LT3496_15 Datasheet, PDF (1/20 Pages) Linear Technology – Triple Output LED Driver

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 750mA,}
45V 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 VIN Supply 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}
LT3496
Triple Output LED Driver
Description
The LT^®3496 is a triple output DC/DC converter designed
to operate as a constant-current source and is ideal for
driving LEDs. The LT3496 works in buck, boost or buck-
boost mode. The LT3496 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 LT3496 supports 3000:1 dimming control on each
channel. Each of the three regulators is independently
operated by that channel’s PWM signal. The PWM feature
allows precise adjustment of the color mixing or dimming
ratio of the LED source. 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 LT3496 is
programmed with an external sense resistor.
The CTRL pins are used to adjust the LED currents either
for analog dimming or overtemperature protection.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and True Color PWM are trademarks 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 LED Power Supply
PV_IN
42V
CAP1
200mΩ
LED1
CAP2
CAP3
1µF
200mΩ
200mΩ
s3
LED2
LED3
TG1
TG2
TG3
7 LEDs
0.5A
0.5A
0.5A
3000:1 PWM Dimming at 120Hz
PWM
5V/DIV
I_L
0.5A/DIV
18µH
0.47µF 0.47µF
18µH 18µH
0.47µF
I_LED
0.5A/DIV
V_IN
3V TO 24V
1µF
PWM1, PWM2, PWM3
SHDN
SW1
CAP1, CAP2, CAP3
LED1, LED2, LED3
V_IN
PWM1, PWM2, PWM3
SHDN
SW2
LT3496
GND
SW3 _{TG1, TG2, TG3}
VC1, VC2, VC3
V_REF
CTRL1, CTRL2, CTRL3
f_ADJ
OVP1, OVP2, OVP3
22k
470pF
3496 TA01a
0.5µs/DIV
3496 TA01b
3496ff