LINEAR LTC3806 Data Sheet Manual

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LTC3806 Synchronous

Flyback DC/DC Controller

FEATURES DESCRIPTIO High Efficiency at Full Load The LTC®3806 is a current mode synchronous flyback Better Cross Regulation Than Nonsynchronous controller that drives N-channel power MOSFETs and Converters (Multiple Outputs) requires very few external components. It is intended for Soft-Start Minimizes Inrush Current medium power applications where multiple outputs are Current Mode Control Provides Excellent required. Synchronous rectification provides higher effi- Transient Response ciency and improved output cross regulation than High Maximum Duty Cycle: 89% Typical nonsynchronous converters. ±2% Programmable Undervoltage Lockout Threshold

The IC contains all the necessary control circuitry includ-

±1% Internal Voltage Reference

ing a 250k Hz oscillator, precision undervoltage lockout

Micropower Start-Up

circuit with hysteresis, gate drivers for primary and syn-

Constant Frequency Operation (Never Audible)

chronous switches, current mode control circuitry and

3mm × 4mm 12-Pin DFN Package

soft-start circuitry. Programmable soft-start reduces inrush currents. This

APPLICATIO S makes it easier to design compliant Power Over Ethernet

supplies.

48V Telecom Supplies 12V/42V Automotive Low start-up current reduces power dissipation in the 24V Industrial start-up resistor and reduces the size of the external start- Vo IP Phone up capacitor. Power Over Ethernet

The LTC3806 is available in a 12-pin, exposed pad DFN package. , LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

VOUT1

36V TO 72V

C7 3AVOUT2

R1 R2 51k 604k LTC3806

RUN SENSE

R8 ITH SS

FB G2

VIN G1 M1 M2 M3

INTVCC GND

Figure 1. Multiple Output Flyback Converter for Telecom