gain enable the designer
light intensity.
Uniform Sensitivity
Built-in Shutdown Function
1: Connect to VCC
0: Connect to GND
Three-Step Output Gain
Wide Output Range
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Ambient Light Sensor ICs
from ROHM Semiconductor
Digital (16-bit Serial) Output Type
The BH17xx series of digital ambient light sensors ICs employ
Two measurement resolution levels are provided, allowing
the same proprietary trimming and multiple photodiodes to
design trade-offs between sampling time and performance.
assure uniform light sensitivity. The device’s 16-bit analog-to-
For example, with high-resolution sampling, optical noise like
digital converter produces 1 lux resolution over a range of 0
fluorescent lamp flicker can be filtered. Low resolution reduces
2
to 65,000 lx. The I C output is designed for direct connection
the sampling time for applications like GPS systems where the
to the system’s microcontroller or baseband processor.
light level changes are dynamic.
50Hz/60Hz Optical Noise Elimination
Uniform Sensitivity
Optical Window Sensitivity Control
Wide I2C Input Voltage
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ROHM’s I2C bus is compatible with operating
voltages between 1.65V and Vcc (3.6V, max)
enabling operation in systems with multiple
power supplies.
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Ambient Light Sensor ICs
Design Tools
Ambient Light Sensor Evaluation Kits
Evaluation kits for ROHM analog and
digital ALS ICs are coming soon. Each kit
Sensitivity
setting
IC communication
display
consists of a USB-connected PC board
and a CD-ROM with software provided
Measurement
illuminance
display
to simulate and measure ambient light
response.
For more information, go to:
www.rohmsemiconductor.com/als.html
Optical Window Design Support
Applying an ALS requires both optical
and semiconductor expertise to assure
mounting of the IC with a suitable optical
window for light reception. ROHM’s
“Optical Window Design Manual”
ROHM’s ambient light sensor
Optical Window Design Manual
provides design guidance to facilitate the
ROHM’s ambient light sensor IC
Optical Simulation Report
design process.
For more information, go to:
www.rohmsemiconductor.com/als.html
Simplified Ambient light Control
The ROHM BD16xx Series ALS ICs are
designed to interface directly to ROHM
LED drivers (BD60xxGU) to automatically
2
IC
I/F
SCL
SDA
control white LED backlights in portable
devices without any requirement for
light control software. An MCU is not
Microcontroller
or
Baseband Processor
CPU Load
Reduced
ROHM LED Driver IC
with Automatic Light
Control Function
(BD6086GU)
(BD6095GUL)
Ambient
light
output
IOUT
Ambient light
sensor IC
(BH16xx series)
Performs light
output processing
Light
necessary but may still be used to
GC1
GC2
provide control input to the ALS gain and
Gain Switching
Shutdown
shutdown functions, as shown.
For more information, go to:
www.rohmsemiconductor.com/als.html
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Ambient Light Sensor ICs
Part Selection Guide
Analog Current Output Type Ambient Light Sensor ICs
Part Number
Output Type
Power
Supply Voltage
(V)
Sensitivity
Variation
(%)
Number of
Output Sensitivity
Switching Levels
Illuminance
Measurement Range
(lx)
Operating
Temperature Range
(°C)
Package
BH1603FVC
Current (Source)
2.4 to 5.5
±15
3 steps
0 to 100,000
-40 to +85
WSOF6
BH1620FVC
Current (Source)
2.4 to 5.5
±15
3 steps
0 to 100,000
-40 to +85
WSOF5
BH1603FVC
BH1620FVC
Digital 16-bit Serial Output Type Ambient Light Sensor ICs
Part Number
Output Type
Power
Supply Voltage
(V)
Sensitivity
Variation
(%)
I/O Voltage
Illuminance
Measurement Range
(lx)
Operating
Temperature Range
(°C)
Package
BH1715FVC
I2C I/F
2.6 to 3.6
±15
1.65 to Vcc
0 to 65,000
-40 to +85
WSOF6
2
BH1721FVC
I C I/F
2.4 to 3.6
±15
1.65 to Vcc
0 to 65,000
-40 to +85
WSOF5
BH1750FVI
I2C I/F
2.4 to 3.6
±20
1.65 to Vcc
0 to 65,000
-40 to +85
WSOF6I
BH1715FVC
BH1721FVC
BH1750FVI
Key
Analog output
Serial output
High-accuracy detection
Supply voltage 2.4V~3.6V/5.5V
Output current source type
Compatible with 1.8V systems
Transparent package type
OμA standby current
Compact surface-mount package
Supports I2C bus I/F
Gain switching
Wide dynamic range
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Built-in 16-bit AD converter
Spectral sensitivity close to
the human eye
Wide operating temperature range:
-40C to +85C
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NOTE: For the most current product information, contact a ROHM sales representative in your area.
ROHM assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and
makes no representations that the circuits are free from patent infringement. Specifications subject to change without notice for the purpose
of improvement.
The products listed in this catalog are designed to be used with ordinary electronic equipment or devices (such as audio visual equipment,
office-automation equipment, communications devices, electrical appliances and electronic toys). Should you intend to use these products
with equipment or devices which require an extremely high level of reliability and the malfunction of which would directly endanger human
life (such as medical instruments, transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other
safety devices), please be sure to consult with our sales representative in advance.
© 2009 ROHM Semiconductor USA, LLC. Although every effort has been made to ensure accuracy, ROHM accepts no responsibility for
errors or omissions. Specifications and product availability may be revised without notice. No part of this document represents an offer or
contract. Industry part numbers, where specified, are given as an approximate comparative guide to circuit function only. Consult ROHM
prior to use of components in safety, health or life-critical systems. All trademarks acknowledged.
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