Analog Devices LT3797

Description

The LT®3797 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.

Features

• 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
• 52-Lead QFN Package

Remerks

• Refer Page no-29,L1-L3=10uH,Lpwr=47uH are used.
• Refer Page no-30L1-L3=1uH,Lpwr=47uH are used
• Refer Page no-31L1-L3=33uH,Lpwr=47uH are used
• Refer Page no-32L1-L3=4.7uH,Lpwr=47uH are used
• Refer Page no-33L1-L3=22uH,Lpwr=47uH are used
• Refer Page no-34L1-L3,Lpwr=47uH are used
• Refer Page no-36L1=10uH,L2-L3=22uH,L4=47uH are used
• Refer link-http://cds.linear.com/docs/en/lt-journal/LTJournal-V24N1-05-di-LT3797-KeithSzolusha_.pdf and page no-2

L1-L2=33uH,L3=5.6uH,L4=47uH are used

Typical applications

• Automotive and Industrial Lighting
• RGB Lighting
• Billboards and Large Displays

More information

• Datasheet
• IC product information