Richtek RT9269GE, RT9269PE Schematic [ru]
RT9269
Tiny Package, High Efficiency, Constant Current LED Driver
General Description
The RT9269 is a compact, high efficient LED driver with
high flexibility of application conf igurations in charge pump
mode or in boost rectifier mode, delivering Tens of mA
constant output current f or driving 1~4 white LED's.
The 0.25V low reference voltage minimized the power loss
across the current-setting resistor .
The wide applica ble V DD ra nge makes R T9269 suitable for
1 to 4 battery cell applications as well as being supplied
with 2.5/3.3/5/6V system powers. The 500kHz high
switching rate minimized the size of external components.
Besides, the 17μA low quiescent current together with high
efficiency maintains long battery lifetime.
The output current is set with 1 external resistor . And the
chip enable (EN) pin can be used for tuning the LED
brightness by controlling the ON/OFF duty with external
clock. RT9269 is provided in SOT -23-6 pa ckage.
Ordering Information
RT9269
Package Type
E : SOT-23-6
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
` RoHS compliant and compatible with the current require ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Features
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0.25V Low Reference Voltage
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μμ
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z 17
μA Quiescent (Switch-off) Supply Current
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μμ
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z Zero Shutdown Mode Supply Current
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z 85% Efficiency
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z 500kHz Fixed Switching Rate
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z T uning LED brightness with EN Pin ON/OFF Duty
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z Small SOT-23-6 Package
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z RoHS Compliant and 100% Lead (Pb)-Free
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Applications
z LED Module
z Hand Held Pa nel
z Compact Ba ck Light Module
z Small Battery Charger
z Constant Current Source
Pin Configurations
(TOP VIEW)
FB
VDD LX
4
56
23
EXT
GND
EN
SOT-23-6
Marking Information
For marking information, conta ct our sales representative
directly or through a Richtek distributor located in your
area.
DS9269-12 April 2011 www.richtek.com
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RT9269
T ypical Application Circuit
V
IN
C1
1uF
To VDD
or
Duty Control
Brightness
Figure 1. RT9269 drives single or parallel LED's in charge pump configuration
V
IN
To VDD
or
Duty Control
Brightness
C1
1uF
VDD
RT9269
GND
RT9269
D1 D2
EXT
0.25V
FBEN
VDD
EXT
FBEN
GND
C2
1uF
D1 D2
C2
1uF
0.25V
C3
1uF
R1 R2
15 15
C3
1uF
R1
15
Figure 2. RT9269 drives 2 series connected LED's in charge pump configuration
V
IN
C1
1uF
To VDD
or
Duty Control
Brightness
R1
1K
VDD
RT9269
GND
C2
10uF
LX
FBEN
0.25V
L1
10uH to 100uH
Q1
C3
10uF
R2
15
Figure 3. RT9269 drives 2~4 series connected LED's in boost rectifier configuration
Note: NICHIA NSCW100 is used for RT9269 LED parts.
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DS9269-12 April 2011www.richtek.com
Functional Pin Description
RT9269
Pin No. Pin Name
1 EN
2 EXT
3 GND
4 LX
5 VDD
6 FB
Pin Function
Chip Enable (Active High)
Output Pin for Configuring Charge Pump or Driving External NMOS
Ground
Pin for Switching
Input Positive Power Pin of RT9269
Feedback Input pin Internal Reference Voltage for the Error Amplifier is 0.25V.
Function Block Diagram
VDD
FB
1.25V
VDD
RT9269
-
Loop Control Circuit
+
EXT
LX
Q1
N MOS
R1
EN
R2
Q2
N MOS
Over Temp.
Detector
Shut Down
GND
DS9269-12 April 2011 www.richtek.com
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