No-opto flyback regulator delivers up to 15W

The LT8315 from Linear Technology is a high voltage monolithic flyback regulator that is said to simplify the design of an isolated DC/DC converter. 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.

The LT8315 operates over an 18V to 560V input voltage range, has a 0.30A/630V integrated power switch and delivers up to 15W of output power. It is therefore suitable for electric vehicles and battery stacks, as well as off line, automotive, industrial and medical applications.

Several off-the-shelf transformers can be used for numerous applications. 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 are said to 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, accurate enable and under voltage 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 junction temperatures ranging from -40 to 125°C. An automotive grade operates from -40 to 150°C.

Peggy Lee