RT8458D Buck Controller Datasheet

RT8458D Datasheet, PDF, Equivalent


Part Number

RT8458D

Description

Constant Current PWM Buck Controller

Manufacture

Richtek

Total Page 13 Pages
Datasheet
Download RT8458D Datasheet


RT8458D
®
RT8458D
High Voltage, High Efficiency, Constant Current PWM Buck
Controller for LED Lighting
General Description
The RT8458D is a PWM controller with an internal high
side gate driver. Because of the Buck topology, the input
voltage for the Buck system is only limited by the voltage
rating of the external MOSFET. It is used for step down
converters by well controlling the external MOSFET and
regulating a constant output current. The output duty cycle
of the RT8458D can be up to 100% for wider input voltage
application.
The RT8458D also features a 160kHz fixed frequency
oscillator, an internal 220mV precision reference, and a
PWM comparator with latching logic. The accurate output
LED current is achieved by an averaging current feedback
loop and the LED current dimming can be easily controlled
via the ACTL pin. The RT8458D also has multiple features
to protect the controller from fault conditions, including
Under Voltage Lockout (UVLO), Over Current Protection
(OCP) and Over Voltage Protection (OVP). Additionally,
to ensure the system reliability, the RT8458D is built with
the thermal protection function.
The RT8458D is housed in a TSOT-23-6 package. Thus,
the components in the whole LED driver system can be
made very compact.
Features
Low Cost and Efficient Buck Converter Solution
Input Voltage Depends On External MOSFET
Programmable Constant LED Current
Dimmable LED Current by ACTL
100% Maximum Duty Cycle
160kHz Fixed Switching Frequency
Output LED String Open Protection
Output LED String Short Protection
Output LED String Over Current Protection
Built-in Thermal Protection
TSOT-23-6 Package
RoHS Compliant and Halogen Free
Applications
E27, PAR30, Offline LED Lights
Marking Information
13=DNN
13= : Product Code
DNN : Date Code
Simplified Application Circuit
RVCC
CVCC
CVC2
RVC
CVC1
RT8458D
VCC ACTL
VC GATE
GND SENSE
CIN
D2
VIN
Analog
Dimming
Q1
RS
D1
L1
COUT
LED+
LED-
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8458D-07 May 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT8458D
RT8458D
Ordering Information
RT8458D
Package Type
J6 : TSOT-23-6
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Pin Configurations
(TOP VIEW)
SENSE VC ACTL
654
23
VCC GND GATE
TSOT-23-6
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 VCC
2 GND
Supply Voltage Input of the chip. For good bypass, a ceramic capacitor near the
VCC pin is required.
Ground of the Chip.
3 GATE
Gate Driver Output for External MOSFET Switch.
4 ACTL
Analog Dimming Control Input. Dimming signal can still be applied to ACTL pin.
ACTL dimming signal high is internally clamped around 1.3V. The sourcing and
sinking current should be limited to no more than 10A.
5 VC
PWM Loop Compensation Node.
6
SENSE
LED Current Sense Input. The typical sensing threshold is 220mV between the
SENSE and GND pin.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8458D-07 May 2014


Features ® RT8458D High Voltage, High Efficienc y, Constant Current PWM Buck Controller for LED Lighting General Description The RT8458D is a PWM controller with an internal high side gate driver. Becaus e of the Buck topology, the input volta ge for the Buck system is only limited by the voltage rating of the external M OSFET. It is used for step down convert ers by well controlling the external MO SFET and regulating a constant output c urrent. The output duty cycle of the RT 8458D can be up to 100% for wider input voltage application. The RT8458D also features a 160kHz fixed frequency oscil lator, an internal −220mV precision r eference, and a PWM comparator with lat ching logic. The accurate output LED cu rrent is achieved by an averaging curre nt feedback loop and the LED current di mming can be easily controlled via the ACTL pin. The RT8458D also has multiple features to protect the controller fro m fault conditions, including Under Vol tage Lockout (UVLO), Over Current Protection (OCP) and Over Voltag.
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