L5101G-AG6-R [UTC]
WHITE LED STEP-UP CONVERTER; 白光LED升压转换器
| 型号： | L5101G-AG6-R |
| 厂家： | 
Unisonic Technologies |
| 描述： | WHITE LED STEP-UP CONVERTER |
| 文件： | 总10页 (文件大小：254K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
UNISONIC TECHNOLOGIES CO., LTD
L5101
LINEAR INTEGRATED CIRCUIT
WHITE LED STEP-UP
CONVERTER
4
5
DESCRIPTION
6
The UTC L5101 is a constant current step-up PWM DC/DC
converter optimized to drive white LEDs. It can drive LEDs in series
with a Li-Ion cell.
3
2
1
The switching frequency of the internal NPN is up to 1.2MHz.
High frequency allows the use of tiny external components and the
current setting resistor has minimum power dissipation for the low
feedback voltage of 95mV. The built-in OVP prevents the UTC
L5101 damage from the open load condition.
Series connection of LEDs provides identical LED currents which
contributes to uniform brightness, saving the use of ballast
resistors.
SOT-26
The UTC L5101 is universally used in cellular phones, PDAs ,
DSCs, handheld devices, and white LED display backlighting.
FEATURES
* Open Circuit and Over Voltage Protection
* High Efficiency: 86% Typical
* Switching Frequency: 1.2MHz
* Supply Current is 1.0mA
* Matches LED Current
* Requires Tiny Inductor and Capacitors
* Halogen Free
ORDERING INFORMATION
Ordering Number
L5101G-AG6-R
Package
SOT-26
Packing
Tape Reel
MARKING
www.unisonic.com.tw
Copyright © 2009 Unisonic Technologies Co., Ltd
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LINEAR INTEGRATED CIRCUIT
PIN CONFIGURATION
PIN DESCRIPTION
PIN NO.
PIN NAME
Shutdown
Ground
SYMBOL
DESCRIPTION
1
2
SHDN Tie to higher than 1.5V to enable device, 0.3V or less to disable device.
GND
Reference voltage is 95mV. Connect cathode of lowest LED and
resistor here. Calculation formula: RFB=95mV/ILED
3
4
Feedback
Switch
FB
Connect inductor/diode here. Minimize trace area at this pin to reduce
EMI.
SW
5
6
Power input
VIN
Bypass VIN to GND with a capacitor sitting as close to VIN as possible.
Over voltage protection
OVP The internal NPN will turn off when VOUT >27V.
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L5101
LINEAR INTEGRATED CIRCUIT
BLOCK DIAGRAM
VIN
5
Over Voltage
Comparator
+
95mV
27V
1.25V
VREF
-
6
4
OVP
SW
PWM
Comparator
Control
Logic
Driver
-
Q1
+
Error
AMP
+
-
3
1
FB
RAMP
GENERATOR
1.2MHz
Oscillator
RC
CC
+
-
RS
SHDN
2
GND
Current AMP.
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L5101
LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATING
PARAMETER
SYMBOL
VIN
RATINGS
UNIT
V
Input Voltage
SW Voltage
FB Voltage
6
VSW
33
V
VFB
6
6
V
SHDN Voltage
VSHDN
VOVP
TJ
V
OVP Voltage
34
V
Junction Temperature
Operating Temperature Range
Storage Temperature Range
+125
℃
℃
℃
TOPR
TSTG
-20 ~ +85
-40 ~ +150
Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.
Absolute maximum ratings are stress ratings only and functional device operation is not implied.
ELECTRICAL CHARACTERISTICS (VSHDN=3V, VIN=3V, Ta=25℃, unless otherwise specified.)
PARAMETER
SYMBOL
VIN
TEST CONDITIONS
MIN
2.5
TYP
MAX UNIT
Operating Voltage
5.5
5
V
Switching
Non switching
SHDN=0V
2
1
mA
μA
Supply Current
IIN
2
V
0.1
1.0
ERROR AMPLIFIER
Feedback Voltage
FB Input Bias Current
OSCILLATOR
VFB
IFB
85
95
105
1.6
mV
nA
VFB=95mV
100
Switching Frequency
Maximum Duty Cycle
POWER SWITCH
SW ON Resistance
Switch Leakage Current
CONTROL INPUT
fSW
DC
0.8
85
1.2
90
MHz
%
RON(SW)
1.4
0.1
5
1
Ω
ILEAK (SW)) VSW=33V
μA
High
Low
VIH(SHDN) ON
VIL(SHDN) OFF
1.5
V
V
Shutdown Voltage
0.3
OVER VOLTAGE PROTECTION
OVP Input Resistance
OVP Threshold
RIN(OVP)
0.6
22
1.2
27
1.8
32
MΩ
VTHR(OVP) 1V Hysteresis typical
V
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L5101
LINEAR INTEGRATED CIRCUIT
TEST CIRCUIT
Fig.1 Test Circuit
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L5101
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION
Recommended Component Selection
* Inductor Selection: A 10μH inductor is recommended for most applications.
* Capacitor Selection: The small size of ceramic capacitor makes it ideal for UTC L5101 applications, X5R and X7R
types are recommended because of their stable characteristics, 1μF input capacitor with 1μF
output capacitor is sufficient for most UTC L5101 applications.
* Diode Selection: Schottky diode, for its low forward voltage drop and fast reverse recovery, is an ideal choice for
the UTC L5101 diode. A Schottky diode rated 100mA to 200mA is sufficient for most UTC L5101
applications, and the higher current rating usually have larger diode capacitance which can
cause significant switching losses at the 1.2MHz switching frequency.
LED Current Control
A feedback resistor (precision 1% recommended) as feedback resistor control the LED current. (RFB in Figure 1)
* Feedback reference voltage: 95mV.
* LED current is 95mV/RFB.
* The formula for RFB selection: RFB=95mV/ILED
Open-Circuit Protection
The OVP(Over Voltage Protection) protects the voltage lower than its maximum level under the open circuit
condition, which is caused by the failure or disconnection of the LEDs. The above undesired fault conditions will
cause the feedback voltage falling to 0V, then the UTC L5101 increases duty circle resulting in a high voltage in SW
pin.
Dimming Control
There are three different ways of dimming control circuits as follows:
1. Using a PWM signal
L1
10µH
D1
VIN
SW
OVP
VIN
C2
1µF
UTC L5101
GND
C1
1µF
FB
SHDN
R2
R1
1K
PWM
51K
RFB
4.7Ω
Fig. 2 Dimming Control Using a PWM Signal
Fig. 3 Dimming Control with a PWM Signal
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L5101
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
2. Using a DC Voltage
L1
10µH
D1
VIN
SW
OVP
VIN
C2
1µF
UTC L5101
GND
C1
1µF
FB
SHDN
R2
R1
1K
VDC
0~5V 51K
RFB
4.7Ω
Fig. 4 Dimming Control Using a DC Voltage
3. Using a Filtered PWM Signal
L1
10µH
D1
VIN
SW
OVP
VIN
C2
1µF
UTC L5101
GND
C1
1µF
R1
FB
SHDN
1K
R2
51K
R3
5.1K
RFB
4.7Ω
PWM
C3
0.1µF
Fig. 5 Dimming Control Using a Filter PWM Signal
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L5101
LINEAR INTEGRATED CIRCUIT
TYPICAL APPLICATION CIRCUIT
Fig. 6 Six White LEDs Application in Li-Ion Battery
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L5101
LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS
Supply Current vs. Supply Voltage
Supply Current vs. Supply Voltage
1.35
1.34
1.95
1.90
1.33
1.32
FB=VIN
Non-Switching
1.31
1.85
1.80
FB=GND
Switching
1.30
1.29
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Supply Voltage (V)
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Supply Voltage (V)
3LEDs Efficiency vs. LED Current
RDS(ON) vs. Supply Voltage
90
1.4
VIN=3.6V
85
80
VIN=3.0V
1.3
1.2
75
3LEDs,
L1=10μH
70
65
1.1
1.0
VIN=4.2V
60
55
0
5
10
15
20
2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Supply Voltage (V)
LED Current (mA)
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L5101
LINEAR INTEGRATED CIRCUIT
TYPICAL CHARACTERISTICS
4LEDs Efficiency vs. LED Current
VIN=3.6V
90
85
VIN=3.0V
80
75
4LEDs,
L1=10μH
70
65
60
VIN=4.2V
0
5
10
15
20
LED Current (mA)
UTC assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or
other parameters) listed in products specifications of any and all UTC products described or contained
herein. UTC products are not designed for use in life support appliances, devices or systems where
malfunction of these products can be reasonably expected to result in personal injury. Reproduction in
whole or in part is prohibited without the prior written consent of the copyright owner. The information
presented in this document does not form part of any quotation or contract, is believed to be accurate
and reliable and may be changed without notice.
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