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MX841BETR

P1-P3P4-P6
Preliminar
y
IXYS
MX841 1 03/10/05
Drawing No. 17023 www.ixys.net
MX841
White LED Ste
p
-U
p
Converte
r
Features:
• 1.1V to 5.5V Input Range
• 2 Amp Peak Switch Current
• High Efficiency > 80%
• 20V Maximum Output with Over-Voltage
Protection
• LED Intensity Control
• 1.0 MHz Fixed Frequency Switching
• 8 Lead SOIC Package
Applications:
• White LED Display Backlighting
- Low Voltage: Mobile Phones, PDA’s,
MP3 Players, Digital Cameras
- High Drive Current: Vehicle
Instrumentation Panels
Ordering Information
Part No. Description
Qty
17000-00TU SOIC-8 Standard Tube 100
17000-00TR SOIC-8 Standard T&R 2500
17043-00TU SOIC-8 Exposed Pad Tube 100
17043-00TR SOIC-8 Exposed Pad T&R 2500
General Description
The MX841 is a fixed frequency, constant current
source step-up DC/DC converter. The output current
is directly regulated making the MX841 ideal for
driving series connected white light emitting diodes
(LED’s) in backlight applications. The MX841
powers up to 3 series white LED’s at 1.1V, and 20
series/parallel white LED’s at 5.0V.
The MX841 features a 1.0MHz switching frequency
to accommodate the use of small capacitors and a
small inductor necessary in size sensitive portable
applications. Light intensity and shutdown are
conveniently controlled by a single analog voltage.
Power efficiency and battery life are extended
through the use of a high voltage, low R
DSON
N-
channel MOSFET switch.
The MX841 is designed to operate over a
temperature range of -40°C to +85°C, and is
available in an SOIC-8 Package, with or without an
Exposed Pad in Tube or on Tape and Reel.
(Alternate package types available upon request).
Functional Block Diagram Typical Application
MX841
CTRL
Vbattery
VDD
SW
OVD
Isense
CTL/
SLEEP
Rsense
Vboost
Analog
GND
Switch
GND
SW
3
145
6
87
2
osc
err amp/
comparator
sleep det bias gen
VDD
driver
Isense
OVD
band gap
+
compare
Gnd
Switch
SW
SW
CTL/SLEEP
Analog
Gnd
MX841
IXYS
Absolute Maximum Ratings (Voltages with respect to GND=0V)
Parameter Min Max Unit
V
DD
Supply Voltage -0.4 +6.5 V
CTRL Voltage G
ND
-0.4 V
DD
+0.4 V
I
SENSE
Voltage G
ND
-0.4 V
DD
+0.4 V
SW Voltage -0.4 +24.0 V
OVD Voltage -0.4 +24.0 V
Operating Ambient Temperature Range -40 +85 C
o
Storage Temperature Range -55 +150 C
o
Operating Junction Temperature Range -40 +125 C
o
Standard SOIC θ
JA
= 114°C/W
775 mW
Power Dissipation
T
A
= 27°C
Exposed Pad SOIC θ
JA
= 50°C/W
1.75 W
ESD Warning
ESD (electrostatic discharge) sensitive device. Although the MX841 features proprietary ESD protection circuitry,
permanent damage may be sustained if subjected to high energy electrostatic discharges. Proper ESD precautions
are recommended to avoid performance degradation or loss of functionality.
DC Electrical Characteristics
V
DD
=3.0V, R
SENSE
=5Ω, V
CTRL
=1.0V, L=6.8µH, C
BYP
=1µF, T
A
= -40
o
C to +85
o
C, Typical Values at +25
o
C
Unless otherwise specified
Parameter Condition Min Typ Max Unit
Supply Voltage
T
A
= 25
o
C
1.1 5.5 V
Supply Current Overvoltage
Not Switching: V
CTRL
= 260mV
V
RSENSE
> 13 X V
CTRL
0.5 0.8
Supply Current Operating Switching: V
CTRL
= V
DD,
V
RSENSE
=GND 2
mA
T
A
= +25
o
C 6 µA
Sleep Current V
CTRL
< 100mV
T
A
= +85
o
C 7 µA
CTRL Bias Current -10 µA
I
SENSE
Bias Current -7 µA
V
CTRL
>260mV 20 µA
OVD Bias Current OVD
= 18V
V
CTRL
= GND 0
OVD
Rising 22 V
Over Voltage Threshold
OVD Falling 18.5 V
CTRL / V
RSENSE
13 V/V
V
CTRL
Rising 260 mV
V
CTRL
Sleep Mode
V
CTRL
Falling 100 mV
V
SW
= 0.1V 1.9 Ω
SW On Resistance
V
SW
= 0.5V 2.2 Ω
V
DD
=1.2V, L=33µH
30 mA
Switch Current
V
DD
=5.5V, L=2.5µH
2 A
SW Voltage Range
V
DD
-
V
SCHOTTKY
20 V
T
A
= +25
o
C 0.1 µA
SW Leakage Current OVD
= V
SW
= 18V
T
A
= +85
o
C 0.3 µA
V
CTRL
0 V
DD
V
Absolute Maximum Ratings are
stress ratings. Stresses in excess of
these ratings can cause permanent
damage to the device. Functional
operation of the device at these or
any other conditions beyond those
indicated in the operational sections
of this data sheet is not implied.
Exposure of the device to the
absolute maximum ratings for an
extended period may degrade the
device and affect its reliability.
Preliminar
y
MX841 2 03/10/05
Drawing No. 17023 www.ixys.net
MX841
IXYS
AC Electrical Characteristics
V
DD
=3.0V, R
SENSE
=5Ω; V
CTRL
=1.0V, L=6.8µH; C
BYP
=1µF, T
A
= -40
o
C to +85
o
C, Typical Values at +25
o
C
Unless otherwise specified
Parameter Condition Min Typ Max Unit
Oscillator Frequency 0.6 1.0 1.3 MHz
Duty Cycle 72.5 %
Pin Description
Pin No. Pin Name Description
1, 4 SW
Power Switch. Connects the drain of the internal high voltage N-channel
MOSFET to the Inductor and Schottky Diode to generate the LED boost
voltage. This voltage is determined by the total forward bias voltage of the
LED series string and the Isense resistor value. (Note: Both pins must be
connected.)
2 Analog GND Analog Ground (Note: Must be connected to a low noise ground source.)
3 Switch GND Switch Ground (Note: Must be connected to a high current ground source.)
5 VDD
Input supply pin. Input range from 1.1 to 5.5 volts. Must be bypassed with a
low ESR capacitor to GND.
6 OVD
Over Voltage Detect input. Compares the LED boots voltage to the internal
voltage reference. If the boost voltage rises above 22V the OVD circuit
disables the oscillator and N-channel MOSFET until the boost voltage falls
below 18.5V. Must be bypassed with a low ESR capacitor to GND.
7 CTRL
Shutdown and Intensity Control Input. A control voltage above 260mV
enables device operation. A control voltage below 100mV disables device
operation. LED intensity is linearly adjusted with voltages between 260mV
and V
DD
.
8 Isense
Current Sense Input. The LED bias current is set by connecting a carbon
composite or monolithic resistor from this input to Ground. I
SENSE
regulates
this current to 1/13
of the CTRL input voltage.
Preliminar
y
MX841 3 03/10/05
Drawing No. 17023 www.ixys.net
P1-P3P4-P6

MX841BETR

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Description:
IC LED DRIVER REGULATOR 2A 8SOIC
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