One challenge in MOSFET design is the “silicon limit.” Every doubling of voltage-blocking capability leads to a five-fold increase in RDS(on). Yet Infineon beats the silicon limit with the 900-V members of its CoolMOS family.
These devices exhibit 120-mΩ on-state resistances in TO-247 packaging, 340 mΩ in TO-220s, and 1.2 Ω in D-PAKs. That’s about 75% better than conventional 900-V MOSFETs. Looking at the figure of merit (on-state resistance times gate charge), they also boast values down to 34 Ω-nanocoulomb.
In practice, a designer could use one of the 900-V chips in a flyback power supply for an LCD TV in lieu of a pair of 600-V MOSFETs, saving energy as well as bill-of-materials cost. The 900-V rating also allows series-connection of photovoltaic panels, reducing cabling power losses and costs.
Samples are available now. The volume price for 120-mΩ devices in TO-247 packaging will be below $3.50 each.