88 W flyback with 650 V CoolMOS — the power supply workhorse
The Infineon ICE2QR0665XKLA1 is an offline flyback switching controller with an integrated 650 V CoolMOS power MOSFET, part of the CoolSET™-Q1 family. It delivers up to 88 W in a flyback topology, switching at 52 kHz with a 50% maximum duty cycle. The internal switch handles the power stage, so the external BOM stays lean — just the transformer, optocoupler feedback, and a handful of passives. Fault protection covers current limiting, overload, overtemperature, and overvoltage, which simplifies compliance testing for isolated supplies.
52 kHz switching — transformer sizing and EMI
At 52 kHz the switching frequency sits in the sweet spot for ferrite core transformers in the 50–100 W range — small enough to keep the magnetics compact, low enough to avoid the EMI headaches of 100 kHz+ designs. The 50% duty cycle limit sets the maximum on-time for a given input voltage, so the transformer turns ratio needs to be calculated for the lowest bulk capacitor voltage at full load. The 650 V breakdown gives 200 V+ of derating headroom above a 400 V DC bus, which covers line surge and leakage inductance spikes without an external snubber eating efficiency.
PG-DIP-8 through hole — rework and storage
The PG-DIP-8 package (0.300" body, 7.62 mm pitch) is through-hole only, which means hand-solder friendly for prototypes and rework, but no wave-solder paste-in-hole process without a manual step. No moisture sensitivity level to track — DIP packages are generally MSL 1, so no bake required even if the tube has been open for months. Store the tubes in a dry cabinet below 30°C to keep the leads oxidation-free; the ROHS3 compliance means the solder finish is matte tin or NiPdAu, not SnPb.