LRC LR246

LESHAN RADIO COMPANY, LTD.
LR246 White LED Step-Up Converter
LR246 is a step-up DC/DC converter
specifically designed to drive white LED with a
constant current. It can drive two,three,or four
LEDS. It switches at 1.2MHz and use tiny
external components. The output capacitor can
be as small as 0.22uF,which can save space
and cost versus alternative solutions. Feedback
voltage is as low as 95mV. Built-in OverVoltage
¾
¾
¾
¾
¾
¾
¾
¾
¾
OverVoltage Function
Fast 1.2MHz Switching Frequency
Requires Only 0.22uF Output Capacitor
Inherently Matched LED Current
High Efficiency: 85% Typical
2.5V to 10V VIN ranges
Drives Up to Four series LEDs with a Li-lon cell
Uses Very Tiny Inductors
SOT-26 Package
function.
Absolute maximum ratings
Parameter
symbol
value
unit
Supply Voltage
VIN
10
V
Feedback Voltage
FB
10
V
Switch Voltage
SW
20
V
CE Voltage
VCE
10
V
Operating temperature range
Topr
-25 to +70
℃
Storage temperature range
Rstg
-55 to +150
℃
Junction temperature
Tj
125
℃
Pin name
Description
1
6
2
5
3
4
Symbol
Description
Symbol
6：Supply
1：Switch
SW
VIN
Voltage
2：GND
3：Feedback
GND
FB
5：Over
Voltage
4：Start-Up
OVP
CE
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LESHAN RADIO COMPANY, LTD.
LR246
Block Diagram
PIN1(SW)
PWM
CONTROL
PIN5(OVP)
CURRENT SENSE
+
Fosc
SLOPE COMP
+
0
0
-
PIN6(VIN) VREF
0
PIN2(GND)
+
gm
-
SHUTDOWN
+
PIN4
PIN3(FB)
D246
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LESHAN RADIO COMPANY, LTD.
LR246
Electrical Characteristics
Tamb = 25℃, VIN=3V，VCE=3V,unless otherwise specified.
Parameter
Test Conditions / Pins
Min
Minimum Operating Voltage
Type
Max
2.5
Unit
V
Maximum Operating Voltage
10
V
ISW=100mA,
Feedback Voltage
86
95
104
mV
50
100
200
nA
1.9
2.5
mA
0.1
1
uA
1.6
MHz
Duty Cycle=66%
FB Pin Bias Current
Supply Current
VCE=0V
Switching Frequency
0.8
1.2
Maximum Duty Cycle
85
90
%
OVP Protection
27
V
Switch Current Limit
320
mA
mV
Switch VCESAT
ISW =250mA
350
Switch Leakage Current
VSW=5V
0.01
CE Voltage High
5
1.5
uA
V
CE Voltage Low
0.4
CE Pin Bias Current
65
V
uA
Typical Application
L1
1
HI
2
22uH
VCC
PIN1(SW)
PWM
CONTROL
C1
D4
1
2
D1
PIN5(OVP)
CURRENT SENSE
1u
C2
0.22 u
+
Fosc
SLOPECOMP
+
D1
0
0
-
PIN6(VIN) VREF
0
PIN2(GND)
D1
+
gm
-
1k
SHUTDOWN
+
PIN4
PIN3(FB)
R1
3/8
LESHAN RADIO COMPANY, LTD.
LR246
Analog Voltage Light Control
L1
1
HI
2
22uH
VCC
PIN1(SW)
PWM
CONTROL
D4
1
2
D1
PIN5(OVP)
C1
CURRENT SENSE
1u
C2
0.22u
+
SLOPE COMP
Fosc
+
0
D1
0
-
PIN6(VIN) VREF
0
PIN2(GND)
D1
+
gm
-
5K
SHUTDOWN
R1
+
PIN4
PIN3(FB)
90K
HI
VDC
Logic Voltage Light Control
L1
1
HI
2
22uH
VCC
PIN1(SW)
PWM
CONTROL
C1
D4
1
2
D1
PIN5(OVP)
CURRENT SENSE
1u
C2
0 .22 u
+
Fosc
SLOPE COMP
+
D1
0
0
-
PIN6(VIN) VREF
0
PIN2(GND)
D1
+
gm
SHUTDOWN
R1
+
PWM
1k
-
HI
PIN4
PIN3(FB)
4/8
LESHAN RADIO COMPANY, LTD.
LR246
Figure
Iq(mA)
Iq
Vs T
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-50
100
25
0
2
4
6
8
10
Vin(V)
Swich Frequency
Vs
T
Swich Frequency（MHz）
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-25
0
25
50
75
100
T（°C）
5/8
LESHAN RADIO COMPANY, LTD.
LR246
η（%）
η VS T
84.5
84
83.5
83
82.5
82
81.5
81
80.5
80
ILED=10mA
ILED=15mA
ILED=20mA
-25
0
25
50
75
100
T（°C）
η（%）
Drive 2LED
86
84
82
80
78
76
74
72
70
Vin=3.6V
Vin=3V
0
10
20
ILED(mA)
30
40
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LESHAN RADIO COMPANY, LTD.
LR246
Drive 3LED
90
η（%）
85
80
Vin=3V
Vin=3.6V
75
70
65
60
0
5
10
ILED（mA）
15
20
7/8
LESHAN RADIO COMPANY, LTD.
SOT-26
LR246
Diagram
Symbol
A
A1
B
b
C
D
E
H
L
min
0.787
1.397
0.250
2.591
2.692
0.838
0.080
0.300
Dimension(in mm)
max
1.450
0.152
1.803
0.559
2.997
3.099
1.041
0.254
0.610
Dimension(in Inch)
min
max
0.031
0.057
0.006
0.055
0.071
0.010
0.022
0.102
0.118
0.106
0.122
0.033
0.041
0.003
0.010
0.012
0.024
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