LED Drivers

LT3791IFE#PBF

LT3791IFE#PBF - 60V 4-Switch Sync Buck-Boost LED Driver | ADI

The LT3791IFE#PBF is a synchronous 4-switch buck-boost LED driver controller from Analog Devices, designed to regulate LED current up to 52V with input voltages above, below, or equal to the output voltage. Housed in a 38-pin TSSOP-EP package, this controller operates from a 4.7V to 60V input range and supports constant-frequency, forced-continuous current mode architecture with adjustable frequency from 200kHz to 700kHz. It provides analog and PWM dimming, making it suitable for high-power LED lighting applications. A buck-boost LED driver controller is a power management IC that regulates current through an LED string by stepping up or stepping down the input voltage as needed. Unlike a simple buck or boost converter, the 4-switch topology allows seamless transition between modes, ensuring stable LED current even when the input voltage fluctuates around the output voltage. This makes it ideal for automotive, industrial, and architectural lighting where input voltage variations are common. Key features include a wide 4.7V to 60V input range, output voltage up to 52V, and the ability to drive high-power LEDs with efficiency exceeding 95%. The controller integrates four external MOSFET drivers, supports spread spectrum for low EMI, and includes protection features such as overvoltage, overcurrent, and thermal shutdown. Its constant-frequency operation simplifies EMI filtering and allows synchronization to an external clock. The LT3791 uses a current mode control architecture with a precision reference, enabling accurate LED current regulation. The forced-continuous mode ensures low output ripple and predictable operation across all load conditions. The device also features a low supply current of 4000uA, making it efficient for battery-powered applications. Typical applications include automotive LED headlights, industrial high-bay lighting, architectural lighting, and general-purpose constant-current LED drivers. Its wide input range and buck-boost capability make it versatile for systems with varying supply voltages, such as those powered by batteries or solar panels. When designing with the LT3791, ensure proper PCB layout with short, low-inductance paths for the switching nodes and adequate thermal management for the external MOSFETs. The exposed pad on the TSSOP-EP package should be soldered to a large copper area for heat dissipation.