LT3748 Isolated Flyback Controller

By Analog Devices Inc 69

LT3748 Isolated Flyback Controller

Linear Technology's LT3748 is a switching regulator controller specifically designed for the isolated flyback topology and capable of high power. It drives a low side external N-channel power MOSFET from an internally regulated 7 V supply. No third winding or opto-isolator is required for regulation, as the part senses the isolated output voltage directly from the primary-side flyback waveform.

The LT3748 utilizes boundary mode to provide a small magnetic solution without compromising load regulation. Operating frequency is set by load current and transformer magnetizing inductance. The gate drive of the LT3748, combined with a suitable external MOSFET, allow it to deliver load power up to several tens of watts from input voltages as high as 100 V.

  • 5 V to 100 V input voltage range
  • 1.9 A average gate drive source and sink current
  • Boundary mode operation
  • No transformer third winding or opto-isolator required for regulation
  • Primary-side winding feedback load regulation
  • VOUT set with two external resistors
  • INTVCC pin for control of gate driver voltage
  • Programmable soft-start
  • Programmable undervoltage lockout
  • Isolated telecom converters
  • High power automotive supplies
  • Isolated industrial power supplies

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