Isolated Flyback Switching Regulator simplifies converter design.

Press Release Summary:

Operating from 3-40 V, monolithic LT3575 has 2.5 A, 60 V power switch and delivers up to 14 W output. It consolidates isolated DC/DC converter design by negating need for opto-isolator, third winding, and signal transformer for feedback; output voltage is sensed from primary-side flyback signal. Boundary mode operation typically results in ±5% regulation over full line, load, and temperature range. Other features include LDO regulator, programmable soft-start and undervoltage lockout.

Original Press Release:

Isolated Monolithic Flyback Regulator Simplifies Design & Eliminates Optocoupler

MILPITAS, CA - Linear Technology Corporation announces 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

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

    About Linear Technology
    Linear Technology Corporation, a manufacturer of high performance linear integrated circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major public companies in 2000. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, µModule® products, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.
    LT, LTC, LTM, µModule and are registered trademarks of Linear Technology Corp. All other trademarks are the property of their respective owners.

    North America and General Information
    John Hamburger
    Tel: (408) 432-1900 ext. 2419

    Doug Dickinson
    Tel: (408) 432 1900 ext. 2233

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