Features

• Wide V_IN Range: 4.5V to 38V
• Line Feedforward Compensation
• Low Minimum On-Time: t_ON(MIN) < 30ns
• Powerful Onboard MOSFET Drivers
• Leading Edge Modulation Voltage Mode Control
• ±0.75%, 0.6V Reference Voltage Accuracy Over Temperature
• V_OUT Range: 0.6V to 0.8V_IN
• Programmable, Cycle-by-Cycle Peak Current Limit
• Sense Resistor or R_DS(ON) Current Sensing
• Programmable Soft-Start
• Synchronizable Fixed Frequency from 250kHz to 1MHz
• Selectable Pulse-Skipping or Forced Continuous Modes of Operation
• Low Shutdown Current: 14μA Typical
• Thermally Enhanced 16-Lead MSOP and 3mm × 3mm QFN Packages

Typical Application

Description

The LTC3775 is a high efficiency synchronous step-down switching DC/DC controller that drives an all N-channel power MOSFET stage from a 4.5V to 38V input supply voltage. A patented line feedforward compensation circuit and a high bandwidth error amplifier provide very fast line and load transient response.

High step-down ratios are made possible by a low 30ns minimum on-time, allowing extremely low duty cycles. MOSFET R_DS(ON) current sensing maximizes efficiency. Alternatively, a sense resistor can be used for higher current limit accuracy. Continuous monitoring of the voltages across the top and bottom MOSFETs allows cycle-by-cycle control of the inductor current, configurable by external resistors.

The soft-start function controls the duty cycle during start-up, providing a smooth output voltage ramp up. The operating frequency is user programmable from 250kHz to 1MHz and can be synchronized to an external clock.