Features and Benefits
- Three Independent LED Driver Channels
- Wide Input Voltage Range: 2.5V to 40V
- VIN Transient Ride-Through Up to 60V
- Rail-to-Rail LED Current Sense: 0V to 100V
- 3000:1 PWM Dimming
- TG Drivers for PMOS LED Disconnection
- Operates in Boost, Buck Mode, Buck-Boost Mode, SEPIC or Flyback Topology
- Open-LED Protection
- Short-Circuit Protected Boost Capable
- Fault Flags for Independent Channels
- Programmable VIN Undervoltage and Overvoltage Lockout
- Adjustable Switching Frequency: 100kHz to 1MHz
- Synchronizeable to an External Clock
- CTRL Pins Provide Analog Dimming
- Programmable Soft-Start
- Low Profile 52-Lead 7mm x 8mm QFN and 48-Lead Exposed Pad LQFP
The LT3797 is a triple output DC/DC controller designed to drive three strings of LEDs. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. The LT3797 includes an integrated DC/DC converter to produce a regulated 7.5V supply for the N-channel MOSFET gate drivers of the three channels. This high efficiency converter enables the part to operate from a wide input voltage range from 2.5V to 40V.
The LT3797 is designed so that each converter can use the most suitable configuration to drive its LED load, whether step-up, step-down or a combination. Two key features enable this flexibility: first the LT3797 can sense output current at the high side of the LED string; and second, the voltage feedback pin, FBH, is referred to the ISP current sensing input. The CTRL inputs provide output current analog dimming capability. The TG drivers level shift the PWM signals to drive the gates of external LED-disconnect P-channel MOSFETs, allowing high PWM dimming range, and providing LED overcurrent protection and short-circuit protected boost capability.
- Automotive and Industrial Lighting
- RGB Lighting
- Billboards and Large Displays
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 (3)
Demonstration circuit DC2218A is a matrix LED dimmer system featuring the LT3965 8-switch matrix LED dimmer IC. There are 16 500mA LEDs that can be individually turned on, off, or PWM dimmed with two 8-switch LED dimmer LT3965 ICs. The two strings of LEDs are driven with two buck LED driver outputs of the LT3797 triple LED controller IC. The third channel of the LT3797 serves as a 30V pre-boost voltage regulator to provide a proper input voltage to the two buck LED driver channels. DC2218A can be driven from a 9V to 30V input and can survive transients up to 36V.
DC1784B is a triple boost LED driver featuring the LT3797 triple boost LED controller. It accepts an input voltage from 2.5V to 40V (with higher transient) and drives three independent strings of up to 50V LEDs at 1A. DC1784B features independent PWM and analog dimming of each of the three LED strings. Each of the three channels has its own short-circuit protection, open LED protection, and FAULT flag output.
DC1784A is a triple boost LED driver featuring the LT3797 triple boost LED controller. It accepts an input voltage from 2.5V to 40V (with higher transient) and drives three independent strings of up to 50V LEDs at 1A. DC1784A features independent PWM and analog dimming of each of the three LED strings. Each of the three channels has its own short-circuit protection, open LED protection, and FAULT flag output.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LT3797 Companion Parts
Recommended Related Parts
Press Releases (1)
Technical Articles (2)
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Sample & Buy
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