Features

• High Efficiency at Full Load
• Better Cross Regulation Than Nonsynchronous Converters (Multiple Outputs)
• Soft-Start Minimizes Inrush Current
• Current Mode Control Provides Excellent Transient Response
• High Maximum Duty Cycle: 89% Typical
• ±2% Programmable Undervoltage Lockout Threshold
• ±1% Internal Voltage Reference
• Micropower Start-Up
• Constant Frequency Operation (Never Audible) 3mm x 4mm 12-Pin DFN Package

Typical Application

Description

The LTC3806 is a current mode synchronous flyback controller that drives N-channel power MOSFETs and requires very few external components. It is intended for medium power applications where multiple outputs are required. Synchronous rectification provides higher efficiency and improved output cross regulation than nonsynchronous converters.

The IC contains all the necessary control circuitry including a 250kHz oscillator, precision undervoltage lockout circuit with hysteresis, gate drivers for primary and synchronous switches, current mode control circuitry and soft-start circuitry.

Programmable soft-start reduces inrush currents. This makes it easier to design compliant Power Over Ethernet supplies.

Low start-up current reduces power dissipation in the start-up resistor and reduces the size of the external startup capacitor.

The LTC3806 is available in a 12-pin, exposed pad DFN package.