These ICs integrate a flyback controller and power switch in a single package, aimed at low-power chargers and adapters. Integrating the switch simplifies power-supply design — there's no separate step to select, match and lay out an external switch, shortening the prototyping cycle, which helps in BOM- and board-space-constrained products. The trade-off is that voltage and current headroom are fixed by the integrated switch, leaving less power headroom than an external-switch design.
Reading the Key Parameters
- Series/type: Catalog parts fall into a primary-side feedback architecture (no optocoupler loop), a general-purpose type with an integrated 650V MOSFET, and a high-frequency type with an integrated 650V GaN FET. GaN parts reach higher frequencies with lower on-resistance; MOSFET parts cluster at lower frequencies.
- Integrated switch and on-resistance (int_mos / rdson_ohm): In the MOSFET and GaN series, the integrated switch is rated 650V, with on-resistance spanning 0.15~6Ω. Lower values mean lower conduction loss and higher supportable power, but usually come in larger packages (e.g. DFN6x8) — weigh conduction loss against board footprint.
- Maximum switching frequency (fsw_max_khz): Catalog parts span 65~200kHz; the 200kHz tier currently appears only on GaN parts. Higher frequency allows smaller magnetics.
- Package: Ranges from SOP-7L/8L and ESOP-7L/8L to DFN5x6/6x8/8x8. The DFN family has lower thermal resistance, suiting high power-density designs.
Three Steps to Select
- Fix the integrated switch type (MOSFET/GaN) and voltage rating by target power and efficiency goals.
- Evaluate full-load temperature-rise margin using on-resistance and package thermal resistance together.
- Match transformer design and EMI budget to switching frequency and control mode.
Common Pitfalls
- Comparing on-resistance alone while ignoring package thermal differences — the same Rdson can run hotter in a smaller package.
- Assuming an integrated solution is always cheaper, while ignoring the hard power ceiling set by the switch's voltage/current rating.
- Substituting a high-frequency GaN part for a MOSFET part without re-checking drive loss and EMI margin.
To cross-compare parts by on-resistance, switching frequency, package and other parameters, use our online selection tool, or contact us for part-selection support.