®
RT8462
High Voltage High Current LED Driver Controller for
Buck, Boost or Buck-Boost Topology
General Description
The RT8462 is a current mode PWM controller designed
to drive an external MOSFET for high current LED
applications. With a current sense amplifier threshold of
190mV, the LED current is programmable with one
external current sense resistor. With the maximum
operating input voltage of 36V and output voltage up to
60V, the RT8462 is ideal for buck, boost or buck-boost
operation.
With the switching frequency programmable over 100kHz
to 1MHz, the external inductor and capacitors can be small
while maintaining high efficiency.
Dimming can be done by either analog or digital. The built-
in clamping comparator and filter allow easy low noise
analog dimming conversion from digital signal with only
one external capacitor.
The RT8462 is available in SOP-14 and WQFN-16L 3x3
packages.
Features
High Voltage Capability : V
IN
Up to 36V, LED Sensing
Threshold Common Mode Voltage Up to 60V
Buck, Boost or Buck-Boost Operation
Programmable Switching Frequency
Easy Dimming Control : Analog or Digital
Converting to Analog with One External Capacitor
Programmable Soft-Start to Avoid Inrush Current
Programmable Over Voltage Protection
V
IN
Under Voltage Lockout and Thermal Shutdown
RoHS Compliant and Halogen Free
Applications
General Industrial High Power LED Lighting
Desk Lights and Room Lighting
Building and Street Lighting
Industrial Display Backlight
Pin Configurations
Ordering Information
RT8462
Package Type
S : SOP-14
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Note :
Richtek products are :
½
(TOP VIEW)
RSET
ISW
ISP
ISN
VC
ACTL
DCTL
14
2
3
4
5
6
7
13
12
11
10
9
8
GATE
GBIAS
GND
VCC
OVP
EN
SS
SOP-14
NC
NC
GATE
GBIAS
16 15 14 13
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.
RSET
ISW
ISP
ISN
1
2
3
4
12
½
GND
17
5
6
7
8
11
10
9
GND
VCC
OVP
EN
WQFN-16L 3x3
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8462-07 November 2015
VC
ACTL
DCTL
SS
www.richtek.com
1
RT8462
Marking Information
RT8462GS
RT8462GS : Product Number
RT8462ZQW
82 : Product Code
YMDNN : Date Code
RT8462
GSYMDNN
82 YM
DNN
YMDNN : Date Code
Typical Application Circuit
L1
22µH
V
IN
4.5V to 36V
C
IN
10µF
11
5V
Analog
Dimming
VCC
D1
C
OUT
1µF
R
SW
0.05
R
SENSE
0.47
V
OUT
60V (Max.)
LEDs
RT8462
GATE 14
ISW 2
3
ISP
4
ISN
10
OVP
1
RSET
GND 12
9 EN
6 ACTL
7 DCTL
5 VC
8
SS
13 GBIAS
M1
R1
R2
R
RSET
30k
V
OUT
R
VC
10k
C
VC
3.3nF
C
SS
0.1µF
C
B
1µF
Figure 1. Analog Dimming in Boost Configuration
D1
V
IN2
60V (Max.)
V
IN1
4.5V to 36V C
IN1
10µF
RT8462
11
5V
Analog
Dimming
VCC
ISP 3
ISN 4
GATE
14
M1
R
SW
0.05
9 EN
6 ACTL
7 DCTL
5 VC
8
SS
13 GBIAS
C
B
1µF
C
OUT
1µF
C
IN2
R
SENSE
0.47
LEDs
L1
22µH
R
VC
10k
C
VC
3.3nF
C
SS
0.1µF
ISW 2
RSET 1
OVP 10
GND
12
R
RSET
Figure 2. Analog Dimming in Buck Configuration
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8462-07 November 2015
RT8462
V
IN2
60V (max)
V
IN1
4.5V to 36V
C
IN1
10µF
11
5V
Analog
Dimming
C
IN2
L1
22µH
D1
V
OUT
C
OUT
1µF
R
SENSE
0.47
R1
R
RSET
R2
RT8462
VCC
GATE
14
9 EN
6 ACTL
7 DCTL
5
VC
8
ISW 2
4
ISN
3
ISP
10
OVP
1
RSET
GND 12
M1
R
SW
0.05
LEDs
V
OUT
R
VC
10k
C
VC
3.3nF
C
SS
0.1µF
SS
13 GBIAS
C
B
1µF
Figure 3. Analog Dimming in Buck-Boost Configuration
Functional Pin Description
Pin No.
SOP-14
1
2
3
4
5
6
7
8
9
10
11
12
13
14
--
WQFN-16L 3x3
1
2
3
4
5
6
7
8
9
10
11
Pin Name
RSET
ISW
ISP
ISN
VC
ACTL
DCTL
SS
EN
OVP
VCC
Pin Function
Switch Frequency Set Pin. Connect a resistor from RSET to GND.
R
RSET
= 30k will set f
SW
= 370kHz.
External MOSFET Switch Current Sense. Connect the current sense
resistor between external N-MOSFET switch and the ground.
LED Current Sense Amplifier Positive Input with Common Mode Up to
60V.
LED Current Sense Amplifier Negative Input. Voltage threshold
between ISP and ISN is 190mV with common mode voltage up to 60V.
PWM Control Loop Compensation.
Analog Dimming Control. The effective programming voltage range of
the pin is between 0.2V and 1.2V.
By adding a 0.47F filtering capacitor on ACTL pin, the PWM dimming
signal on DCTL pin can be averaged and converted into analog
dimming signal on the ACTL pin.
Soft-Start. A capacitor of at least 10nF is required for proper soft-start.
Chip Enable (Active High). When this pin voltage is low, the chip is in
shutdown mode.
Over Voltage Protection. The PWM converter turns off when the
voltage of the pin goes to higher than 1.18V.
Power Supply Pin of the Chip. For good bypass, a low ESR capacitor
is required.
Ground. The Exposed Pad must be Soldered to a Large PCB and
Connected to GND for Maximum Power Dissipation.
Internal Gate Driver Bias. A good bypass capacitor is required.
External MOSFET Switch Gate Driver Output.
No Internal Connection.
is a registered trademark of Richtek Technology Corporation.
12,
GND
17 (Exposed Pad)
13
GBIAS
14
GATE
15, 16
NC
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
DS8462-07 November 2015
www.richtek.com
3
RT8462
Function Block Diagram
VOC
8.5V
EN
RSET
VCC
1.4V
+
-
-
+
-
Shutdown
OSC
GBIAS
S
Q
GATE
4.5V
OVP
1.18V
+
R
+
-
R
R
-
+
110mV
ISW
-
+
VC
6µA
SS
DCTL
1.2V
+
-
1.2V
+
-
-
GM
+
ISN
ISP
GND
ACTL
V
ISP
– V
ISN
(mV)
V
190
0
0.2
1.2
V
ACTL
(V)
Figure 4
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8462-07 November 2015
RT8462
Absolute Maximum Ratings
(Note 1)
−0.3
to 38V
−0.3
to 10V
−0.3
to 1V
−0.3
to 66V
−0.3
to 8V (Note 2)
−0.3
to 20V
Supply Input Voltage, VCC ----------------------------------------------------------------------------------------
GBIAS, GATE --------------------------------------------------------------------------------------------------------
ISW ---------------------------------------------------------------------------------------------------------------------
ISP, ISN ----------------------------------------------------------------------------------------------------------------
DCTL, ACTL, OVP --------------------------------------------------------------------------------------------------
EN -----------------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOP-14 ---------------------------------------------------------------------------------------------------------------- 1.0W
WQFN-16L 3x3 ------------------------------------------------------------------------------------------------------ 1.471W
Package Thermal Resistance (Note 3)
SOP-14,
θ
JA
----------------------------------------------------------------------------------------------------------- 100°C/W
WQFN-16L 3x3,
θ
JA
------------------------------------------------------------------------------------------------- 68°C/W
WQFN-16L 3x3,
θ
JC
------------------------------------------------------------------------------------------------ 7.5°C/W
Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
Storage Temperature Range --------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 4)
HBM (Human Body Model) ---------------------------------------------------------------------------------------- 2kV
MM (Machine Model) ----------------------------------------------------------------------------------------------- 200V
(Note 5)
Recommended Operating Conditions
Supply Input Voltage Range, VCC ------------------------------------------------------------------------------- 4.5V to 36V
Junction Temperature Range --------------------------------------------------------------------------------------
−40°C
to 125°C
Electrical Characteristics
Parameter
Overall
Supply Current
Shutdown Current
EN Threshold
Voltage
EN Input Current
Current Sense Amplifier
Input Threshold (V
ISP
V
ISN
)
ISP Input Current
ISN Input Current
VC Output Current
VC Threshold for PWM
Switch Off
I
ISP
I
ISN
I
VC
Logic-Low
I
VCC
I
SHDN
V
IL
Logic-High V
IH
(V
CC
= 24V, No Load on any Output, T
A
= 25°C, unless otherwise specified)
Symbol
Test Conditions
V
VC
0.4V (Switching off)
V
EN
0.7V
Min
--
--
2
--
Typ
6
12
--
--
--
Max
7.2
--
--
0.5
1.2
Unit
mA
A
V
A
V
EN
3V
V
ACTL
1.25V,
12V
common mode
60V
1.25V
V
ACTL
1.2V, (Note 7)
12V
common mode
60V
4.5V
V
ISP
60V
4.5V
V
ISN
60V
0.5V
V
C
2.4V
--
182
--
--
--
--
--
190
188
140
60
20
0.7
198
mV
--
--
--
--
--
A
A
A
V
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8462-07 November 2015
www.richtek.com
5
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