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100V No-Opto Flyback Regulator Delivers Up To 5 Watts In TSOT-23 Package


Linear Technology Corporation announces the LT8303, a monolithic flyback regulator in a TSOT-23 package that significantly simplifies the design of isolated DC/DC converters. By sampling the isolated output voltage directly from the primary-side flyback waveform, the part requires no optoisolator, LT1431 or third winding for regulation. The LT8303 operates over a 5.5V to 100V input voltage range, has a 0.45A/150V integrated DMOS power switch and delivers up to 5 watts of output power, making it well suited for a wide range of telecom, datacom, automotive, industrial, medical and military applications.

The output voltage is set with only one external resistor and the transformer turns ratio. Several off-the-shelf transformers, identified in the data sheet, can be used for numerous applications. The LT8303 operates in boundary mode, which is a variable frequency current-mode control switching scheme, typically resulting in ±5% output voltage regulation over the full line, load, and temperature range. Boundary mode enables the use of a smaller transformer compared to equivalent continuous conduction mode designs. The high level of integration and the use of low ripple Burst Mode operation result in a simple to use, low component count and high-efficiency application solution for isolated power delivery.

Additional features include output short-circuit protection, 70µA no load operating quiescent current, internal loop compensation, accurate enable and under voltage lockout with hysteresis.

Extended and industrial versions operate over a junction temperature range of –40°C to 125°C. Pricing starts at $3.15 each in 1000-piece quantities.

Summary of Features: LT8303

  • VIN Range from 5.5V to 100V
  • Up to 5W of Output Power
  • Onboard 0.45A, 150V Integrated DMOS Power Switch
  • Off-the-Shelf Power Transformers
  • No Opto-Isolator, LT1431 or Third Winding Required for Voltage Feedback
  • 70µA Quiescent Current
  • Boundary Mode Operation
  • VOUT Set with One External Resistor
  • Internal Loop Compensation
  • Accurate Input Enable & Undervoltage Lockout with Hysteresis
  • Small 5-Lead TSOT Package

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