Simpler DC/DC designs with 15-W isolated monolithic flyback regulator

November 15, 2013 // By Graham Prophet
Linear Technology's LT8302 is a monolithic flyback regulator for of isolated DC/DC converter designs. 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 LT8302 operates over a 2.8V to 42V input voltage range, has a 3.6A/65V power switch and delivers up to 15W output.

The LT8302 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 enables the use of a smaller transformer compared to equivalent continuous conduction-mode designs. The output voltage is 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 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, a 380 µA no-load quiescent current with the output voltage in regulation, internal soft start and compensation, along with output diode temperature compensation.

The LT8302 is available in a small thermally enhanced SO-8 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 $3.47 (1000).

Linear Technology; www.linear.com/product/LT8302