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PDF LT3596 Data sheet ( Hoja de datos )
| Número de pieza | LT3596 | |
| Descripción | 60V Step-Down LED Driver | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LT3596www.DataSheet4U.com
60V Step-Down LED Driver
Features
n 300mA Buck Regulator, Drives Up to 10 LEDs per
Channel with Fast NPN Current Sources
n Fast Current Sources for <1µs Pulse Widths
(10,000:1 True Color PWM™ Dimming at 100Hz)
n LEDs Disconnected in Shutdown
n Adaptive VOUT for Increased Efficiency
n 6V to 60V Input Voltage Range
n ±1.5% Accurate LED Current Matching
n External Resistors Set LED Current for Each Channel
n Requires No External Compensation
n Programmable Switching Frequency (200kHz to 1MHz)
n Synchronizable to External Clock
n Open, Short LED Detection and Reporting
n Programmable LED Thermal Derating and Reporting
n Programmable Temperature Protection
n 5mm × 8mm Thermally Enhanced QFN Package with
0.6mm High Voltage Pin Spacing
Applications
n LED Billboards and Signboards
n Mono, Multi, Full Color LED Displays
n Large Screen Display LED Backlighting
n Automotive, Industrial and Medical Displays
Description
The LT®3596 is a 60V step-down LED Driver. It achieves
10,000:1 digital PWM dimming at 100Hz with fast NPN
current sources driving up to 10 LEDs in each channel.
100:1 LED dimming can also be done with analog control
of the CTRL1-3 pin.
The step-down switching frequency is programmable
between 200kHz and 1MHz and is synchronizable to an
external clock. The LT3596 also provides maximum LED
brightness while adhering to manufacturers’ specifica-
tions for thermal derating. The derate temperature is
programmed by placing a negative temperature coefficient
(NTC) resistor on the master control pin.
The LT3596 adaptively controls VOUT in order to achieve
optimal efficiency. Other features include: 1.5% LED current
matching between channels, open LED reporting, shorted
LED pin protection and reporting, programmable LED cur-
rent and programmable temperature protection.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation and True Color PWM is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Typical Application
48V 1MHz Step-Down 8W, 100mA LED Driver (Eight White LEDs per Channel)
VIN
48V
VIN
10µF 270k
BIAS
EN/UVLO BOOST
SYNC
91k SW
LT3596
SYNC
DA
RT GND
33.2k
FB
PWM1
PWM2
PWM3
CTRL1
CTRL2
CTRL3
BIAS
FAULT
100k
90.9k
10k
PWM1
PWM2
PWM3
CTRL1
CTRL2
CTRL3
FAULT
VREF
TSET
CTRLM
VOUT
LED1
LED2
LED3
ISET1
ISET2
ISET3
49.9k
100k
5V
4.7µF BIAS
100nF 100µH
100k
3.65k
20k 20k 20k
4.7µF
VOUT
3696 TA01a
10,000:1 PWM Dimming at 100Hz
PWM
2V/DIV
ILED
50mA/DIV
200ns/DIV
3596 TA01b
3596f
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LT3596www.DataSheet4U.com
Typical Performance Characteristics TA = 25°C, unless otherwise noted
VIN Quiescent Current
2.0 VBIAS = 5V
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0 10 20 30 40
VIN VOLTAGE (V)
T = 125°C
T = 25°C
T = –40°C
50 60
3596 G01
UVLO Threshold
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3596 G04
Switching Frequency
1.4
1.2
RT = 33.2k
1.0
0.8
0.6
0.4
0.2 RT = 220k
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3596 G07
BIAS Quiescent Current
2.0
VIN = 24V
1.5
1.0
0.5
0
–0.5
0
T = 125°C
T = 25°C
T = –40°C
5 10 15 20
BIAS VOLTAGE (V)
25
3596 G02
EN/UVLO Pin Current
6
VEN/UVLO = 1.4V
5
4
3
2
1
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3596 G05
SW and DA Current Limit
1100
1000
ISW
900
800
700 IDA
600
500
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3596 G08
VIN, BIAS Shutdown Current
1.4
VIN = 55V
1.2 VBIAS = 25V
1.0
0.8
0.6
0.4
0.2
0
–50 –25
IVBIAS IVIN
0 25 50 75
TEMPERATURE (°C)
100 125
3596 G03
VREF Voltage
2.04
2.03
2.02
2.01
2.00
1.99
1.98
1.97
1.96
–50 –25
VIN = 55V
VIN = 24V
VIN = 6V
0 25 50 75 100 125
TEMPERATURE (°C)
3596 G06
Switch Voltage Drop
1000
900
800
700
600
500
400
300
200
100
0
0
T = 125°C
T = 25°C
T = –40°C
100 200 300 400 500 600 700 800
SWITCH CURRENT (mA)
3596 G09
3596f
5 Page 
LT3596www.DataSheet4U.com
Applications Information
Inductor Selection
Inductor values between 100µH and 470µH are recom-
mended for most applications. It is important to choose
an inductor that can handle the peak current without
saturating. The inductor DCR (copper wire resistance)
must also be low in order to minimize I2R power losses.
Table 1 lists several recommended inductors.
Table 1. Recommended Inductors
PART
MAX
L DCR
(µH) (Ω)
MSS1038
MSS1038
MSS1246T
100 0.3
220 0.76
470 0.935
CDRH10D68
CDRH12D58R
100 0.205
220 0.362
470 0.67
DS1262C2
100 0.17
220 0.35
VLF10040
100 0.22
220 0.47
DR124
DR127
DR74
100 0.26
220 0.56
470 0.861
100 0.383
744771220
220 0.40
CURRENT
RATING
(A)
1.46
0.99
1.0
1.5
1.0
1.01
1.5
1.0
1.3
0.9
1.79
1.15
1.6
0.99
1.2
VENDOR
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
Toko
www.toko.com
TDK
www.tdk.com
Coiltronics
www.cooperet.com
Würth Elektronik
www.we-online.com
Capacitor Selection
Low ESR (equivalent series resistance) capacitors should
be used at the outputs to minimize output ripple voltage.
Use only X5R or X7R dielectrics, as these materials retain
their capacitance over wider voltage and temperature
ranges than other dielectrics. Table 2 lists some suggested
manufacturers. Consult the manufacturers for detailed
information on their entire selection of ceramic surface
mount parts.
Table 2. Recommended Ceramic Capacitor Manufacturers
Taiyo Yuden
www.t-yuden.com
AVX www.avxcorp.com
Murata
www.murata.com
Kemet
www.kemet.com
TDK www.tdk.com
Typically 10µF capacitors are sufficient for the VIN and BIAS
pins. The output capacitor for the buck regulator depends
on the number of LEDs and switching frequency. Refer to
Table 3 for the proper output capacitor selection.
Table 3. Recommended Output Capacitor Values
(Volts/LED = 3.5V)
SWITCHING
FREQUENCY (kHz)
1000
# LEDS
1 to 3
COUT (µF)
6.8
>3 4.7
500 1 to 3 10
>3 6.8
200 1 to 3 22
>3 10
Diode Selection
Schottky diodes, with their low forward voltage drop and
fast switching speed, must be used for all LT3596 ap-
plications. Do not use P-N junction diodes. The diode’s
average current rating must exceed the application’s aver-
age current. The diode’s maximum reverse voltage must
exceed the application’s input voltage. Table 4 lists some
recommended Schottky diodes.
Table 4. Recommended Diodes
PART
MAX
CURRENT
(A)
MAX
REVERSE
VOLTAGE
(V)
DFLS160
1 60
CMMSH1-60
1 60
ESIPB
1 100
MANUFACTURER
Diodes, Inc.
www.diodes.com
Central Semiconductor
www.centralsemi.com
Vishay
www.vishay.com
Undervoltage Lockout (UVLO)
EN/UVLO programs the UVLO threshold by connecting the
pin to a resistor divider from VIN as shown in Figure 2.
Select R1 and R2 according to the following equation:
VIN(UVLO)
=
1.51V
•
1+
R2
R1
3596f
11
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| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet LT3596.PDF ] | |
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