The device simplifies the design of an isolated DC/DC converter since there is no requirement for an opto-isolator, third winding or signal transformer for feedback, as the output voltage is sensed from the primary-side flyback signal. The LT3748 operates over a 5 V to 100 V input voltage range and drives an external N-channel power MOSFET, making it well suited for a wide variety of automotive, industrial, telecom and datacom applications.

The LT3748 operates in a boundary mode, 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 easily set by two external resistors and the transformer turns ratio. Several off-the-shelf transformers identified in the data sheet can be used for numerous applications. The high level of integration and the use of boundary mode operation results in a simple, clean application solution to the traditional challenge of isolated power delivery.

Additional features include an onboard low drop regulator for IC power, programmable soft start, undervoltage lockout, adjustable current limit and output voltage temperature compensation.

Availability and Pricing

The LT3748H is available in a small MSOP-16 package with 4 pins removed for additional high voltage pin spacing. The 1,000 piece price starts at $3.71 each.

More information about the LT3748H high input voltage isolated flyback DC/DC controller at www.linear.com/3748.

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