i'm designing a varable-frequency drive with 2 H-bridges based on IR2108 half-bridge drivers. I want it to drive a 220v single-phase motor. Reading the datasheet i got a little confused on choosing the right bootstrap diode (see the datasheet, this is the only diode on Typical connection chart): a lot of people on various forums wrote that they used Schottky diodes for their design. As the wiki says, the maximum reverse voltage of Schottky diodes is less than 200 V. So, assuming that the working voltage of my circuit will be notably higher, should i just use regular diode with appropriate voltage? What problems may come up with this solution?


1 Answer 1


Yes, you definitely need a diode that can withstand the full driver output voltage. The cathode will be boosted to Vcc above that voltage while the anode is held at Vcc.

The lower leakage of a non-Schottky diode will be an advantage, but the slower speed may affect the efficiency of the boost function. However, that part of the circuit usually has plenty of design margin, so it shouldn't be a big deal.


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