PWM LED Driver and Boost,
Flyback and SEPIC Controller
n True Color PWMTM Delivers Constant Color with
3000:1 Dimming Ratio
n Fully Integrated Load FET Driver for PWM Dimming
Control of High Power LEDs
n 100:1 Dimming from Analog Inputs
n Wide FB Voltage Range: 0V to 1.23V
n Constant Current or Constant Voltage Regulation
n Low Shutdown Current: IQ = 20µA
n 1% 1.23V Internal Voltage Reference
n 2% RUN Pin Threshold with 100mV Hysteresis
n Programmable Operating Frequency
(20kHz to 1MHz) with One External Resistor
n Synchronizable to an External Clock Up to 1.3fOSC
n Internal 7V Low Dropout Voltage Regulator
n Programmable Output Overvoltage Protection
n Programmable Soft-Start
n Can be Used in a No RSENSETM Mode for VDS < 36V
n 16-Lead DFN and TSSOP Packages
n High Voltage LED Arrays
n Telecom Power Supplies
n 42V Automotive Systems
n 24V Industrial Controls
n IP Phone Power Supplies
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
True Color PWM and No RSENSE are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LTC®3783 is a current mode LED driver and boost,
flyback and SEPIC controller that drives both an N-channel
power MOSFET and an N-channel load PWM switch. When
using an external load switch, the PWMIN input not only
drives PWMOUT, but also enables controller GATE switch-
ing and error amplifier operation, allowing the controller
to store load current information while PWMIN is low.
This feature (patent pending) provides extremely fast,
true PWM load switching with no transient overvoltage
or undervoltage issues; LED dimming ratios of 3000:1
can be achieved digitally, avoiding the color shift normally
associated with LED current dimming. The FBP pin allows
analog dimming of load current, further increasing the
effective dimming ratio by 100:1 over PWM alone.
In applications where output load current must be returned
to VIN, optional constant current/constant voltage regula-
tion controls either output (or input) current or output
voltage and provides a limit for the other. ILIM provides a
10:1 analog dimming ratio.
For low- to medium-power applications, No RSENSE mode
can utilize the power MOSFET’s on-resistance to eliminate
the current-sense resistor, thereby maximizing efficiency.
The IC’s operating frequency can be set with an external
resistor over a 20kHz to 1MHz range and can be synchro-
nized to an external clock using the SYNC pin.
The LTC3783 is available in the 16-lead DFN and TSSOP
350mA PWM LED Boost Application
6V TO 16V
(< TOTAL VF OF LEDs)
M1, M2: SILICONIX Si4470EY *LUMILEDS LHXL-BW02