|
|
PDF RT8477A Data sheet ( Hoja de datos )
| Número de pieza | RT8477A | |
| Descripción | High Voltage High Current LED Driver | |
| Fabricantes | Richtek | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de RT8477A (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
®
RT8477A
High Voltage High Current LED Driver
General Description
The RT8477A is a current mode PWM controller designed
to drive an external MOSFET for high current LED
applications with wide input voltage (4.5V to 50V) and
output voltage (up to 50V) ranges. With internal 380kHz
operating frequency, the size of the external PWM inductor
and input/output capacitors can be minimized. High
efficiency is achieved by a 100mV current sensing control.
LED Dimming control can be done by analog.
The RT8477A is now available in the SOP-8 (Exposed
Pad) package.
Ordering Information
RT8477A
Package Type
SP : SOP-8 (Exposed Pad-Option 1)
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.
Features
Buck Constant Current Converter
High Voltage : VIN up to 50V, VOUT up to 50V
380kHz Fixed Switching Frequency
Analog or PWM Control Signal for LED Dimming
Internal Soft-Start to Avoid Inrush Current
Under-Voltage Lockout
Thermal Shutdown
Applications
Desk Lights and Room Lighting
Industrial Display Backlight
Pin Configurations
(TOP VIEW)
VCC
ISP
ISN
VC
8
27
GND
36
9
45
CREG
DRV
SENS
CTL
SOP-8 (Exposed Pad)
Marking Information
RT8477AGSP : Product Number
RT8477A
GSPYMDNN
YMDNN : Date Code
Simplified Application Circuit
VIN
Analog Dimming
C1
R5
RT8477A
VCC
C6
ISP
ISN
CTL DRV
CREG SENS
C2
GND
VC
R1
R4
C5
D1
LEDs
C4
L1
R3
C3
M1
R2
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8477A-01 December 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT8477A
Parameter
Symbol
Test Conditions
Min Typ Max Unit
PWM Converter
Switch Frequency
Maximum Duty Cycle
Minimum On-Time
fSW
DMAX
(Note 6)
330 380 430 kHz
-- -- 100 %
-- 200 --
ns
Gate High Voltage
Gate Driver Source
VGATE_H IGATE = 20mA
4.5 5 5.5
1 2.5 --
V
A
Gate Driver Sink
1 3.5 --
A
Soft-Start Time
(Note 7)
-- 2 -- ms
Sense Current Limit Threshold
Over-Temperature Protection
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
ISE NS_LI M
TS D
TSD
100 150 -- mV
-- 150 --
-- 20 --
C
C
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. If connected with a 20kΩ serial resistor, CTL can go up to 40V.
Note 3. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package.
Note 4. Devices are ESD sensitive. Handling precaution is recommended.
Note 5. The device is not guaranteed to function outside its operating conditions.
Note 6. When the natural maximum duty cycle of the switching frequency is reached, the switching cycle will be skipped (not
reset) as the operating condition requires to effectively stretch and achieve higher on cycle than the natural maximum
duty cycle set by the switching frequency.
Note 7. Guaranteed by design, not subjected to production test.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8477A-01 December 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
RT8477A
Layout Considerations
PCB layout is very important when designing power
switching converter circuits. Some recommended layout
guide lines are as follows :
The power components M1, L1, D1 and C4 must be
placed as close to each other as possible to reduce the
ac current loop area. The PCB trace between power
components must be as short and wide as possible
due to large current flow through these traces during
operation.
Place M1, L1 and D1 as close to each other as possible.
The trace should be as short and wide as possible.
The input capacitor C6 must be placed as close to VCC
pin as possible.
VIN power trace to ISP
must be wide and short.
VIN
Keep the ISP and ISN with
The Kelvin sense connection.
ISP
R1
C1
Locate input capacitor as
close VCC as possible.
R5
VCC
ISP
C6 R4
ISN
VC
8
27
GND
36
9
45
CREG
DRV
SENS
CTL
C2
R3
ISN
D1
C4
L1
M1
Power trace must be wide
and short when compared
to the normal trace.
Place these components as
close as possible.
C5 C3 R2
GND
Locate the compensation Components
to VC pin as Close as possible.
Normal trace.
Figure 3. PCB Layout Guide
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS8477A-01 December 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet RT8477A.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| RT8477 | High Voltage High Current LED Driver | Richtek |
| RT8477A | High Voltage High Current LED Driver | Richtek |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |