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Technology Stocks : Wolf speed -- Ignore unavailable to you. Want to Upgrade?

To: EvanG who wrote (10542)	8/29/2022 12:00:35 PM
From: slacker711	Read Replies (1) \| Respond to of 10712

Compiled the on resistance for automotive qualified 1200V SiC mosfets from various vendors. Is there some sort of advantage to some of them having larger values? My understanding is that the Rds(on) is inversely related to the breakdown voltage. It is possible that Wolfspeed's 1200v MOSFETs have a higher margin of safety than the others but the discrepancy is too large for that to be a good answer. Looking around, Wolfspeed is selling automotive qualified bare die MOSFETs that have a Rds(on) of 17mohms at 1200v. wolfspeed.com I can't believe that packaging is adding that much resistance but I don't have an explanation on the enormous difference between packaged and die specs.

To: EvanG who wrote (10542)	8/29/2022 1:44:53 PM
From: Lou Weed	2 Recommendations Recommended By EvanG slacker711 Respond to of 10712

The lower the Rdson, the larger the die, the better the thermal resistance, the higher the current rating and most importantly - the higher the cost. One of the big advantages of SiC is the much lower increase in Rdson over temp (25C to 175C) compared with Silicon devices. You can see that II-VI has the best performance over temp with respect to Rdson. An equivalent silicon MOSFET would see the Rdson increase 2.5x to 3x over the same range. Any die <10mOhm will typically be used in power modules as they dissipate too much power for standard discrete packages. Automotive customers are looking for the lowest possible Rdson ratings for their traction inverters. Traction inverters run at relatively low switching frequencies (~10kHz) due to motor limitations and higher power levels (100kW+). As a result, the higher capacitances of the larger die aren't a prohibiting factor - it's all about lower Rdson for the inverter section. Now the on-board-chargers (OBC) switch at much higher frequencies (>100kHz) and run at lower power levels (up to 22kW). For these circuits, capacitance is the important parameter, not Rdson. At higher switching frequencies you want smaller die with smaller capacitance (higher Rdson). Hope this helps.....