YOBON YB1518 Technical data
YB1518
Step-up DC-DC Converter White LED Driver
Description
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.
Typical Application Circuit
Figure 1: Typical Application Circuit
Features
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
YB1518 MRev.1.2 www.yobon.com.tw 1
YB1518
Step-up DC-DC Converter White LED Driver
Pin Configuration
Figure 2: YB1518 Pin Configuration
Pin Description
Tab le 1
Pin NAME Description
1
SW
2
GND Ground Pin. Connect directly to local ground plane.
3
FB
4
CTRL
5
VIN
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.
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
Tab l e 2
Order Number Supplied as Package Marking
YB1518ST25 3000 units Tape & Reel Y58M
YB1518 MRev.1.2 www.yobon.com.tw 2
YB1518
(TA
Step-up DC-DC Converter White LED Driver
Absolute Maximum Ratings
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
Recommended Operating Conditions
Operating Temperature ............................-40°C~85°C
Supply Voltage............................................ 2.7 V~16V
SW Voltage............................................................ 32V
Electricity Characteristics
=25°C, Vin=3.3V, Cin=1uF Cout=10uF unless otherwise noted)Table 3
Symbol Function Parameter Test Conditions Min Typ Max Units
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
Vin Input Voltage Range 2.7 16 V
IQ (Quiescent
Current)
VFB Feedback Voltage
ICL Switch Current Limit
IB FB Pin Bias Current VFB=100mV 1 uA
FRSW Switching Frequency 900 930 960 KHz
DTMX Maximum Duty Cycle 85 %
DTMN Minimum Duty Cycle 20 25 %
VSAT Switch Vcesat At Isw = 200mA 180 mV
ILKG
VCTL
ICTL CTRL Pin Bias Current Ctrl = 2V 40 μA
OVP
θJA Thermal Resistance 220 °C/W
Not Switching VFB = 0.3V 1.2 1.5 1.7 mA
Shutdown CTRL = 0V 0.3 1 uA
Iout=20mA,Vout=12.5V
Circuit of Figure 1
100% duty cycle 400 450 mA
Switch Leakage
Current
VCTRL for Full LED
Current
Over Voltage
Protection
90 100 110 mV
40% duty cycle 350 mA
Ctrl = 0.3V 1 μA
Full On 1.7 V
Full Off 0.3 V
34 V
YB1518 MRev.1.2 www.yobon.com.tw 3
YB1518
Step-up DC-DC Converter White LED Driver
Typical Performance Characteristics
Condition : VIN 2.8V ; 4.4V / VCRTL : 3V
VOUT ; 2pcs white LEDs
Condition : VIN 2.8V ; 4.4V / VCTRL: 3V
VOUT ; 3pcs white LEDs
Efficiency vs Vin (2WLEDs)
82
81
Efficiency(%)
80
79
78
2.7 3.0 3.3 3.6 3.9 4.2 4.5
Vin(V)
Efficiency(%)
Efficiency vs Vin (3WLEDs)
83.0
82.5
82.0
81.5
81.0
2.7 3.0 3.3 3.6 3.9 4.2 4.5
Vin(V)
YB1518 MRev.1.2 www.yobon.com.tw 4
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