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Richtek |
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RT8472
1A, Hysteretic, High Brightness LED Driver with Internal
Switch
General Description
The RT8472 is a high efficiency, continuous mode inductive
step-down converter, designed for driving single or multiple
series connected LEDs from a voltage source higher than
the LED voltage. It operates from an input voltage of 5V to
30V and employs hysteretic control with a high side current
sense resistor to set the constant output current.
The RT8472 includes an output switch and a high side
output current sensing circuit, which uses an external
resistor to set the nominal average output current. LED
brightness control is achieved with PWM dimming from
an analog or PWM input signal.
The RT8472 is available in a small TSOT-23-5 package.
Ordering Information
RT8472
Package Type
J5 : TSOT-23-5
Lead Plating System
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
z 5V to 30V Input Voltage Range
z Hysteretic Control with High Side Current Sensing
z Internal N-MOSFET with 350mΩ Low RDS(ON)
z 1A Output Current
z Up to 97% Efficiency
z Typical ±5% LED Current Accuracy
z Analog or PWM Control Signal for LED Dimming
z 300Hz On-Board Ramp Generator
z Input Under Voltage Lockout
z Thermal Shutdown Protection
z RoHS Compliant and Halogen Free
Applications
z Automotive LED Lighting
z High Power LED Lighting
z Indicator and Emergency Lighting
z Architectural Lighting
z Low Voltage Industrial Lighting
z Signage and Decorative LED Lighting
Pin Configurations
(TOP VIEW)
VIN SENSE
54
Marking Information
07=DNN
07= : Product Code
DNN : Date Code
23
LX GND ADJ
TSOT-23-5
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS8472-01 March 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
RT8472
Typical Application Circuit
VIN
5V to 30V
CIN
10µF/50V
RT8472
5 VIN
SENSE 4
RS
optional
3 ADJ
2 GND
LX 1
L
D
Functional Pin Description
Pin No.
1
Pin Name
LX
Pin Function
Switching Node. Open drain output of internal N-MOSFET.
2 GND
3 ADJ
4 SENSE
Ground.
Dimming Control Input :
--- Analog signal input for analog PWM dimming.
--- PWM signal input for digital PWM dimming.
Output Current Sense Terminal. Sense LED string current.
5 VIN
Supply Input Voltage.
Function Block Diagram
VIN
Regulator
Bandgap
UVLO
UVLO
VCC
1.25V
+
-
Ramp Gen.
+ Dimming
ADJ -
SENSE
UVLO
Dimming
MOSFET
LX
GND
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8472-01 March 2013
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