CoolMOS offline flyback — what the 650 V rating means for the BOM
The ICE3B0365JG is an Infineon CoolMOS series integrated offline switcher using a flyback topology, with the power MOSFET and controller in one PG-DSO-12 package. The 650 V breakdown voltage on the internal switch gives the headroom needed for universal-input AC-DC designs — a 400 VDC bus with reflected voltage spikes stays well inside the safe operating area. Switching at 67 kHz with a 75% maximum duty cycle, this part suits isolated flyback converters where the transformer size is a design constraint — the frequency keeps the magnetics compact while the duty cycle allows a wide input range without pulse-skipping.
Supply range and fault protection — what the controller handles
The Vcc supply range of 10.3 V to 26 V covers the typical bias winding output of a flyback converter; the undervoltage lockout thresholds are set inside this window so the controller starts cleanly and stays running through line dips. On-chip fault protection includes current limiting, open-loop detection, overload, over-temperature, and over-voltage shutdown — the device latches off or auto-restarts depending on the fault type, eliminating the need for a separate supervisor IC in most designs. The soft-start control feature ramps the duty cycle gradually at power-up, limiting inrush current into the output capacitor and preventing transformer saturation during the first few switching cycles.
PG-DSO-12 package — thermal and board-fit
Housed in a 12-BSOP with exposed pad (PG-DSO-12), the package is designed for surface-mount assembly. The exposed pad on the bottom of the 7.50 mm-wide body must be soldered to a copper area on the PCB — the thermal resistance to the board is the primary path for dissipating the heat from the internal MOSFET. Operating junction temperature spans -25°C to 130°C, which covers industrial ambient conditions up to about 85°C with the self-heating margin typical of a flyback converter running at this power level.