L5101L-AG6-R [UTC]
WHITE LED STEP-UP CONVERTER; 白光LED升压转换器
| 型号： | L5101L-AG6-R |
| 厂家： | 
Unisonic Technologies |
| 描述： | WHITE LED STEP-UP CONVERTER |
| 文件： | 总9页 (文件大小：135K) |
| 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
ꢀ
DESCRIPTION
5
6
The UTC L5101 is a fixed frequency step-up PWM DC/DC
converter and designed for white LEDS driving with a constant
current to provide backlight in handheld devices. The device
switches at a high frequency 1.2MHz by an internal N-channel
MOSFET switch to be capable of minimum external components
using.
3
2
1
The UTC L5101 can drive up to 5 LEDs in series by a Li-Ion cell.
Series connection of LEDS provides identical LED currents
resulting in uniform brightness without ballast resistors. The low
95mV feedback voltage minimizes power loss in the current setting
resistor can have better efficiency.
SOT-26
*Pb-free plating product number: L5101L
ꢀ
FEATURES
* Built-In Open Circuit Protection
* Built-In Over Voltage Protection
* High Efficiency(Up to 84% at VIN=4.2V, 3 LEDs, ILED=20mA)
* 1.2MHz fixed switching frequency
* Low supply current: 70µA
* Matches LED current
* Requires tiny inductor and capacitors
ꢀ ORDERING INFORMATION
Order Number
Package
SOT-26
Packing
Normal
Lead Free Plating
L5101L-AG6-R
L5101-AG6-R
Tape Reel
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Copyright © 2005 Unisonic Technologies Co., Ltd
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L5101
LINEAR INTEGRATED CIRCUIT
ꢀ
PIN CONFIGURATION
VIN
5
OVP
6
SW
4
1
3
2
GND
FB
SHDN
ꢀ
PIN DESCRIPTIONS
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.
The internal MOSFET will turn off when VOUT >27V.
Overvoltage protection
OVP
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L5101
LINEAR INTEGRATED CIRCUIT
ꢀ
BLOCK DIAGRAM
Over Voltage
Comparator
SHDN
PWM/PFM
+
-
27V
Control
OVP
VIN
SW
Control
Logic
95mV
VREF
M1
Driver
+
-
PWM
Comparator
Error
AMP
+
-
FB
1.2MHz
Oscillator
Slope
RC
CC
Compensation
+
-
RS
Internal
GND
Current AMP.
Soft Start
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L5101
LINEAR INTEGRATED CIRCUIT
ꢀ
ABSOLUTE MAXIMUM RATINGS
PARAMETER
SYMBOL
VIN
RATINGS
UNIT
V
Input Voltage
SW Voltage
6
VSW
33
V
FB Voltage
VFB
6
6
V
SHDN Voltage
OVP Voltage
Junction Temperature
VSHDN
VOVP
TJ
V
34
V
+125
0 ~ +70
-40 ~ +150
℃
℃
℃
Operating Temperature Range
Storage Temperature Range
TOPR
TSTG
Note 1. 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.
2. The device is guaranteed to meet performance specification within 0℃ ~ +70℃ operating temperature range
and assured by design from –20℃ ~ +85℃.
ꢀ
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
1
mA
Supply Current
IIN
Non switching
VSHDN=0V
70
0.1
100
1.0
µA
ERROR AMPLIFIER
Feedback Voltage
FB Input Bias Current
OSCILLATOR
VFB
IFB
85
95
1
105
1.6
mV
nA
VFB=95mV
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
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TEST CIRCUIT
L1
10μH
D1
VIN
C2
0.22μF
C1
1μF
RB521S-30
VIN
SW
OVP
FB
SHDN
GND
ILED
L5101
RFB
4.7Ω
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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 capacitors (1µF input with 1µF output ) are sufficient, X5R
and X7R types are recommended
ꢁ
Diode Selection: An Schottky diode rated at 100mA ~ 200mA is sufficient for most applications.
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
L
D1
10μH
VIN
C1
1μF
C2
1μF
RB521S-30
VIN
SW
OVP
FB
SHDN
GND
L5101
RFB
4.7Ω
Fig.1 Dimming Control with a PWM Signal
Open-Circuit Protection
When a high output voltage exceeds maximum 33V, the built-in OVP (Over Voltage Protection) will be triggered to
prevent the damage resulting from an open circuit condition.
Dimming Control
There are three different ways of dimming control circuits as follows:
1. Using a PWM signal
L
D1
10μH
VIN
C1
1μF
RB521S-30
VIN
SW
OVP
FB
SHDN
GND
PWM
L5101
R2
R1
RFB
4.7Ω
51KΩ
1KΩ
Fig.2 Dimming Control Using a PWM Signal
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L5101
LINEAR INTEGRATED CIRCUIT
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APPLICATION INFORMATION(Cont.)
2. Using a DC Voltage
L
D1
10μH
VIN
C2
C1
RB521S-30
1μF
1μF
VIN
SW
OVP
FB
SHDN
GND
VDC
0~5V
L5101
R2
51KΩ
R1
1KΩ
RFB
4.7Ω
Fig.3 Dimming Control Using a DC Voltage
3. Using a Filtered PWM Signal
VIN
L
D1
10μH
C2
1μF
C1
1μF
RB521S-30
VIN
SW
OVP
FB
SHDN
GND
R1
1KΩ
L5101
R3
R2
RFB
4.7Ω
5.1KΩ
51KΩ
PWM
C3
0.1μF
Fig.4 Dimming Control Using a Filter PWM Signal
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L5101
LINEAR INTEGRATED CIRCUIT
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TYPICAL CHARACTERISTICS
Supply Current vs. Supply Voltage(V)
Supply Current vs. Supply Voltage(V)
70
1.6
FB=GND
1.4
1.2
1.0
60
50
40
30
FB=VIN
0.8
0.6
Non-Switching
5
Switching
5
2
3
4
6
2
3
4
6
Supply Voltage(V)
Supply Voltage(V)
RDS-ON vs. Supply Voltage (V)
3 LEDs Efficiency vs. LED Current
1.4
90
V = 4.2V
IN
1.3
1.2
1.1
1.0
0.9
0.8
85
80
75
70
65
60
V = 3.6V
IN
V = 3.0V
IN
3 LEDs, 6.8μH
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0
5
10
LED Current (mA)
15
20
Supply Voltage (V)
3 LEDs Efficiency vs. LED Current
VIN = 4.2V
4 LEDs Efficiency vs. LED Current
VIN = 4.2V
90
85
80
75
70
65
60
90
85
80
75
70
65
60
VIN = 3.0V
VIN = 3.6V
VIN = 3.6V
VIN = 3.0V
3 LEDs, 10μH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
4 LEDs, 10μH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
0
5
10
LED Current(mA)
15
20
0
5
10
15
20
LED Current (mA)
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L5101
LINEAR INTEGRATED CIRCUIT
ꢀ
TYPICAL CHARACTERISTICS(cont.)
5 LEDs Efficiency vs. LED Current
90
V = 4.2V
IN
85
80
75
70
65
60
V = 3.6V
IN
V = 3.0V
IN
5 LEDs, 10μH
L1: 976AS-100M, TOKO
D1: RB521S-30, ROHM
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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