|
|
PDF RT4503 Data sheet ( Hoja de datos )
| Número de pieza | RT4503 | |
| Descripción | Asynchronous Boost Converter | |
| Fabricantes | Richtek Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de RT4503 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
|
No Preview Available !
®
RT4503/A
Asynchronous Boost Converter for 10 WLEDs
General Description
The RT4503/A is a highly integrated LED driver IC capable
of driving 10 WLEDs in series. It is composed of a current
mode Boost converter integrated with a 36V/1.2A power
switch.
The RT4503/A supports a wide input voltage range from
2.5V to 5.5V and runs at a fixed frequency of 550kHz.
The LED current is set via an external resistor and the
feedback voltage is regulated to 200mV.
For brightness dimming, the RT4503A supports 32 steps
pulse dimming which determines the feedback reference
voltage, and RT4503 support PWM dimming which
determines the feedback reference voltage.
Applications
Cellular Phones
Digital Cameras
Probable Instruments
Features
2.5V to 5.5V Input Voltage Range
36V Open LED Protection for 10 WLEDs
Pulse Dimming Brightness Control
200mV Reference Voltage with ±2% Accuracy
550kHz Switching Frequency
Built-In Soft-Start
Over-Temperature Protection
Internal Compensation
Current Limit
Ordering Information
RT4503/A
Package Type
QW : WDFN-6L 2x2 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
RT4503 : PWM Dimming
RT4503A : Pulse Dimming
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.
Simplified Application Circuit
VIN
L
LX
VIN
RT4503/A
EN
GND
COMP*
FB
* : COMP pin for RT4503 only.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS4503/A-03 June 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
1 page  
RT4503/A
Parameter
Symbol
Test Conditions
Min Typ Max Unit
Voltage and Current Control
Feedback Regulation Voltage
Feedback Pin Bias Current
VFB
IFB
196 200 204 mV
-- -- 0.1 A
Oscillator Frequency
fSW
495 550 605 kHz
Maximum Duty Cycle
DMAX
-- 93 -- %
Power Switch
N-MOSFET On-Resistance
RDS(ON) VIN = 3.6V
-- 0.4 0.7
OC and OLP
Peak N-MOSFET Current Limit ILIM
1 1.2 1.4 A
Open LED Protection Threshold OVP
35 36.5 38
V
Thermal Shutdown
Thermal Shutdown Threshold TSD
-- 160 --
°C
Thermal Shutdown Hysteresis TSD
-- 15 -- °C
N ote 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. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. First EN pulse for pulse dimming see Timing Diagram.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS4503/A-03 June 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
5 Page 
RT4503/A
Pulse Dimming
The EN pin features a simple digital interface to allow digital
brightness control. Using the digital interface to control
the LED brightness does not require a PWM signal.
The digital brightness control is implemented by adjusting
the feedback voltage in digital steps with a typical
maximum voltage of VFB = 200mV. For this purpose, a 5-
bit DAC is used to display 32 steps equaling to a 6.25mV
change in feedback voltage per step.
THI 40µs
CTRL 0
0.5µs < THi
0.5µs < TLO < 1000µs
200mV
1 23456789
TSHDN > 2ms
0
(23/32) x 200mV
FB 0
Inductor Selection
The recommended value of inductor for 10 LEDs or high
brightness LED applications is 22μH. Smaller size and
better efficiency are the major concerns for portable
devices. The inductor should have low core loss at 550kHz
and low DCR for better efficiency. The inductor saturation
current rating should be considered to cover the inductor
peak current.
Capacitor Selection
For low ripple voltage, ceramic capacitors with low ESR
are recommended. X5R and X7R types are suitable
because of their wide voltage range and good operating
temperature characteristics. For the application of the
RT4503/A to drive 10 LEDs in series, a 2.2μF for input
capacitor, a 1μF for output capacitor.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
PD(MAX) = (TJ(MAX) − TA) / θJA
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
WDFN-6L 2x2 package, the thermal resistance, θJA, is
47.5°C/W on a standard JEDEC 51-7 four-layer thermal
test board. The maximum power dissipation at TA = 25°C
can be calculated by the following formula :
PD(MAX) = (125°C − 25°C) / (47.5°C/W) = 2.1W for
WDFN-6L 2x2 package
The maximum power dissipation depends on the operating
ambient temperature for fixed TJ(MAX) and thermal
resistance, θJA. The derating curve in Figure 1 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS4503/A-03 June 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet RT4503.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| RT4501 | High Efficiency Backlight LED Driver | Richtek Technology |
| RT4501A | High Efficiency Backlight LED Driver | Richtek Technology |
| RT4503 | Asynchronous Boost Converter | Richtek Technology |
| RT4503A | Asynchronous Boost Converter | Richtek Technology |
| 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 |