YOBON YB1521 Technical data
DC Converter & WLED Driver
y
EFFICIENCY (%)
D
1
Schottk
FIGN
S
E
4.7u/2V
6.8
u
=4.5~5.5V
L
1
…
4.7u/1V
O
R
1
YB1521
High Power Step-Up DC-
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
YB1521
Figure 1: Typical Application Circuit Figure 2: Efficienc
15 strings
100
90
80
70
60
50
4 4.5 5 5.5 6
Efficiency vs. Input Voltage
I
=100mA L=10μH
OUT
I
=180mA
OUT
INPUT VOLTAGE (V)
YB1521 MRev.1.1 www.yobon.com.tw 1
DC Converter & WLED Driver
High Power Step-Up DC-
Pin Configuration
Figure 3: Pin Configuration
Pin Assignment & Description
YB1521
Table1
Pin NAME Description
1 SW
2 GND Ground pin. Connect directly to local ground plane.
3 FB
4 EN
5 IN
Switching Pin. This is the drain of internal power MOSFET
switch. Connect the power inductor and output rectifier to SW.
Feedback Pin. Reference voltage is 200mV. Connect LEDs and
a resistor at this pin. LED current is determined by the
resistance and FB voltage.
Shutdown Pin and Dimming Control Pin. PWM duty cycle
controls the LED current.
Input Supply Pin. Bypass this pin with a capacitor as close to
the device as possible.
Ordering Information
Table2
Order Number Package Type
Supplied As Package Marking
YB1521ST25 SOT23-5 3000 Units Tape & Reel
YB1521 MRev.1.1 www.yobon.com.tw 2
Y521
DC Converter & WLED Driver
YB1521
High Power Step-Up DC-
Absolute Maximum Ratings (Note 1)
VIN to GND ............................ -0.3V to 6V
VEN to GND ........................... -0.3V to 6V
VSW to GND......................... -0.3V to 18V
Junction Temperature ................... 150℃
Storage Temperature .......-55℃ to 150℃
Lead Temperature......................... 300℃
ESD HBM ........................................ 3KV
ESD MM .........................................250V
Recommended Operating Conditions
Supply Voltage VIN............... 2.5V to 5.5V
Operating Temperature .......-40℃ to 85℃
Output Voltage ......................... 0V to 15V
Thermal Information (Note 3)
θJA............................................ 220℃ / W
Note:
1. Exceeding these ratings may damage the device.
2. The device is not guaranteed to function outside of its operating conditions.
3. θJA is measured in free air at TA = 25℃ on a low effective thermal conductivity board.
(Note 2)
YB1521 MRev.1.1 www.yobon.com.tw 3
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