This document describes a simplified design of an isolated power supply. By examining the primary-side flyback pulse waveform, this product does not require opto-isolators or extra transformer windings to maintain regulation, and the output voltage can be easily programmed with two resistors.
The document introduces the LT3748 as a switching regulator controller specifically designed for flyback topology applications. It eliminates the need for third windings or opto-isolators by inferring the isolated output voltage directly from the primary-side flyback waveform.
Key features include boundary mode control (critical conduction mode) which improves load regulation, an internal gate driver capable of 1.9A average current, and a low-dropout regulator for the INTVcc pin. The device supports high-temperature operation in various grades and includes over-current protection.
No, the LT3748 does not require an opto-isolator or extra transformer winding to maintain regulation.
The built-in gate driver has a capability of 1.9A average output current for both rising and falling edges.
The internal threshold detects when current exceeds the programmed range if the voltage at the SENSE pin exceeds approximately 130mV.