YB1521 Datasheet, PDF (1/9 Pages) YOBON TECHNOLOGIES,INC. – High Power Step-Up DC-DC Converter & WLED Driver

YB1521
High Power Step-Up DC-DC Converter & WLED Driver
Description
The YB1521 is a step-up DC-DC converter
which operating as current source to drive
up 45 white LEDs (3S15P) in parallel /
series configuration from a 5V system rail.
Series connecting of LEDs provides
identical LED currents resulting in uniform
brightness and eliminating the need for
ballast resistors. The light intensity of these
LEDs is proportional to the current passing
through them. The YB1521 is a fixed
frequency of 1.3MHz, allowing the use of
tiny low profile inductors and capacitors to
minimize footprint and cost in space
consideration applications for cellular
phone backlighting or other hand held
equipment.
The wide input voltage range from 2.5V to
5.5V is idea for portable applications with
higher conversion efficiency. To control
LED brightness, the LED current can be
pulsed by applying a PWM signal with a
frequency which is typically 50 KHz to the
EN pin.
Features
2.5V to 5.5V Input Voltage Range
Built In Power MOSFET
Drive Up to 15V @400mA at 5V Vin
Less than 1µA Shutdown Current
Up to 94% efficiency
Over Voltage Protection@18V
UVLO, Thermal Shutdown
Internal 1.6A Current Limit
200mv Low Reference Voltage
Built In Soft Start
PWM Dimming
SOT23-5 Package
Green Package (RoHS) Available
Applications
Cellular and Smart Phones
Handheld Computers and PDAs
Small LCD Displays
GPS Terminals
MP3 Players
Digital Still and Video Cameras
Electronic Books
Typical Application Circuit
VI = 4.5~5.5V
4.7u/1 V
I
E
O
GN
L1
6 .8u
D1
Schottk
4.7u/2 V
S
YB1521
F
15 strings
…
R1
Figure 1: Typical Application Circuit
100
90
80
70
60
50
4
Efficiency vs. Input Voltage
I_OUT =100mA
L=10μH
I_OUT =180mA
4.5
5
5.5
6
INPUT VOLTAGE (V)
Figure 2: Efficiency
YB1521 MRev.1.1
www.yobon.com.tw
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