900 V CoolMOS in a fully isolated package
What the 900 V rating and 5.7 A current mean for your design
The 900 V Vdss rating places this part squarely in high-voltage offline applications — flyback converters, PFC boost stages, auxiliary power supplies for industrial drives, and two-switch forward topologies where the DC bus sits at 400 V to 800 V. The 5.7 A continuous current at 25°C is derated to about 3.6 A at 100°C case temperature; the 32 W dissipation limit at Tc=25°C sets the practical thermal ceiling. Gate charge of 34 nC at 10 V is moderate, so the gate driver doesn't need to be oversized.
Infineon lists the IPA90R1K0C3XKSA1 as Obsolete. The date-code and lot traceability on any offered stock should be verified, as gray-market material for an obsolete CoolMOS part is a common counterfeit risk.
Package and temperature grade — installation context
The PG-TO220-FP (Full Pack) is a through-hole package with a fully molded back — no exposed metal tab. This simplifies assembly: you bolt it directly to the heatsink without a sil-pad or mica washer, though thermal compound is still recommended. The input capacitance of 850 pF at 100 V Vds is modest, so switching losses at frequencies up to 100 kHz are reasonable for a 900 V device.