Flyback dc/dc controller eliminates optocoupler

Flyback dc/dc controller eliminates optocoupler

The LT3748 isolated flyback dc/dc controller helps simplify the design of an isolated dc/dc converter. No optoisolator, third winding, or signal transformer is required for feedback since the output voltage is sensed from the primary-side flyback signal. The LT3748 operates over a 5 to 100-V input-voltage range, drives an external n-channel power MOSFET, and is suited for a variety of industrial, medical, telecom, datacom, and automotive applications.

The dc/dc controller operates in boundary mode, which is a variable-frequency current-mode control switching scheme, resulting in ±5% typical regulation over the full line, load, and temperature range. Boundary mode also permits the use of a smaller transformer compared to equivalent continuous conduction-mode designs. The output voltage is set by two external resistors and the transformer turns ratio. Off-the-shelf transformers identified in the datasheet can be used for numerous applications. Additional features include an onboard low dropout regulator for IC power, programmable soft start, undervoltage lockout, adjustable current limit, and output-voltage temperature compensation. The datasheet is available at www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1042,C1113,P112210. (From $3.12 ea/1,000 — available now.)

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