15W, high-voltage flyback regulator does it without opto-isolator

February 07, 2017 // By Christoph Hammerschmidt
With an output power of 15W and a wide input voltage range from 18V to 560V, Linear Technology’s LT8315 high voltage monolithic flyback regulator is targeting electric vehicles and battery stacks as well as general automotive, industrial and medical applications. By sampling the reflected isolated output voltage across the third winding on the power transformer, the part requires no opto-isolator or LT1431 for regulation, this simplifying the design of isolated DC/DC converters.

The LT8315 operates in quasi-resonant boundary mode, which is a variable frequency current mode control switching scheme, resulting in better than ±1% load and line regulation. 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, a 0.30A/630V integrated power switch, undervoltage lockout with hysteresis, along with output diode temperature compensation.

The LT8315 is available in a TSSOP-20 package with four pins removed for high voltage spacing. 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. www.linear.com/product/LT8315.