A704
APPLICATION INFORMATION
The A704 PWM controller is a monolithic integrated circuit, design for High Brightness LED application,
provides the necessary feature to implement LED driver with a minimal external component needed. Internally
implemented function include, a low start up current and operating current reducing the power dissipation on start-up
resistor, Built-in OVP and UVLO function detected the LED output whether open and short circuit occur, SOT-23
package can save your PCB layout spaces and easy design into place you want, …etc.
Application Circuit:
R6
VDD
EN
R2
R8
A704
CS
Gate
GND
DR
C5
DBR
R7
LED
L1
CX
L2
Q1
CIN1
R4
Bridge
Diode
DF
C8
Fig. 1 - Typical Application circuit
Circuit Topology
A Buck converter is an excellent choice for LED driver in off line application provides a constant LED current.
A peak current controlled buck converter can give reasonable LED current variation over a wide input rang and LED
voltage when the converter is implemented in continuous conduction mode. The A704 is a “Buck” or Step-Down
Converter controller and its typical application circuit was shown as Fig.1. Simplify Fig. 1, its basic schematic can be
seen in Fig.2.
Rsense
Vout
Q1
L
Vin
RLoad
Vd
Cout
DF
Fig 2. Basic Buck converter
Contack Info:Samsun Zhang 13556850583 IC9898@163.com
Copyright © 2008 ADDtek Corp.
6
A704_V0.6 -- AUGUST 2008
ADDTEK [ ADDTEK CORP ]
