LT3965EFE-1#PBF

The LT3965EFE-1#PBF is a highly efficient, current-mode, synchronous, step-up (boost) converter with integrated power FETs specifically designed to drive high-brightness LEDs at up to 1A with over 90 percent efficiency in a small solution size. It offers a wide input voltage range from 2.7V to 24V and can provide positive or negative output voltage from 6V to 28V with a maximum output power of 40W. Its circuit incorporates a configurable feedback reference voltage for dimming control, an internal soft-start, output short circuit shutdown and over-temperature protection. The LT3965EFE-1#PBF LED driver features a tiny 3mm x 3mm DFN-6 package and low component count, allowing design engineers to minimize component count, space and total cost of the LED system.

The LT3965EFE-1#PBF device is ideal for automotive lighting, decorative and accent lighting applications. It works over a wide temperature range, from -40°C to 125°C, and makes managing the LEDs brightness easy by setting the feedback voltage at different levels, depending on desired light output. This control allows for gradual brightness changes, accurate dimming of multiple LEDs and the ability for one device to properly control both a single and multiple LEDs outputs.

In order to operate properly and safely, the LT3965EFE-1#PBF employs a configurable synchronous boost converter with a current mode architecture. The first stage of the synchronous boost converter is a low side N-channel MOSFET and a diode as the power switch and rectifying element. The current on this switch is regulated according to the current-mode architecture. If a voltage is applied to VFB, then the output current is linearly regulated. When the load current drops, the device reduces PWM pulses to maintain the output voltage, allowing the device to respond to changes in load and temperature. The second stage of the synchronous boost converter is an H-bridge consisting of four N-channel MOSFETs, which acts as a series power switch.

The LT3965EFE-1#PBF features an adjustable dimming control which is set through an external resistor. The voltage on VFB is compared to the reference voltage at the inverted input of the error amplifier and the resistor divider, which is set by the reference voltage at INTVCC pin. A positive amplifier output will enable to output switches and source current from VIN through the DRAIN pin. When the VFB voltage is above the reference voltage, the integrated PWM controller initiates a PFM burst mode, preventing the device from overheating due to an output short circuit or over-current situation. The LT3965EFE-1#PBF also provides a soft-start, which helps to limit the inrush current drawn from the input capacitor during start-up.

The need for external components with the LT3965EFE-1#PBF LED driver is fairly minimal, allowing it to be used in a wide variety of applications. It requires only an input capacitor, an output inductor and output capacitor to operate the device. The selection of inductor and output capacitors can vary depending on the application. In addition, the LT3965EFE-1#PBF also requires an external sensing resistor to set the current, a feedback voltage divider and a soft-start capacitor. For current limiting and dimming control, an NTC resistor and a bias resistor may also be used.

The LT3965EFE-1#PBF from Linear Technology is a high-efficiency, current-mode, synchronous, step-up (boost) converter specifically designed for driving high-brightness LEDs. Its tiny 3mm x 3mm DFN-6 package size and low component count make it an ideal solution for automotive lighting, decorative and accent lighting applications. With a wide input voltage range from 2.7V to 24V and output voltage from 6V to 28V, it offers accurate dimming control, soft-start and short-circuit protection in a highly efficient and cost-effective solution.