|
|
PDF AND8470 Data sheet ( Hoja de datos )
| Número de pieza | AND8470 | |
| Descripción | Single Stage Power Factor Corrected Constant Current Offline LED Driver | |
| Fabricantes | ON Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de AND8470 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
|
No Preview Available !
AND8470/D
A 25 to 55 V, 0.7 to 1.5 A,
Single Stage Power Factor
Corrected Constant Current
Offline LED Driver with
Flexible Dimming Options
http://onsemi.com
Prepared by: Frank Cathell
ON Semiconductor
Introduction
This application note describes a 40 to 90 W, off−line,
single stage power factor correction (PFC), isolated constant
current LED driver. There are a wide variety of medium
power lighting applications that would benefit from
replacing the traditional light source with an LED source
including outdoor area lights, parking garages lights, wall
washers, wall packs and architectural lighting. All these
applications have high operating hours, challenging
environmental conditions, and can benefit from advanced
dimming control to further save energy. Moreover many of
these applications have accessibility issues so long lifetime
LED based solutions could significantly reduce
maintenance costs.
This specific driver design is tailored to support LEDs
such as the Cree XLamp™ XP−G and XM, OSRAM
Golden DRAGON LED® Plus, and Philip−Lumileds
Luxeon® Rebel that have maximum drive currents of
700 mA to 1500 mA. These example LEDs exhibit good
efficacy’s at higher drive currents, thus allowing fewer
LEDs to be used to achieve the same light output. For
example, a cool white Cree XP−G driven at 1 A can generate
280 − 320 lm typical at a junction temperature of 80°C with
an efficacy in the range of 100 lm/W. If 14 of these were used
in a wall pack, the source lumen output would be
approximately 4200 lm excluding optical losses and the
typical load power would be ~43 W.
This application note focuses on various options for
dimming including PWM, analog and bi−level dimming.
Intelligent dimming takes full advantage of the instant
turn−on characteristics of LEDs and combines it with
lighting controls to save significant energy without
compromising lighting quality or user safety and comfort. In
many cases, these techniques have not been used in the past
as some traditional large area light sources are difficult to
easily dim and may have long re−strike times. Additionally,
LED lifetime improves when dimmed because the average
operating junction temperature is reduced. PWM and analog
dimming are traditional techniques for dimming. Bi−level or
multi−level dimming involves establishing discrete drive
current steps to support a range of light level. This method
combined with sensors / controls (motion, occupancy, timer
based, or remotely networked control) allows additional
APPLICATION NOTE
energy savings without compromising safety and
convenience. This is especially useful in outdoor and
underground lighting were bi−level control can reduce the
light level based on time−of−day and occupancy to save
power late at night when there is no activity, but still allows
the light to return to standard light levels in the presence of
activity. In fact the California Lighting Technology recently
published a study where bi−level LED lighting saved 87%
over conventional 70 W HID outdoor pathway bollards.
The power supply is designed around
ON Semiconductor’s NCL30001 single stage, continuous
conduction mode (CCM) PFC controller and the NCS1002
secondary side constant voltage, constant current (CVCC)
controller. Details of the operation of the NCL30001 are also
discussed in AND8427 where the power stage design is
discussed for a static (non−dimming) application.
Additional circuitry has been added to the CVCC control
loop to support three types of dimming control: analog
dimming with a 1 to 10 V programming signal; bi−level
dimming with a simple logic level input signal; and PWM
dimming using an onboard 800 Hz oscillator with variable
pulse width. These three dimming functions are
incorporated on an optional plug−in DIM card that can be
wired into the NCL30001LEDGEVB evaluation board. The
demo board already has a standard input which accepts a
user provided logic level PWM input signal which can be
varied from 350 Hz to several kilohertz.
The basic specification of the demo board are listed below.
The maximum output voltage can be adjusted via selection
of a single resistor; and it is compliant enough to handle an
output with a nominal 2:1 forward voltage range. This 2:1
range is dependent on the string series forward voltage and
the drive current. The default output current is set at 1 A, but
a maximum DC output current of 1.5 A is available by
modifying a single resistor value. This power level of this
design is targeted at applications operation below 60 Vdc
maximum and below 100 VA to be under the maximum
power requirements of IEC (EN) 60950−1 (UL1310
Class 2) power supplies. The demo board is illustrative of a
typical operational schematic. If a higher voltage is required
to drive a longer string of LEDs, then several secondary
components would need to be changed and the transformer
design would need to be modified.
© Semiconductor Components Industries, LLC, 2010
July, 2010 − Rev. 0
1
Publication Order Number:
AND8470/D
Free Datasheet http://www.datasheetlist.com/
1 page  
AND8470/D
Xfmr
8
11
1000uF, 63V x 3
R24 C19
100, 1/2W 1nF
D8
C20 C21 C22
C23
0.1
100V
R26
0.10
C24
0.1
100V
PWM Output
Switch
MMSZ5245B NTD12N10T4G
MURH860CTG
R28
Q4 MJD243GR27
Vcc = 14V
4.7K, 0.5W
2W
C34 0.1
U2
feedback
optocoupler
2.2k R29
1 43k
C25
0.1
2 D11
MMSD4148
Z4
MMSZ5245B
7
C30
8
−
U3B
+
6
5
1uF NCS1002
Is
R31
2.7k
C31
Is 1nF
Vs
C26 0.1
D12
MMSD4148
R30 43k
1
−
U3A
4+
2
Vref
3
R32
68K
2.5V
R34
R33 82k
6.2k
To Primary
Ground Plane
C27 2.2nF
internal
to U3
C35 C32
0.1 10nF
R35
3.9k
GND
Current Sense
Sample & Hold
Z5
Q7
R37
C33
0.1uF
5.1k
MMBTA06LT1G
Q6 R39
R36
2.7K
R38
Q5 100
2N7002KT1G
R40
10k
10k
R44
10k
6
Vcc R41 5
10 Jumper if DIM
Card not used
R42
10
R43
10
3
2
1
P1
+
LED Anode
J2
LED Cathode
−
J3
PWM In
Gnd 1 kHz
1 kHz PWM
Out
Vcc In
Vref In
Analog
Dim out
Dimming
Control
Options
Card
Common
R32 output current setting:
43K for 1.5 A out
68K for 1.0 A out
50V/1.0A LED Driver CVCC Secondary Sensing with
PWM Dimming Input & Option Card (Rev 3A)
Figure 2. Secondary Sensing and PWM Control Schematic
Figure 3 is the schematic of the optional plug−in control
card which supports dimming via three methods. These
include analog dimming using a 1 to 10 V signal adjustable
by a 15 turn potentiometer. An external, remote 100k
potentiometer can be used by removing this potentiometer
and wiring in the remote one with the PCB solder pads
provided. The second dimming option is a bi−level mode
which is typically used with an occupancy sensor, motion
sensor, or microcontroller input to reduce the current level
for reduced light output when there is no activity in an area.
When activity is detected then the driver is switched to the
standard higher drive current level. A simple logic level
signal input is used for this control. The third method is
PWM dimming where the output is switched on and off at
an appropriate frequency by gating output MOSFET Q7.
This dimming technique is preferred when the color point of
the LED needs to be maintained regardless of brightness
level. This is accomplished by modulating the desired peak
LED current between on and off based on duty ratio thus
changing the average LED current. An on−board 800 Hz
oscillator circuit with potentiometer adjustable pulse width
is incorporated on the DIM card to demonstrate this
dimming method.
http://onsemi.com
5
Free Datasheet http://www.datasheetlist.com/
5 Page 
AND8470/D
WAVEFORMS PLOTS
Figure 6. Output Current Turn−on Profile; 1 A output;
500 mA/Division
Figure 8. Output Current Ripple: 1.5 A Output
(500 mA/division)
Figure 7. Output Current Ripple: 1 A Output
(200 mA/division)
Figure 9. PWM Dimming Current Waveform Plots: D
= 50%; I peak = 1 A
http://onsemi.com
11
Free Datasheet http://www.datasheetlist.com/
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet AND8470.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AND8470 | Single Stage Power Factor Corrected Constant Current Offline LED Driver | ON Semiconductor |
| AND8470D | Single Stage Power Factor Corrected Constant Current Offline LED Driver | ON Semiconductor |
| 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 |