100V Isolated Flyback DC/DC Controller Simplifies Design & Eliminates Optocoupler

The LT3748 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 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 traditionally tough problem of isolated power delivery.

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 LT3748 is available in a small MSOP-16 package with 4 pins removed for additional high voltage pin spacing. This device is available in extended and industrial operating junction temperature range at -40°C to 125°C. Pricing starts at $3.12 each in 1000-piece quantities. For more information, visit www.linear.com/3748.

Summary of Features: LT3748

* VIN Range from 5V to 100V
* No Opto-isolator, Transformer or Third Winding Required for Feedback
* Drives External N-channel Power MOSFET
* Current Mode Control
* Boundary Mode Operation
* VOUT Set with Two External Resistors
* Off-the-Shelf Transformers
* Programmable Soft-Start
* Programmable Undervoltage Lockout
* Output Voltage Temperature Compensation