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PDF LT3590 Data sheet ( Hoja de datos )
| Número de pieza | LT3590 | |
| Descripción | 48V Buck Mode LED Driver | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT3590 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
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FEATURES
■ 4.5V to 55V Input Voltage Range
■ Up to 50mA LED Current
■ 80mA, 55V Switch
■ Internal Schottky Diode
■ 15μA Supply Current in Shutdown
■ 500μA Supply Current Operating, Not Switching
■ Switching Frequency: 850kHz
■ 200mV Feedback Voltage with ±5% Accuracy
■ CTRL Input Performs Dimming and Shutdown
■ 91% Efficiency (10 LEDs, 50mA)
■ Requires Only 1μF Output Capacitor
■ 8-Lead SC70 Package
■ 6-Lead 2mm × 2mm DFN Package
APPLICATIONS
■ LED Fixed Signage
■ Traffic Signs
■ Neon Sign Replacement
LT3590
48V Buck Mode
LED Driver in SC70
and 2mm x 2mm DFN
DESCRIPTION
The LT®3590 is a fixed frequency buck mode converter
specifically designed to drive up to 10 LEDs in series from
a 48V DC source. Series connection of the LEDs provides
identical LED currents of up to 50mA, resulting in uniform
brightness and eliminating the need for ballast resistors.
A fixed frequency, current mode architecture results in
stable operation over a wide range of input voltage and
output voltage.
The high switching frequency of 850kHz permits the use
of tiny, low profile inductors and capacitors. A single pin
performs both shutdown and accurate LED dimming
control. The power switch, Schottky diode and control
circuitry are all contained inside a space saving SC70
package or 2mm × 2mm DFN package to allow a small
converter footprint and lower parts cost.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
VIN
48V
CONTROL
Buck Mode Driver for Ten White LEDs
1μF
50mA
4Ω
1μF
0.1μF
VIN LED
CTRL
LT3590
VREG
SW
GND
470μH
3590 TA01a
Conversion Efficiency
100
90
80
70
60
50
40
0 10 20 30 40 50
LED CURRENT (mA)
3590 TA01b
3590f
1
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TYPICAL PERFORMANCE CHARACTERISTICS
LT3590
Sense Voltage (VIN – VLED)
vs VCTRL
0.25
VIN = 48V
ILED = 50mA
0.20 TA = 25°C
0.15
0.10
0.05
0
0 0.5 1 1.5 2
VCTRL (V)
3590 G09
Sense Voltage (VIN – VLED)
vs VIN
206
ILED = 50mA
10 WHITE LEDs
204 TA = 25°C
202
200
198
196
194
0 10 20 30 40 50 60
VIN (V)
3590 G12
Internal Regulator
Line Regulation
3.40
TA = 25°C
3.35
VCTRL = 0V
ILOAD = 0V
3.30
VCTRL = 3.3V
ILOAD = 1mA
3.25
Switching Current Limit
vs Duty Cycle
150
TA = 25°C
140
130
120
110
100
90
80
0 20 40 60 80 100
DUTY CYCLE (%)
3590 G10
Sense Voltage (VIN – VLED)
vs Temperature
206
204
202
200
198
196
194
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3590 G13
Internal Regulator
Load Regulation
3.40
TA = 25°C
3.35
VCTRL = 0V
ILED = 0V
3.30
VCTRL = 3.3V
ILED = 50mA
3.25
Switching Current Limit
vs Temperature
150
140
130
120
110
100
90
80
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3590 G11
Switching Frequency over
Temperature
1000
VIN = 48V
950
900
850
800
750
700
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3590 G14
Internal Regulator
VREG vs Temperature
3.40
VCTRL = 3.3V
ILOAD = 1mA
3.35
3.30
3.25
3.20
0
10 20 30 40 50 60
VIN (V)
3590 G15
3.20
0
0.2 0.4 0.6 0.8
1
ILOAD (mA)
3590 G16
3.20
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3590 G17
3590f
5
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LT3590
APPLICATIONS INFORMATION
The dimming range can be further extended by changing
the amplitude of the PWM signal. The height of the PWM
signal sets the commanded sense voltage across the sense
resistor through the CTRL pin. In this manner both analog
dimming and direct PWM dimming extend the dimming
range for a given application. The color of the LEDs no
longer remains constant because the forward current of
the LED changes with the height of the CTRL signal. For
the ten LED application described above, the LEDs can be
dimmed first, modulating the duty cycle of the PWM signal.
Once the minimum duty cycle is reached, the height of the
PWM signal can be decreased below 1.5V down to 150mV.
The use of both techniques together allows the average
LED current for the ten LED application to be varied from
50mA down to less than 50μA.
Internal Voltage Regulator
The LT3590 has a 3.3V onboard voltage regulator capable
of sourcing up to 1mA of current for use by an external
device. This feature may be used to power-up a controller
from the LT3590. The 3.3V is available even during shut-
down. It is required to place a 0.1μF capacitor from VREG
to ground. The regulator current is limited to 1.5mA.
Board Layout Considerations
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To prevent electromagnetic interference (EMI) problems,
proper layout of high frequency switching paths is essen-
tial. Minimize the length and area of all traces connected
to the switching node pin (SW). Keep the sense voltage
pins (VIN and LED) away from the switching node. Place
the output capacitor, C2, next to the VIN pin. Always use
a ground plane under the switching regulator to minimize
interplane coupling. Recommended component placement
is shown in Figure 8.
VREG
CTRL
VIN
VREG
C3
CTRL
5
6
7
8
VIN C1
R1 C2
OUT
LED
GND
4
3
2
1
L1
SW
(a) SC70 Package
GND
CTRL
GND
C3
CTRL
GND
VREG
16
2 75
3 4 VIN
C1
SW
R1
C2
LED
L1 OUT
GND
VREG
VIN
(b) 2mm × 2mm DFN Package
3590 F08
Figure 8. Recommended Component Placement
3590f
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT3590.PDF ] | |
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