LT3492_15 Datasheet, PDF (1/22 Pages) Linear Technology – Triple Output LED Driver with 3000:1 PWM Dimming

FEATURES
n _{True Color PWM™ Dimming Delivers Up to 3000:1}
Dimming Ratio
n _{Built-In Gate Driver for PMOS LED Disconnect}
n _{Three Independent Driver Channels with 600mA,}
60V Internal Switches
n _{Operates in Buck, Boost, Buck-Boost Modes}
n _{CTRL Pin Accurately Sets LED Current Sense}
Threshold Over a Range of 10mV to 100mV
n _{Adjustable Frequency: 330kHz to 2.1MHz}
n _{Open LED Protection}
n _{Wide Input Voltage Range:}
Operation from 3V to 30V
Transient Protection to 40V
n _{Surface Mount Components}
n _{28-Lead (4mm × 5mm) QFN and TSSOP Packages}
APPLICATIONS
n _{RGB Lighting}
n _{Billboards and Large Displays}
n _{Automotive and Avionic Lighting}
n _{Constant-Current Sources}
LT3492
Triple Output LED Driver
with 3000:1 PWM Dimming
DESCRIPTION
The LT^®3492 is a triple output DC/DC converter designed
to operate as a constant-current source and is ideal for
driving LEDs. The LT3492 works in buck, boost or buck-
boost mode. The LT3492 uses a fixed frequency, current
mode architecture resulting in stable operation over a
wide range of supply and output voltages. A frequency
adjust pin allows the user to program switching frequency
between 330kHz and 2.1MHz to optimize efficiency and
external component size.
The external PWM input provides 3000:1 LED dimming
on each channel. Each of the three channels has a built-in
gate driver to drive an external LED-disconnect P-channel
MOSFET, allowing high dimming range. The output current
range of each channel of the LT3492 is programmed with
an external sense resistor.
The CTRL pin is used to adjust the LED current either for
analog dimming or overtemperature protection.
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, and others pending.
TYPICAL APPLICATION
High Dimming Ratio Triple Output Buck-Mode LED Power Supply
PV_IN
58V
ISP1
330mΩ
ISN1
ISP2
330mΩ
ISN2
TG1
TG2
ISP3
1μF
330mΩ
s3
ISN3
TG3
10 LEDs
0.3A
0.3A
0.47μF 0.47μF
0.3A
0.47μF
33μH
33μH
33μH
V_IN
3V TO 24V
1μF
SW1
ISP1-3
ISN1-3
V_IN
PWM1-3
SHDN
SW2
LT3492
GND
SW3
TG1-3
V_C1-3
V_REF
CTRL1-3
FADJ
OVP1-3
150k
10k
49.9k
1.3MHz
680pF
3492 TA01a
3000:1 PWM Dimming at 100Hz
PWM
5V/DIV
I_LED
0.2A/DIV
I_L
0.5A/DIV
1μs/DIV
3492 TA01b
3492fa
1