DC1961A

DC1961A demonstration circuit features the LT®8309, a secondary synchronous driver in an isolated, no optocoupler, flyback converter. It regulates a 12V, 5A output from 36V to 72V input source. Output regulation is handled on the primary side by the LT3748, a boundary conduction mode flyback controller that senses output voltage directly from the primary, resulting in a simple flyback schematic with no opto-coupler. The LT8309 synchronous rectifier driver replicates the behavior of a diode by sensing the synchronous MOSFET drain-to-source voltage to determine its turn on period. By replacing the diode with N-channel MOSFET, applications are no longer restricted by the heat constraints of the rectifier diode.

• Input voltage range from 36 to 72V at TA = 25°C
• Output voltage range from 11.4 to 12.6V at VIN = 36V to 72V, IOUT = 0.15A to 5A, TA = 25°C
• Maximum output current is 5A at TA = 25°C
• Minimum switching frequency is 42kHz at IOUT = 0mA
• 91% efficiency at VIN = 36V, IOUT = 5A