Driver Controller. RT8494 Datasheet

RT8494 Controller. Datasheet pdf. Equivalent

RT8494 Datasheet
Recommendation RT8494 Datasheet
Part RT8494
Description High Voltage High Current LED Driver Controller
Feature RT8494; ® RT8494 High Voltage High Current LED Driver Controller for Buck, Boost or Buck-Boost Topology Ge.
Manufacture Richtek
Datasheet
Download RT8494 Datasheet




Richtek RT8494
®
RT8494
High Voltage High Current LED Driver Controller for
Buck, Boost or Buck-Boost Topology
General Description
The RT8494 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
90V, the RT8494 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 RT8494 is available in SOP-14 package.
Features
High Voltage Capability : VIN up to 36V, LED Sensing
Threshold Common Mode Voltage up to 90V
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
VIN Under-Voltage Lockout and Thermal Shutdown
AEC-Q100 Compliance
Applications
General Industrial High Power LED Lighting
Desk Lights and Room Lighting
Building and Street Lighting
Industrial Display Backlight
Ordering Information
RT8494
Package Type
S : SOP-14
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Pin Configurations
(TOP VIEW)
RSET
ISW
ISP
ISN
VC
ACTL
DCTL
2
3
4
5
6
7
14
13
12
11
10
9
8
SOP-14
GATE
GBIAS
GND
VCC
OVP
EN
SS
Marking Information
RT8494
GSYMDNN
RT8494GS : Product Number
YMDNN : Date Code
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS8494-00 January 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT8494
RT8494
Typical Application Circuit
VIN
4.5V to 36V
5V
Analog
Dimming
1R0VkC
3C.V3CnF
L1
22µH
1C0INµF
RT8494
11 VCC
GATE 14
9 EN
ISW 2
C0.S1SµF
6 ACTL
7 DCTL
5 VC
8 SS
13 GBIAS
C1µBF
ISP 3
ISN 4
OVP 10
RSET 1
GND 12
D1
RSENSE
0.47
COUT
1µF
M1
RSW
0.05
R1
RRSET
30k
R2
VOUT
VOUT
90V (Max.)
LEDs
Figure 1. Analog Dimming in Boost Configuration
VIN1
4.5V to 36V 1C0IµNF1
5V
Analog
Dimming
1R0VkC
3C.V3CnF
CSS
0.1µF
VIN2
90V (Max.)
CIN2
RT8494
11 VCC
9 EN
ISP 3
ISN 4
6 ACTL
7 DCTL
5 VC
8 SS
13 GBIAS
C1µBF
GATE 14
ISW 2
RSET 1
OVP 10
GND
12
D1
COUT
1µF
RSENSE
0.47
LEDs
L1
22µH
M1
R0.S0W5
RRSET
Figure 2. Analog Dimming in Buck Configuration
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8494-00 January 2015



Richtek RT8494
RT8494
VIN1
4.5V to 36V
5V
Analog
Dimming
1R0VkC
3C.V3CnF
VIN2
90V (max)
CIN2
L1
22µH
1C0INµ1F
C0.S1SµF
RT8494
11 VCC
GATE 14
9 EN
ISW 2
6 ACTL
7 DCTL
5 VC
8 SS
13 GBIAS
ISN 4
ISP 3
OVP 10
RSET 1
GND 12
M1
RRSET
CB
1µF
D1
0R.S0W5
COUT
1µF
RSENSE
0.47
R1
R2
VOUT
Figure 3. Analog Dimming in Buck-Boost Configuration
VOUT
LEDs
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
Pin Name
RSET
ISW
ISP
ISN
VC
ACTL
DCTL
Pin Function
Switch Frequency Setting. Connect a resistor from RSET to GND. RRSET = 30kwill
set fSW = 350kHz.
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 90V.
LED Current Sense Amplifier Negative Input. Voltage threshold between ISP and
ISN is 190mV with common mode voltage up to 90V.
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.
8 SS
Soft-Start Time Setting. A capacitor of at least 10nF is required for proper soft-start.
9 EN
10 OVP
Enable Control Input (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.
11 VCC
Power Supply of the Chip. For good bypass, a low ESR capacitor is required.
12 GND
Ground. The Exposed Pad must be Soldered to a Large PCB and Connected to
GND for Maximum Power Dissipation.
13 GBIAS Internal Gate Driver Bias. A good bypass capacitor is required.
14 GATE
External MOSFET Switch Gate Driver Output.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS8494-00 January 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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