RT8452
High Voltage High Current LED Driver Controller for Buck
Boost or Buck-Boost Topology
General Description Features
zz z zz High Voltage Capability : V Up to 36V, V Up to
IN OUT
The RT8452 is a current mode PWM controller designed
48V
to drive an external MOSFET for high current LED
zz z zz Buck, Boost or Buck-Boost Operation
applications. With a current sense amplifier threshold of
zz z zz Current Mode PWM with 350kHz Switching
190mV, the LED current is programmable with one
Frenquency
external current sense resistor. With the maximum
zz z zz Easy Dimming Control : Analog or Digital
operating input voltage of 36V and output voltage up to
Converting to Analog with One External Capacitor
48V, the RT8452 is ideal for Buck, Boost or Buck-Boost
zz z zz True PWM Dimming : External FET Driver is Build-
operation.
in
With 350kHz operating frequency, the external inductor
zz z zz Programmable Soft Start to Avoid Inrush Current
and capacitors can be small while maintaining high
zz z zz Programmable Over Voltage Protection
efficiency.
zz z zz V Undervoltage Lockout and Thermal Shutdown
IN
Dimming can be done by either analog or digital. A built-in
zz z zz 16-Lead WQFN and SOP Packages.
clamping comparator and filter allow easy low noise analog
zz z zz RoHS Compliant and Halogen Free
dimming conversion from digital signal with only one
Applications
external capacitor. An unique True PWM dimming control
is made easy with MOSFET under LED string. A very high
z General Industrial High Power LED Lighting
dimming ratio can be achieved by adopting both analog/
z Desk Lights and Room Lighting
digital dimming and True PWM dimming together.
z Building and Street Lighting
z Industrial Display Backlight
The RT8452 is available in WQFN-16L 3x3 and SOP-16
packages.
Pin Configurations
(TOP VIEW)
Ordering Information
GBIAS 16
GND
RT8452 2 15
GATE
VCC
3 14
Package Type PWMOUT OVP
4 13
ISW EN
S : SOP-16
5 12
PWMDIM
NC
QW : WQFN-16L 3x3 (W-Type)
ISP 6 11 SS
7 10
ISN
Lead Plating System DCTL
8 9
VC ACTL
G : Green (Halogen Free and Pb Free)
Note :
SOP-16
Richtek products are :
` RoHS compliant and compatible with the current require-
16 15 14 13
ments of IPC/JEDEC J-STD-020.
GBIAS 1 12 NC
` Suitable for use in SnPb or Pb-free soldering processes. 2 11
GATE SS
GND
3 10
PWMOUT DCTL
17
4 9
ISW ACTL
5 6 7 8
WQFN-16L 3x3
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
DS8452-03 May 2012 www.richtek.com
1
PWMDIM GND
ISP VCC
ISN OVP
VC ENRT8452
Marking Information
RT8452GS RT8452GQW
RT8452GS : Product Number
F4= : Product Code
RT8452
YMDNN : Date Code
YMDNN : Date Code
F4=YM
GSYMDNN
DNN
Typical Application Circuit
L1 R
SENSE
D1
47H
0.09
V
OUT
V
IN
48V (Max.)
C
4.5V to 36V IN C
OUT
10F
1F
RT8452
M1
15 2
GATE
VCC 14 LEDs
R
SW
0.05
13
4
EN
5V
ISW
6
Analog
9
ISP
ACTL
Dimming
7
ISN
10
DCTL
R1
14
OVP V
8 OUT
VC
3
PWMOUT
R
VC 11 R2
SS
10k
5
PWMDIM
1
GBIAS
C
SS
C GND
VC
0.1F
3.3nF
C
B 16, 17 (Exposed Pad)
1F
Figure 1. Analog Dimming in Boost Configuration
R
L1 SENSE
D1
47H 0.09
V
OUT
V
IN
48V (Max.)
4.5V to 36V
C
IN
C
OUT
10F
1F
RT8452
M1
2
15
GATE
VCC
R 14 LEDs
SW
13 0.05
4
EN
5V
ISW
10
6
DCTL
PWM ISP
Dimming control 7
8 ISN
VC
R1
14
V
OVP OUT
R
VC 11
SS
10k 3
PWMOUT
1
GBIAS R2
C
SS
5
C
PWMDIM
VC
0.1F
9
3.3nF
C
ACTL
B
GND
1F
16, 17 (Exposed Pad)
C
A
0.47F
Figure 2. PWM to Analog Dimming in Boost Configuration
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
www.richtek.com DS8452-03 May 2012
2