Secondary-Side Synchronous Forward Controller with Polyphase Capability

The LTC3706 is a PolyPhase capable secondary-side controller for synchronous forward converters. When used in conjunction with the LTC3705 gate driver and primary-side controller, the part creates a complete isolated power supply that combines the power of PolyPhase operation with the speed of secondary-side control.

The LTC3706 has been designed to simplify the design of highly efficient, secondary-side forward converters. Working in concert with the LTC3705, the LTC3706 forms a robust, self-starting converter that eliminates the need for the separate bias regulator that is commonly used in secondary-side control applications. In addition, a proprietary scheme is used to multiplex gate drive signals and DC bias power across the isolation barrier through a single, tiny pulse transformer.

The LTC3706 provides remote sensing, accurate power good and overvoltage monitoring circuits to support precision, high current applications. A linear regulator controller with thermal protection is also provided to simplify the generation of secondary-side bias voltage.

The LTC3706 is available in a 24-lead SSOP package.

Applications

* Isolated 48V Telecommunication Systems

* Internet Servers and Routers

* Distributed Power Step-Down Converters

* Automotive and Heavy Equipment

* Secondary-Side Control for Fast Transient Response

* Self-Starting Architecture Eliminates Need for Separate Bias Regulator

* Proprietary Gate Drive Encoding Scheme Reduces System Complexity

* PolyPhase® Operation Reduces CIN Requirements

* Current Mode Control Ensures Current Sharing

* PLL Fixed Frequency: 100kHz to 500kHz

* ±1% Output Voltage Accuracy

* True Remote Sense Differential Amplifier

* Power Good Output Voltage Monitor

* High Voltage Linear Regulator Controller

* Wide Supply Range: 5V to 30V

* Available in a Narrow 24-Lead SSOP Package