Isolated Monolithic Flyback Regulator

3rd August 2010

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Datasheet

Linear Technology announced the LT3575, an isolated monolithic flyback switching regulator that significantly simplifies the design of an isolated DC/DC converter. No opto-isolator, third winding or signal transformer are required for feedback since the output voltage is sensed from the primary-side flyback signal. The LT3575 operates over a 3V to 40V input voltage range, has a 2.5A power switch and delivers up to 14 Watts of output power, making it well suited for a wide variety of industrial, medical, telecom, datacom and automotive applications.

The LT3575 operates in boundary mode, which is a variable frequency current-mode control switching scheme, typically resulting in +/-5% 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 LT3575 is available in a small thermally enhanced TSSOP-16 package and is offered in an extended and industrial operating junction temperature range from -40°C to 125°C. Pricing starts at $3.50 each in 1000-piece quantities. For more information, visit www.linear.com/3575.

Summary of Features: LT3575

* VIN Range from 3V to 40V

* Onboard 2.5A, 60V Integrated Power Switch

* No Transformer, Third Winding or Opto-Isolator Required for Feedback

* 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

* Adjustable Current Limit