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PDF LT3597 Data sheet ( Hoja de datos )
| Número de pieza | LT3597 | |
| Descripción | 60V Triple Step-Down LED Driver | |
| Fabricantes | Linear | |
| Logotipo |  |
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Features
n Three 100mA Buck Regulators, Each Drives Up to
10 LEDs 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 ±2% LED Current Matching
n External Resistor Sets LED Current for Each Channel
n Internal Compensation and Soft-Start
n Programmable Switching Frequency (200kHz to 1MHz)
n Synchronizable to External Clock
n Open LED Detection and Reporting
n Shorted LED Pin Protection and Reporting
n Programmable LED Thermal Derating
n Programmable Temperature Protection
n 5mm × 8mm Thermally Enhanced QFN Package
with a 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
LT3597
60V Triple Step-Down
Description
LED Driver
The LT®3597 is a 60V triple step-down LED driver capable
of achieving 10,000:1 digital PWM dimming at 100Hz with
fast NPN current sources driving up to 10 LEDs in each
channel. LED dimming can also be achieved via analog
control of the CTRL1-3 pin.
The step-down switching frequency is programmed be-
tween 200kHz and 1MHz. The frequency is also synchroniz-
able to an external clock. The LT3597 provides maximum
LED brightness while adhering to manufacturers’ speci-
fications for thermal derating. The derate temperature is
programmed by placing a negative temperature coefficient
(NTC) resistor on the master control pin.
The LT3597 adaptively controls VOUT in order to achieve
optimal efficiency. Other features include: 2% LED cur-
rent matching between channels, open LED reporting,
shorted LED protection, programmable LED current, and
programmable temperature protection.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color
PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of
their respective owners.
Typical Application
Triple Step-Down RGB Single Pixel LED Driver, 100mA Current
VIN
48V
10µF 270k
91k
VOUT1
100µH
97k 3.3µF
R 9.1k
VIN
EN/UVLO
BOOST1
0.1µF
SW1
DA1
FB1
LT3597
BOOST2
SW2
DA2
FB2
VOUT2
LED2
BOOST3
VOUT1
LED1
VCC BIAS
5V 10µF 100k
SW3
DA3
FB3
3
3
FAULT
PWM1-3
CTRL1-3
VOUT3
LED3
SYNC
RT
VREF
33.2k
ISET1
ISET2
ISET3
TSET
GND CTRLM
(1MHz)
20k 20k 20k
3597 TA01a
0.1µF 100µH
VOUT2
3.3µF 97k
9.1k
0.1µF 100µH
VOUT3
3.3µF 97k
9.1k
VREF
10k 82.5k
49.9k
100k
10,000:1 PWM Dimming at 100Hz
G
PWM
2V/DIV
ILED
50mA/DIV
B
200ns/DIV
3597 TA01b
3597fa
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1 page  
LT3597
Typical Performance Characteristics TA = 25°C, unless otherwise noted.
VIN Quiescent Current
3.0 VBIAS = 5V
2.5 125°C
2.0 –40°C
1.5 25°C
1.0
0.5
0
0 10 20 30 40 50 60
VIN VOLTAGE (V)
3597 G01
VBIAS Quiescent Current
3.0 VIN = 24V
125°C
2.5 25°C
2.0 –40°C
1.5
1.0
0.5
0
–0.5
0
5 10 15 20
VBIAS VOLTAGE (V)
25
3597 G02
Shutdown Current
2.00 VIN = 55V
1.75 VBIAS = 25V
1.50
1.25
1.00
0.75
0.50 IVIN
0.25 IBIAS
0
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3597 G03
UVLO Threshold Voltage (Falling)
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3597 G04
EN/UVLO Pin Bias Current
6
5 EN/UVLO = 1.4V
4
3
2
1
0
–50 –25
EN/UVLO = 1.6V
0 25 50 75 100 125
TEMPERATURE (°C)
3597 G05
VREF Voltage
2.04 VREF LOAD = 0µA
2.03
2.02
2.01 VIN = 24V
VIN = 55V
2.00
VIN = 6V
1.99
1.98
1.97
1.96
–50 –25
0 25 50 75 100 125
TEMPERATURE (°C)
3597 G06
Switching Frequency
1.2
1.0 RT = 33.2k
0.8
0.6
0.4
0.2 RT = 220k
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3597 G07
Current Limit
600
SWITCH
500
400
300 DA
200
100
0
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3597 G08
Switch Voltage Drop
600 VBIAS = 5V
500
125°C
400 25°C
–40°C
300
200
100
0
0 50 100 150 200 250
SWITCH CURRENT (mA)
3597 G09
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LT3597
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
CURRENT
L (µH) DCR (Ω) RATING (A)
LPS6225
MSS1038
MSS1038
MSS1038
100 0.61
100 0.3
220 0.76
470 1.24
0.52
1.46
0.99
0.70
CDRH105R
100 0.253
CDRW105R
220 0.50
CDRH105R
470 1.29
CDR6D28MN 100
0.9
1.35
0.94
0.60
0.75
DS1262C2
DS1262C2
DS1262C2
100 0.17
220 0.35
470 1.243
1.5
1.0
0.7
SLF10145T
SLF10145T
100 0.26
220 0.47
1.0
0.7
DR73
DR73
100 0.527
220 1.05
0.79
0.53
VENDOR
Coilcraft
www.coilcraft.com
Sumida
www.sumida.com
Toko
www.toko.com
TDK
www.tdk.com
Coiltronics
www.cooperet.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 regulators 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 (VLED = 3.5V)
SWITCHING FREQUENCY (kHz)
1000
# LEDS
1-3
COUT (µF)
3.3
>3 2.2
500 1-3 4.7
>3 3.3
200 1-3 15
>3 6.8
Diode Selection
Schottky diodes, with their low forward voltage drop and
fast switching speed, must be used for all LT3597 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 MAX REVERSE
(A) VOLTAGE (V) MANUFACTURER
DFLS160
B160
1
1
60 Diodes, Inc.
60 www.diodes.com
CMMSH1-60
1
60 Central
www.centralsemi.com
ESIPB
1 100 Vishay
www.vishay.com
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11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LT3597.PDF ] | |
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