PSR flyback converter with integrated power MOSFET

The Texas Instruments LM25180 is a PSR flyback converter with high efficiency over an extended input voltage range of 4.5V to 42V. The isolated output voltage is sampled from the primary-side flyback voltage, removing the necessity for an optocoupler, voltage reference, or third winding from the transformer for output voltage regulation. The high level of integration produces a simple, reliable and high-density design with just one component crossing the isolation barrier. BCM switching allows a compact magnetic solution and better than ±1.5% load and line regulation performance. An integrated 65V power MOSFET produces output power up to 7W with enhanced headroom for line transients.

The converter simplifies the implementation of isolated DC-DC supplies with optional items to optimise performance for the target end equipment. The output voltage is fixed by one resistor, while an optional resistor increases output voltage accuracy by negating the thermal coefficient of the flyback diode voltage drop. Further features comprise an internally-fixed or externally-programmable soft start, optional bias supply connection for higher efficiency; precision enable input with hysteresis for adjustable line UVLO, hiccup-mode overload protection, and thermal shutdown protection with automatic recovery.

The flyback converter is available in an 8-pin, 4mm x 4mm, thermally-enhanced WSON package with 0.8mm pin pitch.