LTC3783 Datasheet, PDF (1/24 Pages) Linear Technology – PWM LED Driver and Boost, Flyback and SEPIC Controller

LTC3783
PWM LED Driver and Boost,
Flyback and SEPIC Controller
FEATURES
DESCRIPTIO
■ _{True Color PWM}^TM _{Delivers Constant Color with}
3000:1 Dimming Ratio
■ _{Fully Integrated Load FET Driver for PWM Dimming}
Control of High Power LEDs
■ _{100:1 Dimming from Analog Inputs}
■ _{Wide FB Voltage Range: 0V to 1.23V}
■ _{Constant Current or Constant Voltage Regulation}
■ _{Low Shutdown Current: IQ = 20µA}
■ _{1% 1.23V Internal Voltage Reference}
■ _{2% RUN Pin Threshold with 100mV Hysteresis}
■ _{Programmable Operating Frequency (20kHz to}
1MHz) with One External Resistor
■ _{Synchronizable to an External Clock Up to 1.3fOSC}
■ _{Internal 7V Low Dropout Voltage Regulator}
■ _{Programmable Output Overvoltage Protection}
■ _{Programmable Soft-Start}
■ _{Can be Used in a No RSENSE}^TM _{Mode for VDS < 36V}
■ _{16-Lead DFN and TSSOP Packages}
U
APPLICATIO S
■ _{High Voltage LED Arrays}
■ _{Telecom Power Supplies}
■ _{42V Automotive Systems}
■ _{24V Industrial Controls}
■ _{IP Phone Power Supplies}
, LTC and LT are registered trademarks of Linear Technology Corporation.
True Color PWM and No R_SENSE are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Patent pending.
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
switching and error amplifier operation, allowing the con-
troller 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 asso-
ciated 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 re-
turned to V_IN, optional constant current/constant voltage
regulation controls either output (or input) current or
output voltage and provides a limit for the other. I_LIM
provides a 10:1 analog dimming ratio.
For low- to medium-power applications, No R_SENSE 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
packages.
TYPICAL APPLICATIO
350mA PWM LED Boost Application
V_IN
6V TO 16V
(< TOTAL V_F OF LEDs)
1M
0.1µF
10µF
10k
LTC3783
105k
6k
RUN
V_IN
PWMIN OV/FB
I_TH PWMOUT
SS
I_LIM
V_REF GATE
FBP SENSE
FBN INTV_CC
FREQ GND
SYNC
M1, M2: SILICONIX Si4470EY
10µF
×2 2.2µH
ZETEX ZLL51000
237k
LED*
STRING
V_OUT
<25V
M1
M2
C_OUT
10µF
4.7µF
0.05Ω 12.4k
*LUMILEDS LHXL-BW02
0.3Ω
GND
3783 TA01a
V_PWMIN
5V/DIV
V_OUT
0.2V/DIV
AC COUPLED
I_L
2.5A/DIV
I_LED
0.5A/DIV
Typical Waveforms
1µs/DIV
3783 TA01b
3783f
1