LX1977 Datasheet, PDF (1/23 Pages) Microsemi Corporation – SMBus Ambient Light Sensor

LX1977
®
SMBus Ambient Light Sensor
TM
PRODUCTION DATASHEET
DESCRIPTION
The LX1977 is a CMOS based Ambient
Light Sensor (ALS) with an I²C compatible
SMBus interface.
This device is ideal for controlling
display back lighting systems of low cost
consumer products such as TV, portable
computers, handheld devices, or medical
devices. The LX1977 is optimized for a
linear, accurate, and very repeatable input
and output transfer function. The device also
features adjustable input range and gain.
The LX1977 has a spectral response
that emulates the human eye. Specially
designed circuitry produces peak spectral
response at 555 nm, with IR response less
than 10% above 810 nm.
Input dynamic range of this device is
adjustable via SMBus command. It can be set
to either 0 ~ 500 lux, 0 ~ 1000 lux, 0 ~ 2500
lux or 0 ~ 5000 lux.
ALS internal compensation ensures
photodiode dark current are at very low
levels, providing high output accuracy at low
ambient light levels.
The LX1977 integrates a 12-bit Sigma-
Delta A/D converter that converts the ALS
photodiode output into a digital word. This
value is read via the I²C compatible SMBus
interface.
The LX1977 ALS is internally optimized
to an accuracy of approximately 5% over
temperature. The high accuracy and
repeatability of this device eliminates the
need of calibration during product
production, which results in reduced
assembly time and lower production cost.
The LX1977 is available in an 8-pin
MSOP package, and is operational over the
ambient temperature range -40˚C to 85˚C.
KEY FEATURES
ƒ Human Eye Spectral Response
ƒ Very Low IR Sensitivity
ƒ 12-bit Resolution
ƒ 5% Typical Accuracy
ƒ Rejection to 50/60Hz
Interference
ƒ Programmable Integration Time
ƒ Programmable Interrupt Pin
ƒ I²C compatible SMBus Interface
ƒ Easy Processor Interface
ƒ No Optical Filter Needed
APPLICATIONS
ƒ Backlight Control for Notebook
ƒ Backlight Control for TV
ƒ Handheld Devices
ƒ Medical Devices
Note: I²C is a trade mark of Philips
PACKAGE ORDER INFO
T_A (°C) ^DU
3 x 5 Glass Top MSOP 8-pin
RoHS Compliant / Pb-free
-40 to 85
LX1977IDU
Note: Available in Tape & Reel. Append the letters “TR” to the part number.
(i.e. LX1977IDU -TR)
THERMAL DATA
θ_JA = 152 °C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT
Junction Temperature Calculation: T_J = T_A + (P_D x θ_JA).
The θ_JA numbers are guidelines for the thermal performance of the
device/pc-board system. All of the above assume no ambient airflow.
ABSOLUTE MAXIMUM RATINGS
V_DD ............................................................................................................... -0.3 to 6V DC
Input Voltage to All Input Pins ........................................................... -0.3V to V_DD + 0.3V
SMBus Pin Voltage (SCL, SDA) .................................................................. -0.3V to 5.5V
SMBus Pin Current (SCL, SDA) ........................................................................... < 10 mA
Operating Temperature Range ........................................................................ -40 to +85°C
Storage Temperature Range.............................................................................-40 to 100°C
RoHS / Pb-free Peak Package Solder Reflow Temperature
(40 seconds maximum exposure).................................................................... 260° (+0, -5)
PACKAGE PIN OUT
Notes: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
GLASS TOP MSOP 8 PIN
(Top View)
RoHS / Pb-free 100% Matte Tin
Copyright © 2010
Rev. 1.0, 2010-03-25
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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