Features and Benefits
- True Color PWM™ 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™ Mode for VDS < 36V
- 16-Lead DFN and TSSOP Packages
The LTC3783 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 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 regulation 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 synchronized to an external clock using the SYNC pin.
The LTC3783 is available in the 16-lead DFN and TSSOP packages.
- High Voltage LED Arrays
- Telecom Power Supplies
- 42V Automotive Systems
- 24V Industrial Controls
- IP Phone Power Supplies
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 850A is a Boost LED Driver featuring the LTC3783 a boost/SEPIC/flyback LED driver controller. The demo board requires a 3V to 14.4V input and provides 360mA LED current at up to 25V. It incorporates an output overvoltage protection feature to limit output voltage to less than 27V if the LED string is inadvertently disconnected. The LT3783 features 1000:1 PWM dimming for brightness control and analog dimming control.
Tools & Simulations
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Models for the following parts are available in LTspice:
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Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.