Forward converter features 95% efficiency

The high reliability (MP-grade) versions of the LT1952/-1, LTC3900 and LT4430 combine to create up to 95% efficient synchronous rectified isolated forward converter. It is specified and production tested over a −55 to +125C operating junction temperature range. The LT1952/-1 is a single switch forward controller with active transformer reset that provides timing signals to the secondary-side LTC3900 synchronous rectifier driver. The LT4430 is a secondary-side optodriver with a precision reference voltage that completes the regulated isolated forward converter circuit. The LTC3900 and LT4430 are specified to a maximum operating junction temperature of +150C.

The forward converter design suits 12, 24 and 48-V nominal input voltages found in telecom, datacom, industrial and military/aerospace applications. The LT1952/-1 includes all the features necessary to implement an active clamp transformer reset. Control outputs include the main power switch control and the active clamp switch control. Additional features include a fixed programmable operating frequency from 100 to 500 kHz, synchronizable up to 750 kHz, selectable maximum duty cycle, adjustable synchronous timing delay, undervoltage lockout, a 100-mV current sense threshold, leading edge blanking and programmable soft start. (Ea/1,000: LT1952/-1MP, $9.35; TC3900MP, $7; LT4430MP, $5.12 – available now.)

By Paul O’Shea

Linear Technology , Milpitas , CA
Sales Office 408-428-2050
www.linear.com