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RT8471
1.2A/1A, Hysteretic, High Brightness LED Driver with Internal Switch
General Description
The RT8471 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 7V to 36V and employs hysteretic control with a high side current sense resistor to set the constant output current.
The RT8471 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 RT8471 is available in a small TSOT-23-5 package or a more thermal efficient SOP-8 (Exposed Pad) and MSOP8 (Exposed Pad) packages.
Ordering Information
RT8471 Package Type J5 : TSOT-23-5 SP : SOP-8 (Exposed Pad-Option 1) FP : MSOP-8 (Exposed Pad)
Lead Plating System G : Green (Halogen Free and Pb Free)
(for MSOP-8 (Exposed Pad) and TSOT-23-5 ) Z : ECO (Ecological Element with Halogen Free and Pb free) (for SOP-8 (Exposed Pad) Only)
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
7V to 36V Input Voltage Range Hysteretic Control with High Side Current Sensing Internal N-MOSFET with 350mΩ Low RDS(ON) 1A Output Current (For TSOT-23-5 Only) 1.2A Output Current (For SOP-8 (Exposed Pad) and
MSOP-8 (Exposed Pad) Only) Up to 97% Efficiency Typical ±5% LED Current Accuracy Analog or PWM Control Signal for LED Dimming 300Hz On-Board Ramp Generator Input Under Voltage Lockout Thermal Shutdown Protection RoHS Compliant and Halogen Free
Applications
Automotive LED Lighting High Power LED Lighting Indicator and Emergency Lighting Architectural Lighting Low Voltage Industrial Lighting Signage and Decorative LED Lighting
Marking Information
RT8471GJ5
01=DNN
01= : Product Code DNN : Date Code
RT8471ZSP
RT8471 ZSPYMDNN
RT8471ZSP : Product Number YMDNN : Date Code
RT8471GFP
0D=YM DNN
0D= : Product Code YMDNN : Date Code
Copyright ©2013 Richtek Technology Corporation. All rights reserved. DS8471-02 December 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com 1
RT8471
Pin Configurations
VIN SENSE
54 23
LX GND ADJ TSOT-23-5
(TOP VIEW)
VIN SENSE
GND ADJ
8 27
GND
36 9
45
GND LX NC NC
SOP-8 (Exposed Pad)
SENSE GND
GND ADJ
8
2 GND 7
3 96 45
VIN NC LX LX
MSOP-8 (Exposed Pad)
Typical Application Circuit
VIN 7V to 36V
CIN
RT8471 VIN SENSE
RS optional
ADJ GND
LX
L
D
Functional Pin Description
TSO T-23-5 1
2
3
4 5
Pin No.
SOP-8 (Exposed Pad)
7
MSOP-8 (Exposed Pad)
5, 6
Pin Name LX
3, 8, 9 (Exposed Pad)
2, 3, 9 (Exposed Pad)
GND
4 4 ADJ
2 1 SENSE 1 8 VIN
Pin Function
Switch O utput Terminal. Dr ai n of inter nal N-MOSFET.
Ground. The exposed pad must be.