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I am looking for a solution to step-down the 12V 82A from a server power supply to charge a 3S2P supercapacitor to 8.1V. Not sure which buck converter to go or if there are any specific limitation to them. Would a LTC3824. Based on the datsheet I calculated 198nH at 90A but can't seem to find a suitable inductor. Where am going wrong?

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    \$\begingroup\$ You will run into problems above 20 A, which is usually where multiphase buck converters come into the picture to go around that. Try LTC7871 or parallel multiple ~20 A buck converters. The lack of off the shelf inductors available reflects that. \$\endgroup\$ – winny Aug 3 at 8:06
  • \$\begingroup\$ Thanks. The LTC7871 is a bit beyond my expertise i'd rather do couple in parallel, How did you determine the current limit ? \$\endgroup\$ – George Aug 3 at 8:33
  • \$\begingroup\$ Several ways. Empirical testing and search. The number of commerically available inductors available drops significantly after 20 A, as well as integrated regulators available, or they become multiphase. Look at motherboards VRMs too, they are usually around 15-25 A per phase. \$\endgroup\$ – winny Aug 3 at 8:47
  • \$\begingroup\$ Forgot to mention the voltage of the supercapacitors, i've edited my question to show 8.1V. These VRMs or Desktop power supplies can't supply enormous current. Hence i chose to go with server power supplies. \$\endgroup\$ – George Aug 3 at 8:56
  • \$\begingroup\$ What about voltage divider if you are not charging it regularly. Which supercapacitor are you using btw? \$\endgroup\$ – JaySabir Aug 3 at 9:16

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