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YB1518
Step-up DC-DC Converter White LED Driver
Description
Features
The YB1518 is a step-up DC-DC converter;
operates as current source to drive up to 6
white LEDs(VIN at 3.0V) or 8 LEDs(VIN at
3.4V) or 9 LEDs(VIN at 3.4V) in series.
Series connecting of the 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 YB1518 switches at a
fixed frequency of ~1MHz, 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 YB1518 can drive up to 9 white LEDs
from a single Li-Ion battery. The wide input
voltage range from 2.7V to 16V is ideal for
portable and automotive (5V/12V)
applications with higher conversion
efficiency. To control LED brightness, the
LED current can be pulsed by applying a
PWM (pulse width modulated) signal with a
frequency range of 100Hz to 1KHz to the
CTRL pin.
YB1518 has integrated Latched Over
Voltage Protection that prevents damage to
the device in case of a high impedance
output due to faulty LED or open circuit
caused by abnormal conditions.
„ Built-in internal switch
„ 2.7V to 16V input range
„ <1uA shutdown current
„ High efficiency
„ Internal Soft Start
„ Drives up to 9 white LEDs(VIN at 3.4V)
„ Over voltage protection 36V
„ Small 5-Lead SOT-23 package
„ 100mV Low Reference Voltage
Applications
„ LCD Display Module
„ White LED Backlighting
„ PDAs, GPS terminals
„ Digital Cameras
„ Cellular Phone
„ Electronic Books
„ Portable Applications
Typical Application Circuit
YB1518 MRev.1.2
Figure 1: Typical Application Circuit
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Pin Configuration
YB1518
Step-up DC-DC Converter White LED Driver
Pin Description
Table 1
Pin NAME
1 SW
2 GND
3 FB
4 CTRL
5 VIN
Figure 2: YB1518 Pin Configuration
Description
Switching Pin. This is the collector of the internal NPN power
switch. Connect to inductor and diode. Minimize the metal
trace area connected to this pin to reduce EMI.
Ground Pin. Connect directly to local ground plane.
Feedback Pin. Reference voltage is 100mV. Connect LEDs
and a resistor at this pin. LED current is determined by the
resistance and CTRL voltage.
Shutdown Pin and Dimming Control pin.
VCTRL > 1.8V generates full-scale LED current
VCTRL < 0.4V chip is off
Switching from 0.4V to 2.0V, 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
Table 2
Order Number
YB1518ST25
Supplied as
3000 units Tape & Reel
YB1518 MRev.1.2
www.yobon.com.tw
Package Marking
Y58M
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YB1518
Step-up DC-DC Converter White LED Driver
Absolute Maximum Ratings
Recommended Operating Conditions
VIN .........................................................................20V
SW Voltage ............................................................36V
FB Voltage ...............................................................5V
CTRL Voltage...........................................................5V
Maximum Junction Temp,TJ .............................150°C
Lead Temperature (Slokering 10 sec) ................300°C
Thermal Resistance............................................195°C
Operating Temperature ............................ -40°C~85°C
Supply Voltage............................................ 2.7 V~16V
SW Voltage ............................................................32V
Electricity Characteristics
(TA=25°C, Vin=3.3V, Cin=1uF Cout=10uF unless otherwise noted) Table 3
Symbol
Vin
IQ (Quiescent
Current)
VFB
ICL
IB
FRSW
DTMX
DTMN
VSAT
ILKG
VCTL
ICTL
OVP
θJA
Function Parameter
Input Voltage Range
Not Switching
Shutdown
Feedback Voltage
Switch Current Limit
FB Pin Bias Current
Switching Frequency
Maximum Duty Cycle
Minimum Duty Cycle
Switch Vcesat
Switch Leakage
Current
VCTRL for Full LED
Current
CTRL Pin Bias Current
Over Voltage
Protection
Thermal Resistance
Test Conditions
VFB = 0.3V
CTRL = 0V
Iout=20mA,Vout=12.5V
Circuit of Figure 1
100% duty cycle
40% duty cycle
VFB=100mV
At Isw = 200mA
Ctrl = 0.3V
Full On
Full Off
Ctrl = 2V
Min
2.7
1.2
90
400
900
20
Typ
1.5
0.3
100
450
350
930
Max
16
1.7
1
110
1
960
85
25
180
Units
V
mA
uA
mV
mA
mA
uA
KHz
%
%
mV
1 μA
1.7
40
34
220
V
0.3 V
μA
V
°C/W
Note:
Absolute maximum ratings are limits beyond which damage to the device may occur.
The maximum allowable power dissipation is a function of maximum function temperature , TJ(max), the
junction to ambient thermal resistance, θJA , and the ambient temperature. The maximum allowable, power
dissipation at any ambient temperature is calculated using: PD(MAX)= [TJ(max)-TA]/θJA . Exceeding the
maximum allowable power dissipation will cause excessive die temperature. All limits at temperature
extremes are guaranteed via correlation using standard statistical methods
YB1518 MRev.1.2
www.yobon.com.tw
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