Datasheet LTC3783 (Analog Devices)

LTC3783 PWM LED Driver and Boost, Flyback and SEPIC Controller
FEATURES DESCRIPTION
n
True Color PWM
TM
Delivers Constant Color with
The LTC®3783 is a current mode LED driver and boost,
3000:1 Dimming Ratio
flyback and SEPIC controller that drives both an N-channel n
Fully Integrated Load FET Driver for PWM Dimming
power MOSFET and an N-channel load PWM switch. When
Control of High Power LEDs
using an external load switch, the PWMIN input not only n
100:1 Dimming from Analog Inputs
drives PWMOUT, but also enables controller GATE switch- n
Wide FB Voltage Range: 0V to 1.23V
ing and error amplifier operation, allowing the controller n
Constant Current or Constant Voltage Regulation
to store load current information while PWMIN is low. n Low Shutdown Current: IQ = 20µA This feature (patent pending) provides extremely fast, n 1% 1.23V Internal Voltage Reference true PWM load switching with no transient overvoltage n 2% RUN Pin Threshold with 100mV Hysteresis or undervoltage issues; LED dimming ratios of 3000:1 n Programmable Operating Frequency can be achieved digitally, avoiding the color shift normally (20kHz to 1MHz) with One External Resistor associated with LED current dimming. The FBP pin allows n Synchronizable to an External Clock Up to 1.3fOSC analog dimming of load current, further increasing the n Internal 7V Low Dropout Voltage Regulator effective dimming ratio by 100:1 over PWM alone. n Programmable Output Overvoltage Protection In applications where output load current must be returned n Programmable Soft-Start TM to VIN, optional constant current/constant voltage regula- n Can be Used in a No RSENSE Mode for VDS < 36V tion controls either output (or input) current or output n 16-Lead DFN and TSSOP Packages voltage and provides a limit for the other. ILIM provides a
APPLICATIONS
10:1 analog dimming ratio. n For low- to medium-power applications, No RSENSE mode High Voltage LED Arrays n can utilize the power MOSFET’s on-resistance to eliminate Telecom Power Supplies n the current-sense resistor, thereby maximizing efficiency. 42V Automotive Systems n 24V Industrial Controls The IC’s operating frequency can be set with an external n IP Phone Power Supplies resistor over a 20kHz to 1MHz range and can be synchro- nized to an external clock using the SYNC pin. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color PWM and No RSENSE are trademarks of Linear Technology Corporation. The LTC3783 is available in the 16-lead DFN and TSSOP All other trademarks are the property of their respective owners. packages.
TYPICAL APPLICATION 350mA PWM LED Boost Application Typical Waveforms
VIN 6V TO 16V (< TOTAL VF OF LEDs) 10µF 2.2µH VPWMIN 1M ×2 ZETEX ZLLS1000 5V/DIV V LTC3783 OUT <25V VOUT RUN V 0.2V/DIV IN 237k AC COUPLED PWMIN OV/FB LED* STRING ITH PWMOUT IL SS ILIM 105k 2.5A/DIV VREF GATE M1 M2 COUT 0.1µF FBP SENSE 10µF 10µF FBN INTV I CC LED FREQ GND 4.7µF 0.5A/DIV 10k 6k SYNC 0.05Ω 12.4k 0.3Ω GND 1µs/DIV 3783 TA01b 3783 TA01a M1, M2: SILICONIX Si4470EY *LUMILEDS LHXL-BW02 3783fb 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Pin Functions Block Diagram Operation Package Description Related Parts