LT3598
6-String 30mA LED Driver
with ±1.5% Current Matching
DESCRIPTION
FEATURES
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True Color PWM™ Dimming Delivers Up to 3000:1
Dimming Ratio
Drives Six Strings of LEDs at Up to 30mA
±1.5% Accurate LED Current Matching
Wide Input Voltage Range: 3.2V to 30V
Output Voltage Up to 44V
Regulates Current Even When VIN > VOUT
Disconnects LEDs in Shutdown
Programmable Open LED Protection (Regulated)
OPENLED Alert Pin
Programmable LED Current Derating
Adjustable Frequency: 200kHz to 2.5MHz
Synchronizable to an External Clock
Parallel Channels for Higher Current per LED String
Thermally Enhanced 4mm × 4mm QFN and 24-Lead
TSSOP Packages
APPLICATIONS
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The LT®3598 is a fixed frequency step-up DC/DC converter
designed to drive up to six strings of LEDs at an output
voltage up to 44V. LED dimming can be achieved with
analog dimming on the CTRL pin, and with pulse width
modulation dimming on the PWM pin. The LT3598
accurately regulates LED current even when the input
voltage is higher than the LED output voltage. The switching
frequency is programmable from 200kHz to 2.5MHz
through an external resistor.
Additional features include programmable overvoltage
protection, switching frequency synchronization to an
external clock, LED current derating based on junction
temperature and/or LED temperature, LED string disable
control, OPENLED alert pin and output voltage limiting
when all LED strings are disconnected. The LT3598 is
available in a thermally enhanced 24-lead (4mm × 4mm)
QFN and 24-lead TSSOP packages.
L, LT, LTC, LTM, Linear Technology and the Linear logo 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. Protected by U.S. Patents
including 7199560, 7321203.
Notebook Computer Display
Medium Size Displays
Automotive LCD Display
TYPICAL APPLICATION
LED Current Matching
90% Efficient LED Driver for 60 White LEDs
PVIN
8V TO 40V
10μH
2.2μF
1.5
SW
1.00M
100k
OPENLED
SHDN
PWM
PWM
SYNC
FB
SHDN
SYNC
30.9k
LT3598
RT
51.1k
ALL SIX LED STRINGS
1.0
VO_SW
VIN
MATCHING (%)
VIN
5V
2.2μF
4.7μF
VOUT
0.5
0
–0.5
–1.0
VREF
10k
CTRL
100k
TSET ISET SS
60.4k
47pF
100k
14.7k
–1.5
–50
LED1
LED2
LED3
LED4
LED5
LED6
GND VC
10nF
–25
0
25
50
75
100
125
TEMPERATURE (°C)
20mA
3598 TA01b
2.61k
15nF
3598 TA01a
3598fb
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