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A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
DESCRIPTION
FEATURES
The A8241 is a CMOS based White/Blue LED

Low 60mV Dropout at 20mA
driver with stand-alone capability. The driver is

4% LED Current Matching
primarily designed for LED backlighting of LCD
display powered by Li-ion battery with its high
efficiency, low sandby current and wide range of
input supply voltage.
The A8241 is suitable for applications such as
portable device display and keypad backlighting.
In portable application, six channel LED solutions
are popular.
The A8241 is available in SOT-26 package.
ORDERING INFORMATION
Package Type
Part Number
APPLICATION

Next-Generation Wireless Handsets

PDAs, Palmtops, and Handy Terminals


Digital Cameras, Camcorders
Battery-Powered Equipment
A8241E6R
SOT-26
E6
A8241E6VR
Note
R: Tape & Reel
V: Green Package
Typical Application
AiT provides all Pb free products
Suffix “ V” means Green Package
REV1.0
-AUG 2009 RELEASED -
-1-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
PIN DESCRIPTION
Top View
Pin #
Symbol
Function
1
EN
2
GND
Ground
3
LED4
LED4 Pin. Connect to the LED cathode, leave it open or connect to GND if unused.
4
LED3
LED3 Pin. Connect to the LED cathode, leave it open or connect to GND if unused.
5
LED2
LED2 Pin. Connect to the LED cathode, leave it open or connect to GND if unused.
6
LED1
LED1 Pin. Connect to the LED cathode, leave it open or connect to GND if unused.
Enable Pin. Active high, with an internal 141kΩ pull-down resistor.
ABSOLUTE MAXIMUM RATINGS
Supply Input Voltage, VIN
−0.3V to 6V
The other pins
−0.3V to 6V
Power Dissipation, PD @ TA = 25°C SOT-23-6
0.4W
Package Thermal Resistance(Note 4) SOT-23-6, θJA
250oC/W
Lead Temperature (Soldering, 10 sec.)
Operation Temperature Range
260oC
−40°C to 85°C
Junction Temperature
Storage Temperature Range
150 oC
−40°C to 85°C
ESD Susceptibility (Note 2)
HBM (Human Body Mode)
MM (Machine Mode)
-2kV
-200V
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 or any other conditions beyond those indicated under
"recommended operating conditions" is not implied. Exposure to absolute maximum rated conditions for extended periods
may affect device reliability.
REV1.0
-AUG 2009 RELEASED -
-2-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
RECOMMENDED OPERATING CONDITIONS
Parameter
Min
Suply Voltage VDD
Typ
Max
Unit
2.7
5.5
V
-
< 5.5
V
Junction Temperature Range
-40
125
°C
Ambient Temperature Range
-40
85
°C
Other Pins (Except GND)
ELECTRICAL CHARACTERISTICS
(VIN = VEN=3.6V, TA = 25°C, Unless Otherwise specification)
Parameter
Min
Typ
Max
Unit
Suply Voltage VDD
2.7
-
5.5
V
Output Current ILED
18
20
22
mA
IOUT=200mA(NOTES5)
-
-
60
mV
Quiescent Current IQ
No Load
-
250
300
μA
Shutdown Current ISD
VEN=0V
-
0.1
1
μA
LED Current Matching
-4
-
4
Enable High Level Input Voltage VIH
2.7
-
-
V
Enable Low Level Input Voltage VIL
-
-
0.6
V
Startup Time
-
20
-
μs
300
650
900
μs
Thermal Shutdown Temperature TSD
-
145
-
oC
Hysteresis Temperature
-
20
-
oC
Dropout Voltage of any LEDx Current
Source VDO
Shutdown Delay Time TOFF
Conditions
VEN=0V
%
Note1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress
ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of
the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to
affect device reliability.
Note2. Devices are ESD sensitive. Handling precaution recommended.
Note3. The device is not guaranteed to function outside its operating conditions.
Note4. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC
51-3 thermal measurement standard.
Note5. Dropout voltage of current source is the minimum voltage needed at pin LEDx to provide the specified current.
REV1.0
-AUG 2009 RELEASED -
-3-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS
1. Efficiency vs. Supply Voltage
2. LED Current vs. Supply Voltage
3.
4.
LED Current vs. LED Dropout Voltage
REV1.0
-AUG 2009 RELEASED -
Quiescent Current vs. Supply Voltage
-4-
AiT Semiconductor Inc.
www.ait-ic.com
A8241
4CHANNEL WHITE LED DRIVER
BLOCK DIAGRAM
A8241
REV1.0
-AUG 2009 RELEASED -
-5-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
DETAILED INFORMATION
The A8241 works with a wide range of supply voltage, from 2.7V to 6.0V. The forward voltage of commercial
white/blue LED is in the range of 2.9V to 3.5V at current level of 20mA. Proper selection of the LED to match
the supply voltage can fully utilize the Li-ion battery. For example, there is 1% to 3% power left in the Li-ion
battery when its voltage reaches 3.275V. So a LED with a forward voltage value of 3.2V can use up to 99%
of the battery power under normal working condition. When the voltage of the battery drops below 3.2V, the
current through the LED (hence the brightness) starts to decrease.
Due to its uniquely designed current regulator, A8241 offer low output dropout and provide superior efficiency
performance over standard Inductive boost type and capacitive charge pump type LED driver.
The EN pin controls the ON/OFF state of the device. A high level state turns on the device and a low level
turns off the device, results in the low off state current. The pin needs to be terminated since a floating level of
the EN pin will cause the instability of the device.
The sink current has a constant value of 20mA. The brightness of the LED can be adjusted by controlling the
duty cycle of the A8241 LEDn output. This can be accomplished by applying a PWM signal to the EN pin. In
A8241, the internal power on sequence presents a delay time of 6us from CE pin to LEDn pin. Hence, In order
To normally modulate the output of LEDn in every cycle, the width of dimming signal applied CE pin have to
be no less than 6ux, For example, when a dimming signal of 20KHz is applied, the minimum range of dimming
is about 12%, that is, the average output current on each channel is 2.4mA.
REV1.0
-AUG 2009 RELEASED -
-6-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
PACKAGE INFORMATION
Dimension in SOT-26 (Unit: mm)
Tape Dimension
REV1.0
-AUG 2009 RELEASED -
Reel Dimension
-7-
A8241
AiT Semiconductor Inc.
www.ait-ic.com
4CHANNEL WHITE LED DRIVER
IMPORTANT NOTICE
AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to
discontinue any integrated circuit product or service without notice, and advises its customers to obtain the
latest version of relevant information to verify, before placing orders, that the information being relied on is
current.
AiT Semiconductor Inc.'s integrated circuit products are not designed, intended, authorized, or warranted to
be suitable for use in life support applications, devices or systems or other critical applications.
products in such applications is understood to be fully at the risk of the customer.
Use of AiT
As used herein may
involve potential risks of death, personal injury, or servere property, or environmental damage.
In order to
minimize risks associated with the customer's applications, the customer should provide adequate design and
operating safeguards.
AiT Semiconductor Inc. assumes to no liability to customer product design or application support.
AiT
warrants the performance of its products of the specifications applicable at the time of sale.
REV1.0
-AUG 2009 RELEASED -
-8-