Synchronous Rectifier Driver for Forward Converters

The LTC3900 is a secondary-side synchronous rectifier driver designed to be used in isolated forward converter power supplies. The chip drives N-channel rectifier MOSFETs and accepts pulse sychronization from the primary-side controller via a pulse transformer.

The LTC3900 incorporates a full range of protection for the external MOSFETs. A programmable timeout function is included that disables both drivers when the synchronization signal is missing or incorrect. Additionally, the chip senses the output inductor current through the drainsource resistance of the catch MOSFET, shutting off the MOSFET if the inductor current reverses. The LTC3900 also shuts off the drivers if the supply voltage is too low.

Applications

* 48V Input Isolated DC/DC Converters

* Isolated Telecom Power Supplies

* High Voltage Distributed Power

Step-Down Converters

* Industrial Control System Power Supplies

* Automotive and Heavy Equipment

* N-Channel Synchronous Rectifier MOSFET Driver

* Programmable Timeout Protection

* Reverse Inductor Current Protection

* Pulse Transformer Synchronization

* Wide VCC Supply Range: 4.5V to 11V

* 15ns Rise/Fall Times at VCC = 5V, CL = 4700pF

* Undervoltage Lockout

* Small SO-8 Package