|
|
PDF LM3414HV Data sheet ( Hoja de datos )
| Número de pieza | LM3414HV | |
| Descripción | 1A 60W Common Anode Capable Constant Current Buck LED Driver Requires | |
| Fabricantes | National Semiconductor Corporation | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LM3414HV (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
LM3414HV 1A 65V LED
Driver Evaluation Board
National Semiconductor
Application Note 2076
SH Wong
August 10, 2010
Introduction
The LM3414HV is a 65V floating buck LED driver that de-
signed to drive up to 18 pieces of serial High Brightness LEDs
(HBLEDs) with up to 1000mA LED forward current. With the
incorporation of the proprietary Pulse-Level-Modulation
(PLM) technology, the LM3414HV requires no external cur-
rent sensing resistor to facilitate LED current regulation. The
LM3414HV features a dimming control input (DIM pin) that
allows PWM dimming control. The LM3414HV is available in
LLP-8 (3mm x 3mm outline) and ePSOP8 to fulfil the require-
ments of small solution size and high thermal performance
respectively. In order to demonstrate the performance of the
LM3414 family, the LM3414HV is selected for the evaluation
boards because of the wide input voltage range (4.5V to 65V)
providing the best flexibility to fit the requirements of different
applications. Two versions of evaluation board with identical
schematic are available with the LM3414HV in either LLP-8
or PSOP-8 package. The board with LLP-8 package demon-
strates the high power density of the device. The board with
PSOP-8 package demonstrates the functionality of the
LM3414HV with enhanced thermal performance. The
schematic, bill of materials and PCB layout for the evaluation
boards are provided in this document. The evaluation boards
can be adapted to different application requirements by
changing the values of a few components only. This evalua-
tion board is also suitable for the LM3414 with maximum
acceptable input voltage reduced to 42VDC.
Standard Settings of the LM3414HV
Evaluation Board
Vin range: 4.5V to 65V
No. of LEDs: 1 - 18
LED current: 1A
Switching frequency: 500 kHz
FIGURE 1. Standard Schematic for the LM3414HV Evaluation Board
30128701
© 2010 National Semiconductor Corporation 301287
www.national.com
1 page  
age drop across RPTC increases as the resistance of RPTC
increases. As the emitter voltage of Q1 reaches 1.255V, ther-
mal foldback control is activated and the LED current reduces
according to IEXT.
FIGURE 4. Thermal Foldback Control with PTC thermistor
30128721
Design Example
The LM3414HV evaluation board is used to drive a LED string
at 700mA and thermal foldback control is needed to take
place when the temperature of the LED strings exceeds 80°
C as presented in Figure 5.
RPTC(25C) = 330Ω
RPTC(80C) = 1.2kΩ
RPTC(100C) = 10kΩ
In Figure 5, the LED current with the LED temperature below
80°C (ILED(normal)) is 700mA. As the temperature of the LED
goes up to 80°C, thermal foldback begins and reduces the
LED driving current with respect to the increase of resistance
of RPTC. As the temperature of the LEDs reaches 100°C, the
LED current reduces to zero. Provided that the resistance of
the thermistor RPTC under 80C and 100°C are 1.2kΩ and
10kΩ respectively, the values of R1 and R2 can be calculated
following the steps listed below.
At 80°C:
30128722
FIGURE 5. Reduction of LED current with thermal
foldback control
Assume the resistance of the PTC thermistor under 25°C, 80°
C and 100°C are:
5
(8)
www.national.com
5 Page 
Notes
11 www.national.com
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LM3414HV.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LM3414HV | LM3414/HV 1-A 60-W Common Anode-Capable Constant Current Buck LED Driver Requires No External Current Sensing Resistor (Rev. F) |  Texas Instruments |
| LM3414HV | 1A 60W Common Anode Capable Constant Current Buck LED Driver Requires | National Semiconductor Corporation |
| 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 |