LT3598_1 Datasheet, PDF (1/24 Pages) Linear Technology – 6-String 30mA LED Driver with 1.5% Current Matching

LT3598
6-String 30mA LED Driver
with 1.5% Current Matching
FEATURES
DESCRIPTION
n _{True Color PWM™ Dimming Delivers Up to 3000:1}
Dimming Ratio
n _{Drives Six Strings of LEDs at Up to 30mA}
n _{1.5% Accurate LED Current Matching}
n _{Wide Input Voltage Range: 3.2V to 30V}
n _{Output Voltage Up to 44V}
n _{Regulates Current Even When VIN > VOUT}
n _{Disconnects LEDs in Shutdown}
n _{Programmable Open LED Protection (Regulated)}
n _{OPENLED Alert Pin}
n _{Programmable LED Current Derating}
n _{Adjustable Frequency: 200kHz to 2.5MHz}
n _{Synchronizable to an External Clock}
n _{Parallel Channels for Higher Current per LED String}
n _{Thermally Enhanced 4mm × 4mm QFN and 24-Lead}
TSSOP Packages
APPLICATIONS
n _{Notebook Computer Display}
n _{Medium Size Displays}
n _{Automotive LCD Display}
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.
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. Protected by U.S. Patents, including 7199560, 7321203.
TYPICAL APPLICATION
90% Efficient LED Driver for 60 White LEDs
PV_IN
8V TO 40V
10μH
2.2μF
V_IN
5V
2.2μF
SW
V_IN
100k
OPENLED
SHDN SHDN
PWM
SYNC
PWM
SYNC
LT3598
V_OUT
V_{O_SW}
FB
1.00M
30.9k
51.1k
10k
100k
60.4k
RT
V_REF
CTRL
T_SET I_SET SS
LED1
LED2
LED3
LED4
LED5
LED6
GND VC
47pF
100k
14.7k
10nF
2.61k
15nF
4.7μF
20mA
LED Current Matching
1.5
ALL SIX LED STRINGS
1.0
0.5
0
–0.5
–1.0
–1.5
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3598 TA01b
3598 TA01a
3598fa
1