6W, isolated regulator eliminates opto-coupler, uses off-the-shelf magnetics

March 10, 2014 // By Graham Prophet
LT8301 is a monolithic flyback regulator that 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 opto-isolator or third winding for regulation.

The LT8301 operates over a 2.7V to 42V input voltage range, has a 1.2A/65V power switch and delivers up to 6W of output power, for a wide variety of industrial, medical, datacom, military and automotive applications.

The LT8301 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. The output voltage is set by a single resistor and the transformer turns ratio. Several off-the-shelf transformers, identified in the data sheet, can be used. The high level of integration, boundary mode and the use of low ripple BurstMode operation result in a simple to use, low component count highly efficient solution. Additional features included overload protection, a 380 µA no-load quiescent current with the output voltage in regulation, internal soft start, internal loop compensation, and output diode temperature compensation.

LT8301 is available in a TSOT-23 package. Extended and industrial versions operate over a junction temperature range of -40°C to 125°C. A high temperature automotive grade operates from -40°C to 150°C and a military grade operates from -55°C to 150°C. Pricing starts at $2.76 (1000).

Linear Technology; www.linear.com/product/LT8301