Preliminary Datasheet
High Performance, Constant Current Switching
Regulator For 39PCS White LED Driver
General Description
The LP3385 is a 1.2MHz PWM boost switching
regulator designed for constant- current white LED
driver applications. The LP3385 can drive a string of
up to 10 white LEDs in series, ensuring uniform
brightness and eliminating several ballast resistors.
The LP3385 implements a constant frequency
1.2MHz 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 300 mV, 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.
LP3385
Features
High Efficiency: 92%
1.2MHzFixed-Frequency PWM Operation
Maximum Output Voltage up to 36V
Operating Range : 2.7V to 6V
Shutdown Supply Current:<1uA
Available in SOT23-6 Package
Built-in 36V 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
LP3385
F: Pb-Free
Package:
B6: SOT23-6
Typical Application Circuit
Vin
Cin
10uF
22uH
1
U80
6
Cout
1uF
5
Vin
EN
GND
PWM
4
LX
OVP
FB
3
Pin Configurations
VFB=300mV
R1
15
Marking information
Part Number
LP3385B6F
Top Marking
F8
Package
SOT23-6
Other Information please view website:
www.lowpowersemi.com.
(SOT23-6)
LP3385 – 00 Version 1.0 Datasheet
FEB.-2012
www.lowpowersemi.com
2
LP3385
Page 1 of 9
Preliminary Datasheet
Functional pin description
SOT-23-6
1
2
3
Pin Name
LX
GND
FB
Pin Function
LP3385
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
LP3385 – 00 Version 1.0 Datasheet
FEB.-2012
www.lowpowersemi.com
Page 2 of 9
Preliminary Datasheet
Absolute Maximum Ratings
LP3385
Supply Input Voltage---------------------------------------------------------------------------------------------------−0.3V to 6.0V
SW Input Voltage ---------------------------------------------------------------------------------------------------------−0.3V to 45V
The Other Pins -----------------------------------------------------------------------------------------------------------−0.3V to 5.5V
Power Dissipation, P
D
@ T
A
= 25°C SOT-23-6----------------------------------------------------------------------------0.455W
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------------- 280°C
Operation Temperature Range ------------------------------------------------------------------------------
Storage Temperature Range -----------------------------------------------------------------------------------
−
40°C to 80°C
−
65°C to 150°C
4KV
200V
ESD Susceptibility
HBM(Human Body Mode) ----------------------------------------------------------------------------------------
MM((Machine Mode)) --------------------------------------------------------------------------------------------
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
MOSFET
On Resistance of MOSFET
SW Current Limit
Protection
OVP Threshold
OVP Sink Current
Shut Down Voltage
Enable on Voltage
Minimum EN Dimming
Threshold
Minimum EN Dimming
Threshold
PWM EN Dimming range
V
EN
V
EN
VFB=0 V
VFB=300mV
100
V
OVP
36
5
V
μA
V
R
DS(ON)
ILM
0.2
2
Ω
A
LP3385
F
OSC
93
285
300
315
1.2
MHz
%
mV
V
DD
V
DD
I
DD
I
DD
FB=0.2V, Switch
V
EN
< 0.4V
V
IN
: 3.0~4.3V
2.7
2.4
90
0.1
2
1
6
V
V
uA
uA
%
Symbol
Test Condition
Min
Typ.
Max
Units
0.4
0.7
0.7
1.4
500K
V
V
V
Hz
LP3385 – 00 Version 1.0 Datasheet
FEB.-2012
www.lowpowersemi.com
Page 4 of 9
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