Preliminary Datasheet
High Performance, Constant Current Switching
Regulator For 10PCS White LED In Series
General Description
The LP3311 is a 1.3MHz PWM boost switching
regulator designed for constant- current white LED
driver applications. The LP3311 can drive a string of
up to 10 white LEDs in series, ensuring uniform
brightness and eliminating several ballast resistors.
The LP3311 implements a constant frequency
1.3MHz PWM control scheme. The high frequency
PWM operation also saves board space by reducing
external component sizes. To improve efficiency, the
feedback voltage is set to 195 mV and 300mV,
which reduces the power dissipation in the current
setting resistor. Highly integration and internal
compensation network minimizes as 5 external
component counts. Optimized operation frequency
can meet the requirement of small LC filters value
and low operation current with high efficiency.
LP3311
Features
High Efficiency: 90%
1.3MHzFixed-Frequency PWM Operation
Maximum Output Voltage up to 40V
Operating Range : 2.7V to 5.5V
Shutdown Supply Current:<1uA
Available in SOT23-6 Package
Built-in 40V Over Voltage Protection
Minimize the External Component
RoHS Compliant and 100% Lead (Pb)-Free
Applications
WLED Backlight driver
OLED Backlight driver
PDA
MID/PTV
Ordering Information
LP3311
-
OVP Voltage
029:29V
042:42V
F: Pb-Free
Package:
B6: SOT23-6
FB Voltage
Default: VFB=200mV
A: VFB=300mV
Typical Application Circuit
Vin
4.7uH
1
Cin
10uF
6
Cout
1uF
5
Vin
EN
GND
PWM
4
LX
OVP
FB
3
2
LP3311
R1
10
Pin Configurations
Marking information
Please view website
.
(SOT23-6)
LP3311 – 00 Version 1.0 Datasheet
Feb.-2011
www.lowpowersemi.com
Page 1 of 8
Preliminary Datasheet
Functional pin description
SOT-23-6
1
2
3
Pin Name
SW
GND
FB
Pin Function
LP3311
Switch Pin. Connect this Pin to inductor and catch diode. Minimize the track
area to reduce EMI.
Ground Pin
Feedback Reference Voltage Pin. Series connect a resistor between WLED
and ground as a current sense. Sense the current feedback voltage to set the
current rating.
Chip Enable (Active High). Voltage sensing input to trigger the function of
over voltage protection. Note that this pin is high impedance. There should
be a pull low 100kΩ resistor connected to GND when the control signal is
floating.
Over voltage pin.
Supply Input Voltage Pin. Bypass 1uF capacitor to GND to reduce the input
noise.
4
EN
5
6
OVP
Vin
Function Block Diagram
LP3311 – 00 Version 1.0 Datasheet
Feb.-2011
www.lowpowersemi.com
Page 2 of 8
Preliminary Datasheet
Absolute Maximum Ratings
LP3311
Supply Input Voltage---------------------------------------------------------------------------------------------------−0.3V to 6.0V
SW Input Voltage --------------------------------------------------------------------------------------------------------−0.3V to 43V
The Other Pins ----------------------------------------------------------------------------------------------------------−0.3V to 5.5V
Power Dissipation, P
D
@ T
A
= 25°C TSOT-23-5/6-----------------------------------------------------------------------0.455W
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------- 260°C
Operation Temperature Range ---------------------------------------------------------------------------------
−
40°C to 80°C
Storage Temperature Range ----------------------------------------------------------------------------------------
−
65°C to 150°C
Electrical Characteristics
Parameter
System Supply Input
Operation voltage Range
Under Voltage Lock Out
Supply Current
Shut Down Current
Line Regulation
Oscillator
Operation Frequency
Maximum Duty Cycle
Feedback Voltage
LP3311
LP3311A
MOSFET
On Resistance of MOSFET
SW Current Limit
Protection
OVP Threshold
V
OVP
R
DS(ON)
ILM
0.5
1.4
Ω
A
F
OSC
V
DD
V
DD
I
DD
I
DD
FB=0.2V, Switch
V
EN
< 0.4V
V
IN
: 3.0~4.3V
2.7
6
2.4
430
0.1
2
1.3
V
V
uA
uA
%
MHz
%
200
300
215
315
mV
mV
Symbol
Test Condition
Min
Typ.
Max
Units
2.2
2.6
550
1
1.0
93
185
285
1.5
LP3311B6F-042
LP3311B6F-029
42
29
5
V
V
μA
V
OVP Sink Current
Shut Down Voltage
Enable on Voltage
Minimum EN Dimming
Threshold
Minimum EN Dimming
Threshold
V
EN
V
EN
VFB=0 V
VFB=200mV
0.4
0.6
0.7
1.4
V
V
V
LP3311 – 00 Version 1.0 Datasheet
Feb.-2011
www.lowpowersemi.com
Page 3 of 8
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